Auto Audio: Choosing, Installing, and Maintaining Car Stereo Systems 0070765367, 9780070765368

Citation preview

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CAR STEREO SYSTEMS %. Sit OOL

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Assembly Installation

Maintenance Repair

Andrew Y

OPAMP TECHNICAL BOOKS 1033 North Sycamore Avenue Los Angeles, CA 90038 464-4322 -(800) 468-4322 Monday-Saturday 8:00-5:30

Tel. (213)

Auto Audio

Other books by Andrew Yoder Pirate Radio Stations: Tuning into

Build Your

Own

Underground Broadcasts

Shortwave Antennas

—2nd Edition —4th Edition

The Complete Shortwave Listener's Handbook (also with

Hank Bennett and David

T. Hardy)

About the cover The audio system on

the front cover

was

installed in a

1993 Mazda Miata

convertible

by Jim Kessler and Jeff Fleming of East Coast Auto Sound from Rockville, Maryland.

The system components >-

> » *-

> > > > >-

are as follows:

Eclipse

ECD-510 AM/FM/CD player/changer

Eclipse

ESD-530 12

Eclipse

EQS-2000

Eclipse

EQR-2140 DSP

disc

digital

sound processor (DSP)

controller

Precision

Power A404 4 x 50-W

Precision

Power A600

1

controller

changer

x

amplifier

600-W

amplifier

Canton RS5 3-way component speaker system Canton RS2 2-way component speaker system

JL Audio

four 10" dual voice coil subwoofers

> > >

Audio Authority Optima battery

>•

VSE Quantum

Soundquest cables and wires

Phoenix Gold 160-A alternator

The custom

Pro security system

sound system include a motorized tambor door to cover the compartment to conceal the compact disc changer and the DSP, custom handmade front-door speaker enclosures and rear-deck speaker enclosures, a custom center console to house a Motorola cellular telephone, and a dual features in this

in-dash components, a motorized trunk

isobaric speaker enclosure for the subwoofers.

Auto Audio Andrew Yoder

McGraw-Hill, New York

Inc.

Washington.! Milan bsbon London Madrid M Caracas Montreal New Delhi San Juan Singapore Sydney Tokyo Toronto San Francisco

©1995

by McGraw-Hill, Inc.

Published by McGraw-Hill,

Inc.

Printed in the United States of America. All rights reserved.

no

responsibility for the use of

The

publisher takes

any materials or methods described

in this

book,

nor for the products thereof.

pbk

3456 7 89

10 11

he

2345678

9 10

Product or brand names used that there

with an

may be

initial

DOC/DOC DOC/DOC

in this

9 9 8 7 6 5 9 9 8 7 6 5

book may be

proprietary claims to such trade

capital or

it

of the capitalization used,

has been capitalized all

names or trademarks. Where we believe names or trademarks, the name has been used

trade

used by the

in the style

such names have been used

in

an

name

editorial

claimant. Regardless

manner without any

intent

convey endorsement of or other affiliation with the name claimant. Neither the author nor the publisher intends to express any judgment as to the validity or legal status of any such proprietary to

claims.

Library of Congress Cataloging-in-Publication Data Yoder, Andrew R.

Auto audio / by Andrew Yoder. cm. p. Includes bibliographical references

ISBN 0-07-076535-9 1.

Automobiles

TK6570.A8Y63 629.277—dc20

(H)

(p.

329) and index.

ISBN 0-07-076536-7

— Radio equipment.

I.

(P)

Title.

1994 94-38855 CIP

Acquisitions editor: April D. Nolan Editorial team:

Robert E. Ostrander. Executive Editor Norval G. Kennedy,

Book

Editor

Production team: Katherine G. Brown, Director

Jana L Fisher, Desktop Operator

Nancy K. Mickley, Proofreading Toya Warner, Computer Artist Jodi L. Tyler, Indexer

Design: Jaclyn

J.

Boone

WK2 076536-7

Contents Acknowledgments

The

potential for hearing loss

Introduction 1

ix

How

xi

xiii

and where

choose your audio system

to

Buying new equipment

2

Buying used equipment

1

18

Evaluating your needs

Simplified equipment selection listing

Conclusion

2

Head

26

35

units, equalizers, signal processors,

36

and changers Head units 37

Digital signal processors

Equalizers

Conclusion

3 Amplifiers

71

72 74

75 77

Principles of amplification

Various amplifier ratings and specifications

94

Amplifier design configurations Additional amplifier features Practical amplifier tips

Conclusion

116

and

101

tricks

1

08

88

1

4 Speakers 117 Some simplified sound The sound

117

basics

120

stage

Speaker action and components Speaker

1 30

137

Buying speakers

Other speaker specifications

Nominal power handling

Peak power handling Speaker

121

classifications (by frequency)

1

1

43

145 45

145

polarity

Impedance and interconnecting speakers Conclusion

1

146

53

5 Speaker enclosures 155 Enclosure materials 1 56 Speaker enclosure shapes 159 Speaker enclosure damping 1 62 Speaker enclosure designs and techniques Building speaker enclosures

6

Filters

1

and crossovers

186

Building and buying crossovers

Basic crossover theory

1

188

89

Determining the crossover values

197

Crossovers for three-way speaker systems

Conclusion

L pads

209

few antenna basics

Locations

Motor noise

209

21

212

Vehicle antennas

213

Simple antennas for Conclusion

203

206

208

7 Antenna systems

A

64

187

Crossover uses

Resistance and

1

78

218

AM and shortwave hobbyists

213

8 Wire, cabling, connectors, and transmission systems 219 Should

I

Wire

221

FM

purchase high-end audio cables?

transmitters for

compact

disc players

226

228

Making connections

Planning and assembling the system

the car

in

244

249

Shortwave broadcasting

Auto audio shortwave equipment Shortwave information

232

236

Power cables and fuses Grounds 238 Conclusion 241

9 Shortwave radio Propagation 246

220

252

254

10 Installation techniques and real-life stories 1981 VW Rabbit 259 1975 Ford Granada 268 1986 Chevrolet Celebrity 273 1990 Geo Tracker 280

284

Conclusion 11

Repairing car audio systems 287 Tracking down the problem 289 Organizing your work Safety procedures

Repairing speakers Equalizers

Head

units

298 299

Dedicated amplifiers

Conclusion

Sources Glossary

289 293

310

324

309

308

285

258

Bibliography

Index

329

334

About the author

341

Acknowledgments Because of the scope of this book, it could not have been written without help from many people and organizations. Thanks to Aaron Bittner and John Baker for allowing their vehicles to be audio guinea pigs. Thanks also to John Baker, Aaron Bittner. and David McCandless for the work on the magazine ad and to George Zeller for his personal views on the performance of the Philips

DC-Ill.

Thanks to (in no particular order or grouping): Anne-Marie de Walle and Mark Noordanus of Philips, Stan Harrison of Harrison Labs, David A. Berkus of Sanyo Fisher USA. Roger Alves and Scott Erickson of Scosche, H. Christopher Parvin of Rockford Fosgate, Mike Giffin and Mike Silber of Infinity. Jeannie Kane and Julie Knapp of Car Audio & Electronics. Alasdair Patrick of Audioquest, Don Zamora of Altec Lansing.

Hoffmann of Linear Power, Sam Fontaine of AudioControl, Sarah Parker of Allsop. Audiophile, everyone at Parts Express, Thomas Brannam of Authorized Parts, Robert Palmer of Monolithic. Jennifer Frantz of Morel Acoustics USA and Meir Mordechai of Morel UK. Sid Dutcher of

Also. Valaine

W

Collins

USA.

Keith Carter of Bostwick.

Vern Donkers of Pioneer Electronics USA, Steve Outhier of Shane Harden and Kenneth Persson of Clif Designs, Muriel Neddermeyer of MTX. Ken D Amato of Audison USA, Jim Toplian of Alpine, Matthew Keown of JVC Company of America, John-Paul Lizars of Nakamichi America. Ian Castell of HiFonics. Lawrence Hit< h of Madisound. Ralph Nichols of Polydax. A. V Mannino of M & M Electronics, Allen Baron of Polk. James Stevens of Additionally.

Stillwater Designs, Al Milbert of Milbert Amplifiers.

i\

cknowledg merits

Blaupunkt, Mike Gatto of Denon, Michele

Windsor

of Eclipse,

and

Pam

Neil

Houde

of StreetWires,

Ray

and Elizabeth Anderson of Jensen.

book a chance, for allowing borrow her computer when mine blew in the final stretch, and for being a great encouragement through the writing and publishing process. Thanks also to Mark Rumreich. Norval Kennedy, and Bob Ostrander for the thorough editorial work. Thanks to Toya Warner and Brian Allison for the excellent artwork, to Jan Fisher for the nice layout, and to Nancy Mickley for catching inconsistencies while proofreading. Thanks also to Jackie Boone for working up the fun design for this book. Special thanks to April D. Nolan for giving the

me

to

Very special thanks to Yvonne for improving always pushing me to do better.

my

writing quality

and

for

x • • • v • •

The

potential for hearing loss

WARNING!

The sound equipment described

causing permanent It

damage

has been proven that

if

to

in this

book

is

capable of

your hearing.

someone

is

subjected to

90 dBA

(decibels average)

sound for 8 hours per day, he or she will eventually experience a permanent hearing loss of varying intensity. Some sound systems have even reached 150 dBA. Imagine the potential for hearing damage!

of

The

car stereo sound-off competitions, magazines, and manufacturers often

high-volume systems; in fact, the sound-off competitions revolve around volume, clarity, and quality of the installation. The manufacturers can glorify

sell

many more

of their products

if

buyers intend to use higher power, so

manufacturers obviously push for higher power and attempt to glorify

it.

is common, and it has been on the increase and manufacturing jobs, rock concerts, and high-powered stereo systems are to blame for most of these problems, which

The

fact

in the

are

is

past

that hearing

30

damage

years. Industrial

compounded by

the fact that

human

hearing degrades extensively with

age. Natural hearing loss does discriminate by sex; by the age of 65, the

average

woman will lose from 7 dB of hearing at 500 Hz to 15 dB at 4 kHz; man will lose from 7 dB of hearing at 500 Hz to 37 dB at 4 kHz

the average (Fig. 1-1).

natural decline in hearing begins its steady downward slope from age 30 onward. When this decline is assisted by loud music, the hearing loss can easily be accelerated tQ the point where you could be hard of hearing by the time you are in your thirties or forties (assuming, of course, that you are

The

xi

M

The

potential for hearing loss

presently in your teens or twenties).

you could be

By

the time you reach retirement age,

totally deaf.

you think that this section is intended to scare you, you're right. Hearing is tragic, and it's permanent. If you are so serious about audio that you can spend hundreds of dollars on an audio system for your car, then you should certainly be serious enough to take care of your ears so that you can continue to enjoy the hot sounds on the wide-open road. If

loss

Figure 1-1

CD

10

40

50

Age-years

s£2

5

^*

10

Women

en

C 'C

B

15

10 cu

X

20 25

1_

i

i i

20

30

1

1

1

1

i

40

50

60

70

Age-years

Age-related hearing loss for

men

(A)

and for women

(B).

Introduction For years, music has inspired and driven me to do more, faster and more passionately. To me, music isn't just something to end silence: it's blood coursing through my veins or a breath of fresh air rushing into my lungs.

Music

background Muzak;

isn't just

Ultimately, this

down,

it's

Wes

heroes

book

isn't

about music

in

it's

the soundtrack to

about auto audio;

your

car.

it's

my

life.

about music. To narrow

it

Unfortunately, you just can't have guitar

Harris and Paully Sanders dueling in your car anytime you want

to take a drive, so

you must

find a

way

to reproduce their sounds.

That

requires a sound system built specifically to tolerate the harsh environment of the car

These

and

to operate

factors alone

make

from the car's 12-V for

many

electrical system.

different possibilities; however, auto

audio has been quickly evolving over the past few years, so what

more advanced

is

available

equipment from the mid-80s. Also, all cars vary in style, complexity, and acoustics. In some cases, an installation might be simple in one particular car, but that same installation might require many days worth of work to install in another car. In other cases, an installation might sound great in one car, but it might not sound so good in another. Availability of equipment, car stereo dealerships, and buying information are other potential problems. And, last of all, the money that you plan to unload on a car stereo system is one of the key factors behind the components in the system that you finally purchase. today

As

it

is

is,

auto audio

is

(by light-years) than

a very

complex

subject

purpose, to have good-sounding music

in

—

your

all

one simple Because of the

to achieve

car.

Introduction

complexity of the audio issues,

many people seem

(good-sounding music) because they get caught up

One

of the largest sidetracks to auto audio

is

to forget the in

bottom

line

various side tracks.

competitions. All across the

country, people participate in sound-offs. At these events, car audio

systems are judged on level),

how

loud the system can go

(e.g.,

the sound pressure

the imaging, the layout of the installation, the looks of the

installation, tricky designs (such as hiding amplifiers

under fake floors and

motorized head unit doors), and the like. These events are interesting and they have greatly advanced the technology of auto audio; however, these competitions sometimes cause condescending attitudes toward people with "lesser" systems.

Because these systems are based,

in part,

on cosmetics, cosmetics play a

large role in the overall system. In fact, the cosmetics of the system are

sometimes emphasized to the point where the audio system is installed in it and the car are difficult to find any practical use for. Some competition cars aren't even street legal. Others, such as one trophy winner that has gold-plated amplifiers and speakers, is so absurdly overdone that you could never drive it in public without one or more bodyguards. such a way that both

The quest of this book is simply to help you put good-sounding music in your car: no hype, no egos, no glitter. have tried to include methods of obtaining I

many of us don't have the money to buy a high-end system for the car, but it is often possible to find a fair- or good-sounding system that will fit your budget. a system as cheaply as possible because

In

keeping with

this goal,

I

talked with

some manufacturers and

mail-order

As a result, a few money-saving coupons are included in the back to help you get a start on your system. Depending on your system choices, the coupon discounts will more than pay for the price of this book.

distributors.

Affordable information can be hard to find, but not in this case.

Another difference in this book is that have directed it toward the novice with no car audio or electrical experience. am not an engineer or a mechanic. Instead of glossing over some of the problems that had with installing systems, have described them so that you can better understand what you will be encountering and some of the routes that you can take to overcome difficulties. I

I

I

I

have spent a considerable amount of time writing this book and making the information contained within as useful as possible. I certainly hope that you I

will find

that

it

is

useful as well.

troducti

don't do equipment recommendations and don't have the resources to respond to all of the questions about system designs and installations (read and write to Car Audio & Electronics. AUTOtronics, Auto Sound & Security, and Car Stereo Review, instead); however, if you would like to drop me a line concerning this book or your personal experiences with auto audio, feel free to contact me: I

I

Andrew Yoder P.O. Box 109 Blue Ridge Summit,

PA 17214

1

How and where to choose your audio system Possibly the toughest aspect of

owning a custom car audio system

is

just

searching through piles of magazines, catalogs, and sale flyers to pick out the components that you want. There's a mind-boggling array of car stereo equipment on the market, and it can be rather difficult to research all of it After awhile, you might be ready to pull out your hair and continue listening to the only station that you can receive on the AM radio in your '75 Dodge.

Of course you don't

like

the format of banjo opera music that

there, but you're stuck, right?

If

is

featured

on

the banjos start to catch up with you, you

down and ask the local car stereo installation center to "pick something that sounds good for XXXXX amount of dollars." Taking th.it route will most likely pull in a good system, but one that's not worth the vou stack of bills that you will have to pull from your wallet C>' might break

1

How

and where

to

choose your audio system

might read through the car stereo magazines and find a few highly rated components. Once again, this is a great way to pay for much more than you are getting.

The next option

to get nervous about all of the prices that you have seen magazines and from the local installation shop and settle on something that is inexpensive from a discount department store. This route is somewhat different from the other two because you will get exactly what you pay for. Taking the third route will probably land you a cheaply manufactured system that sounds bad. is

in the car stereo

The

last

option

is

to search through stereo

magazines and check out the little work and luck, you will

prices from the mail-order companies. With a

wind up with a good system

at a

low price.

Buying new equipment Just about everywhere

equipment.

In a

you

look,

system for a great price can be

Buying from a By

taking the

people

who

someone

is

selling

new

car stereo

world inundated with auto audio equipment, getting a great

first

route,

difficult.

local installer

you

will

most

likely

wind up with a

operate these businesses are professionals

many systems and who have had

solid system.

who have

The

installed

plenty of experience installing various

pieces of equipment throughout different locations of a car's interior.

They

have seen which amplifiers run into problems with clipping and distortion and which pieces are returned to the shop for repair. One problem is that the installers have ultimate authority when suggesting new equipment to the novice car-stereo-owner-to-be; thus, the novice might have no idea what any given piece of equipment typically sells for, and perhaps even be charged for

more than

the suggested retail price.

Another problem

is

competition. Most people just pick out the closest car

stereo shop, select the equipment, and get everything installed. find

all

that

many

You won't

advertisements for these shops. As a result of the lack of

competition, you won't find gas-station-style price wars with car stereo

equipment from the

installation shops.

Wa Buying new equipment

The

problem with blindly picking all of your equipment from a local sheer numbers. Chances are that the car stereo shop of your choice is a rather small business that sells equipment and installs it for people in the community. The bottom line is that it probably sells a relatively small amount of car stereo equipment. Although the previous paragraphs hint at the possibility that your local car stereo shop might be intentionally turning your ignorance into large profits, there's another condition to consider. last

installer

is

Dealers must purchase specific quantities of equipment to

customers.

If

sell

to their

they don't have the clientele to reach a certain quota of sales,

they can't afford to buy a larger quantity of a certain product. Buying

in

means that the manufacturer won't give the shop as good As a result, the price at the local shop might appear to be

smaller quantity price per unit.

high. but. in reality, might be as

cheap as

it

can possibly

sell

a

the

merchandise. This information

is

not necessarily intended to keep you from purchasing

products from the local car stereo shops. Buying locally is a good way to support the people in your community and also to support quality car audio in

your hometown. Supporting the

local

shops could mean helping your

friends, helping the local

economy, and possibly enabling the shops

sponsor car audio events

in

On

to

your area.

the other hand, you probably

will

not find a low price at the small, local

do you want to spend and whom do you want to have your money? If you would rather spend a few extra dollars to help out your local shop, then by all means do it. You can bet that a long-distance mailorder shop or a chain store probably won't ever help out in your community. shops.

How much money

(J Following

the magazines

The mobile audio magazines on

the market are excellent sources of

information for purchasing a system for your car (Fig. 1-1). You can find information and specifications on most of the pieces of equipment that are

on the market. Both Audio and Car Audio and Electronics feature massive guides to car stereo prices and specifications in one of the spring issues. These listings are excellent if you are planning to become an active

currently

car-audio consumer. Aside from the

listings,

these magazines also feature

plenty of product reviews, new-equipment glimpses, glossy manufacturer

advertisements, and helpful

tips.

'^^.Mjr^Vi

How

Figure

1

and where

to

'

^T MF^F ^W ^J

choose your audio system

-1

SounasOreai.

The various auto audio magazines that are currently available in North America.

On

the downside of following the magazines

nature. At this writing,

none

feature distributor advertisements.

what

is

a

good

price for

is

their inherent

commercial

of the popular newsstand car audio magazines

As a

result,

it

is

very

any given component. (Nearly

difficult to all

determine

of the magazines

that pertain to other hobbies are loaded with "Crazy Bob's Discount

advertisements; for

some

reason, the car stereo hobby

is

House"

devoid of these ads

and it certainly hurts the hobbyists!) The only prices that are listed in these magazines are the manufacturer's suggested list prices, which often are as much as several hundred dollars over the distributor's selling prices on the higher-end components. The average consumer is left in a haze, not knowing the average price for any given piece of equipment. Although the advice that is given by the various car stereo experts is very good, you also have to remember who pays the bills at the magazine office. The subscription or single-issue cost is only part of the cash flow received by these magazines. The major source of revenue is generated by all of those beautiful, full-color, full-page advertisements throughout the magazine. As a result, the magazines are quick to push the expensive components and maxi-systems, whether they are necessary or not. Instead of finding test reports and reviews of average components or good deals, you will find test reports and reviews of the very best that the industry has to offer or you will read about new, innovative technology that everyone else will be talking about in five years.

Buying new equipment

More disconcerting to me is the general bias of the magazines toward expensive cars and expensive, high-end audio. Very few of them highlight articles on installation how-to, troubleshooting, maintenance, or repair. You are

more

23

coats of paint, a

a bright and glossy photo review of a classic car with

likely to find

chromed engine, $10,000 worth of stereo equipment inside, and a bikini-clad girl draped across the hood. Maybe this is fine drooling material for some folks, but it won't show you how you can improve the sound system in your car.

The tone

some

some of the how-to hands-on approach, the emphasis is generally on picking out a system, then taking the magazine to an installer and saying "I want something like this." have even seen an article that flatout told the consumer never to install his or her own equipment or to buy used components. Both claims are bogus; if you are careful, patient, and understand your limitations, you can buy used equipment and successfully install at least some of your own setup. of

of the magazines

is

also reflected in

articles that appear. Instead of taking a

I

I

suppose that a sociologist could

in

consumer

electronic devices have first

impulse

relate the car stereo industry to the

ideals over the past several decades. In the

isn't to fix

become it.

disposable;

1980s and

change

'90s,

whenever something breaks, the it away and buy a new one. To

but rather to throw

most people today, if something breaks down once, it is considered to be "junky and unreliable." This is a shame because the high-quality car stereo equipment is built to last; otherwise it couldn't survive the heat, cold, and constant vibrations. At least some of this equipment could be repaired and put back into service without much trouble.

Car Audio and Electronics and AUTOtronics are my two personal favorites from the group because they take more of a hands-on approach to auto audio, and find them to be much more in touch with my needs. guess that would be happiest with a mimeographed newsletter that was filled with technical and installation tips and classified advertisements, but that's my bias. The strong points of Car Audio and Electronics are the annual buyer's guide and the excellent laboratory ratings/face-off component articles that are featured each month. The strong points of AUTOtronics are its fullI

I

I

coverage beginner developments plus "louder In

is

articles that explain its

many

of the basics

apparent stance against the "bigger

and new is

better"

and

better" rhetoric.

the long run, the car stereo magazines are excellent resources.

serious about setting

up a good system, then you must subscribe

If

you are

to several of

^ v -

When

>

Where

>-

Did you buy

>

Why

>-

Have you ever had any problems with

>

Do you smoke?

>•

Do you have

did you buy did

it?

you buy it

new

are you selling

it?

or used? it?

it?

the manuals and the manufacturer information?

Of course, not everyone will be honest with you, but some people will signs to beware of are physical damage and dirtiness. Physical perfection is not a must, but heavy wear can cause problems in some

be.

Two

11

How

and where

to

choose your audio system

equipment. For example, an amplifier can usually get stepped on and scratched, yet still work perfectly. But a worn cassette deck might have more problems; heads can wear out, fragile buttons can wear out or

become

and motors and gears can break down and strip. If the owner says that he or she doesn't smoke and that the unit was purchased new, but the front panel (in the case of a head unit or an equalizer) is yellowed from nicotine, then you know that the owner's answers are unreliable. intermittent as a result of dust, smoke, or grease,

you know the years of different equipment releases, you can figure out whether or not the owner is telling the truth about buying the unit new. Also, when checking the physical condition of the equipment, be sure to check the serial numbers or equipment part numbers. Beware of equipment that has the identification stickers ripped off. and do not buy any components that have the numbers scratched or etched out. This stuff is almost certainly stolen. Buying stolen equipment not only encourages thieves, but it could get you in trouble. If

The

way

whether or not a component works is to test it out will bother to sell an unworking system if it is still in the car because it is too easy to see if it works and how well. If the component that you are checking out is anything except a speaker, check to see if the power indicator (usually an LED) lights. Then make sure that the best

in a car

to find out

stereo system.

connected.

wires are

all

might

you

let

Few people

listen to

In the

case of speakers or amplifiers, the owner

the system, including the part that you want to buy.

Check to be sure that the particular amp or speaker system connected to the system that you're listening to. If

you're checking out a head unit, be sure to press

make

all

is

actually

of the buttons

and

sure that they work. Either a particular control system in the unit could

be knocked out or a button could be broken or intermittent. You won't know if you don't check them. Don't just let the owner press a few buttons and

"See? It works great. Are you going to buy it?" Hastiness and highpressure sales are a warning sign that the system doesn't work as well as should, that the price is too high, or that the owner is an impatient jerk. say,

Beware in any case because if the owner is a jerk, he or she won't be and won't help out if you run into any problems. After

all

of these negative signs to avoid

distrust the

owner, there

excellent sign

if

the

is

one very

owner has the

and

reliable

these potential reasons to

positive sign to

watch

for.

It is

an

original box, manuals, installation

information, and/or receipts. For one thing,

12

all

it

it

rules out the possibility that

Buying used equipment

was stolen. Also, the component is less likely to have been bought secondhand by the current owner. One of the most important positive signs about having all of this information is that if the owner was so careful with the information that pertained to the component, he or she was probably just as careful (maybe more so) with the component itself. the unit

you listen to the system (or if everything looks good with a component that has been pulled from a system), and the component sounds good in that system, and the price is in your range, get ready to pull out your wallet or checkbook. If not. or if you aren't sure, use that night to reevaluate your If

needs.

If

want the component after "sleeping on it," call the owner make sure it is still for sale, and buy it. In the worst case of component might sell overnight: in the worst case of buying

you

still

the next day. waiting, the

when

you're unsure, you might buy something that doesn't work properly or

didn't

have a great price or you

If

you are interested

in

really didn't

want.

buying a system from someone on a computer

is no way for you to know if the seller is telling he or she will take your money and disappear. Other bulletin board users might be on your side; they will often alert everyone if someone offering something for sale is known to have ripped off others.

beware. There

bulletin board,

the truth or

In

if

one case on

lines.

a system that

I

frequent, a rip-off occurred across country

The person who was ripped

off told the story a

few times

after not

being able to pursue the case across international borders. After a few

months, a person from the other country checked in to say that he had read the posting, tracked down the offender, and somehow coerced him to return the money, plus some interest for the year and a half that he had it. Now that's cooperation!

computer systems, but there are also bargains. The arrangement to work well is for the bulletin board users to be honest and self-policing. If you plan to purchase a piece of equipment via this method, it is best to buy from someone who has had a lengthy presence on the system and has sold good-quality items in the past. Also, it's best not to put your life savings on a whole system that you see advertised. Purchase only as much as you can afford to lose. If it works, you've got a great deal; if not, at least you won't have to sell your car to cover rent or a mortgage. There are only

way

still

Installation If

rip-offs via

for the

consumer

shops and mail-order companies

safety

is

a top concern, yet you are

still

interested in picking

up

used equipment at better-than-new prices, the best locations to scour are car

13

How

and where

to

choose your audio system

stereo installation shops. (These shops were also covered in the buying

new

equipment section of this chapter.) Although the installation shops are not always a prime outlet for purchasing new gear because of the often-pricey dollar amounts, they can be excellent sources of used equipment. The mailorder companies were touted as being the least expensive location for purchasing new equipment, if you know what you want. Both are lumped together in this section for used equipment for two reasons: company sales and warranty/money-back guarantees.

Of the ways to buy used car stereo equipment, the only two ways that you can buy serviced equipment are from installation shops or from mail-order stereo companies. The second-hand stores and pawn shops are also companies, but these are more of an "as-is, all-risk"' adventure.

The advantage of having a company sell you a used product is that it has more responsibility to its customers than an individual with some old equipment. Not only do the companies need to worry about spreading a bad reputation, but they also have to worry about being blacklisted by the Better all of that, many people who take up car stereo and repair take pride in their work, and they wouldn't want to knowingly sell equipment that didn't work.

Business Bureau. Besides installation

Considering the amount of equipment, variety of cars brought in, and expertise that are present in the typical installation shop, you should feel free to ask about used equipment. Talk to the sales representative or

(depending on the

size of the

shop) and find out

if

owner

the shop has any

show customers used equipment in operation. If so, and compare the different units. If not, maybe the will be able to suggest someone to you who has the

standard procedure to

you

will

be able to

listen

sales representative

same piece

of equipment in his or her car. Or, perhaps the sales rep can you some good advice on the type of sound provided by that particular component.

at

least give

The company aspect guarantees. After

enough

price to

of sales

all, it

make

fits

in

with the warranties and money-back

would be tough to

the average installation shop or

sell

any equipment

at a high

some consumer insurance. As mail-order company that sells used

a profit without

a result,

equipment has anywhere from a 1-week to a 30-day money-back guarantee. With this standard guarantee, you are usually able to return the stereo component for any reason and get all of your money back, less shipping costs

14

(if

applicable).

uying used equipment

The average warranty on used equipment will days. Generally, if the stereo component fails period, you can get your money back or have charge. These warranties are usually voided physically

damaged

connected

it

it.

or

if

last

anywhere from 30

to

90

within the time of the warranty

the unit repaired free of

you have opened the unit, damaged because you incorrectly

the unit was

if

to a voltage or audio signal.

For any warranty or money-back guarantee, make sure that you have a hardcopy of the signed agreement, and be sure to read the specific terms. Some companies will void warranty agreements for reasons that might seem trivial to you. If you void a warranty and can't get your money back, it's your fault.

On

the whole, buying used equipment from installation shops and mail-order

is a good move. Some shops don't like to bother with hiring a repairman, so you might have a few problems finding what you want, unless you live in a major city. Check in the yellow pages for installation shops in your area and be sure to call first to make sure that they sell used equipment.

companies

Look through the stereo magazines for advertisements from the mail-order companies. You shouldn't have any problems with buying used and repaired equipment from these companies.

Pawn shops and second-hand On

stores

equipment from installation shops or mail-order companies is scouring the pawn shops and secondhand stores. With pawn shops and secondhand stores, you don't need to shell out much money, but you are completely at risk; you trade the security of having a guaranteed unit for saving a few extra dollars. the

flip

side of buying

The secondhand

thrift''

stores are generally lousy places to look for car

find something in one out of every five stores you look through, but it will usually be an 8-track player from 1976 or something equally undesirable. Few people donate car stereo systems to the Salvation Army.

stereo equipment.

You might

that

Pawn

shops, on the other hand, are great stores to look through for used car

stereo equipment or any other interesting electronics devices.

though when

financial hardships strike, the

the items of high technology. Likewise,

need

it

first

If

you are taxing your budget

seems as

seems as though the people who

to quickly liquidate their possessions are those

technology.

It

things to be liquidated are

to

who

dabble

in

high

buy your upcoming car stereo

15

WF aWF A^P J^E

£BaWFJ&aWWaIB4^FA^m A^BA^r Amtr A^m A^FA^m A^JAWw A^W A^m A^JA^m A

How and where

to

choose your audio system

system, beware of this warning sign! Don't overburden your budget, or your

beloved system could find a temporary

home

in a

pawn shop!

from a pawn shop are that you won't get money-back guarantee on your equipment and you could easily run across stolen equipment. You are totally at risk in pawn shops, so be sure to check the physical condition of the piece that you are interested in. Check all of the buttons, switches, and knobs to make sure that they all seem to function. Also look for worn jacks, scratches, dents, oil or grease, burns, and melted areas. If one or more of these conditions exist, if the price is 10 percent or less than the brand-new price, and if you are good with repairing audio equipment, it is probably worth your time and money to buy the component; otherwise, avoid it! You will only lose money on it.

The two

big warnings about buying

a warranty or a

on buying from classified advertisements, avoid You can't be sure that anything is or isn't stolen, but if the component's serial number has been scratched or etched out, it has almost

As

stated in the section

stolen equipment.

certainly

number stolen

been

stolen.

sticker or tag

It is

also best to avoid a piece of

equipment

if

the serial

has been removed, painted over, or covered. Buying

equipment not only supports the thieves (who make having even a system in your car risky), but it is illegal.

fair-quality stereo

find any equipment that has been altered in this way, complain to the management, and if you have a chance, complain to the proper state or local government bureaus. have heard that some states have been working to organize and clean up the pawn shops within their boundaries and thus remove the stigma of pawn shops as being a clearinghouse for stolen goods. In these areas, you should have fewer problems with If

you

store

I

purchasing equipment. Unfortunately, Pennsylvania seems to be almost devoid of closest states.

One

friend of

shops

pawn

shops.

The

ones to my present location are about 45 minutes away, in different But if you live in a city, you should have no problem finding several.

mine

in his locale.

regularly scopes out the bargains in three different If

this

is

your situation, good

pawn

luck!

Hamfests, computerfests, flea markets, and

consumer electronics shows The

market sections at hamfests, computerfests, and consumer shows are the best places to go for absolute minimum prices, with the trade-off of absolute maximum risk. Unfortunately, most people know nothing about these shows and they are missing out on some great buys and flea

electronics

interesting technology.

16

Buying used equipment

About half of the time when mention that am going to a hamfest to someone, the response is a joke, such as "So. are you gonna eat a lot of pork? Ha ha." Yeah, real funny. A hamfest is an amateur radio gathering, where some large, open area (such as a county fairground) is filled with commercial amateur radio vendors and another section (usually a section of I

I

lot) is filled with a flea market. The flea market is filled with shortwave and amateur radio parts that range anywhere from brand-new to dating back to the turn of the century.

the parking

anyone with an interest or expertise in an amateur radio operator. Of course, that was before the spread of personal computers and other electronic gadgetry. In many cases, the computer hobby overlaps the amateur radio hobby; thus, most hamfests are also computerfests. Because of the overlap between computers and amateur and shortwave radio, you can also find other consumer electronics at these events. Some of the larger events are even advertised as "consumer electronics shows" and all sorts of electronic equipment is present, although the core is still amateur and shortwave radio and computers. The smaller hamfests usually have little more than just shortwave and amateur radio equipment; however, the larger events are really interesting. You have no idea what you might find!

Just a few decades ago. nearly electronics

was

also

Most of the fests that have been at recently have been either radio or computer dominated: however, one large fest that went to a few months ago had a fair amount of car stereo equipment in the flea market. One table had a load of overpriced head units (mostly cassette decks) in fair-to-good condition. Another table had about 20 boxes full of junk. I

I

bought an '80s-era Mazda cassette deck and a Jensen amplifier for $8 The dealer said that both worked, although doubted it. Either way, thought that for $8. it would be fun to play with this old equipment. The dealer even threw in a free brand-new (still in the unopened plastic/cardboard packaging) 10-amp noise suppressor that had a list price of $29.95. Not a bad deal, even if the amplifier and head unit are junk. I

total!

1

I

to these fests and shows is that people pull junk out from everywhere in the house, attic, and garage and sell it off. After you buy a unit and take it home, it's yours. There is no store or home address to take just an empty fairgrounds; hence, the low prices. it back to

The main disadvantage

—

But the equipment and the

sellers

was wrong with a

unit, to

vary widely.

I

have had everything from tell me anything th.it their equipment

who were not afraid to those who flat-out lied about

very honest and friendly sellers

17

and wh- Because

all

of the speakers are held within the

speaker (the midrange), the sound individual speakers

will

cone

of the largest

not be quite as clean as

were mounted apart from each

if

the

other.

Raw speakers Advantages >- The system can be sizes of

tailored to spread out the

sound with

different

speakers mounted throughout the vehicle.

>- You can choose each speaker separately

to

fit

within your tastes for

sound.

>- The sound

is

cleaner.

Disadvantages

>

The speakers purchased

are

>" Much more space

(J)

more expensive because each speaker must be

individually. is

required for installation.

Woofers and subwoofers Woofers and subwoofers are

available in different sizes,

and

in a large variety

of enclosures.

31

How

and where

Free-air woofers

to

choose your audio system

and subwoofers

Advantages >- The

free-air

woofers and subwoofers can be mounted

decks or

in rear

other areas without the need for sealed enclosures.

>- Less space

is

required for installation.

>* Less money and work are required

for installation.

Disadvantages >- The free-air woofers and subwoofers usually cost comparable standard woofers and subwoofers. >- These items or something quality stereo

5s

"

They

system

is

slightly

more than

similar will usually attract attention that a

in the car.

require a sealed enclosure for

optimum performance.

Standard-mount "raw" woofers and subwoofers Advantages >- Standard-mount "raw" woofers and subwoofers are the expensive type of woofers and subwoofers.

>- They can be mounted

in locations that require less

least-

space than

commercially enclosed woofers and subwoofers.

>- They can be mounted

in locations that are

more convenient

for the

owner.

Disadvantages >- They >•

If

require, by

far,

the most custom installation work.

the speakers are being professionally installed, the cost will be

much

higher.

5* They require plans for the

32

that

you follow

size(s) of

specific equations or

your particular speaker(s).

predesigned box

Simplified equipment selection listing

Enclosed woofers and subwoofers Advantages >- The enclosures have been engineered

to

match the speakers

perfectly.

>- They provide a very professional look

in a

>* They are easy to remove if your car if you need the extra car space.

parked

is

durable box or tube. in

an unsafe location or

Disadvantages >* Enclosed woofers and subwoofers are much more expensive (per speaker) than just buying "raw" speakers.

>- They can

require a great

hatchback of a

>* They can

easily

amount

of space in the backseat, trunk, or

car.

be stolen once a

thief

breaks into the vehicle.

>" Enclosed woofers and subwoofers must be mounted in a location where they won't become a dangerous projectile in the event of a car accident.

(J)-

Amplification Dedicated external amplifiers Advantages >- The loudness

of the audio

can be customized to

suit

your needs.

>• Dedicated external amplifiers are built to handle much more continuous power and heat than the other types of amplifiers. >* One or more dedicated external amplifiers are necessary to provide large amounts of power, such as for heavy-bass and competition systems.

>* Many have

built-in

tunable crossovers.

33

ow and where

to

choose your audio system

L^k^L^k^

Disadvantages >* These amplifiers are much more expensive than purchasing a highpower head unit instead. >* Depending on the power consumption of the amplifier(s), the load of the other accessories on the power system, and the total power output of the vehicle's alternator, you might be forced to upgrade the alternator.

Equalizer/amplifiers

Advantages >* Equalizer/amplifiers are very convenient

if

you plan

to purchase

an

equalizer.

>* They can be mounted >* They are

in the dash.

relatively inexpensive.

Disadvantages >~ They are not designed for

to withstand large

amounts

of heat

and power

extended periods of time.

>* They cannot reproduce audio as accurately as nearly any dedicated external amplifier.

High-power head

units

Advantages

>

A

high-powered head unit requires much

less

space than a separate

amplifier.

>-

A

>"

It

requires less installation

>-

It

requires less space than a separate amplifier.

34

high-powered head unit costs only head unit.

slightly

more

work than a separate

that a

amplifier.

low-power

Disadvantages >* Only the highest-powered

units will provide

more than 25 watts

(each)

into four different channels (speakers).

>*

If

the amplifier

need

(jfy:

is

damaged, the

entire, costly

head unit/amplifier

will

to be repaired.

Conclusion Hundreds of

different car stereo

component models

are available,

and

without keeping abreast of the recent information, you can easily get

lost in

The special 1994 directory edition of Car Audio and 863 different models of dedicated amplifiers! Those are

the sheer numbers.

Electronics

listed

merely the models that were being sold by the manufacturers in 1994; hundreds of other models have been sold and discontinued in years past, and hundreds more will be available in future years. If

you are interested

in car

audio and plan to upgrade your system

more

in the

on the and save all of the copies. If you are interested in purchasing used equipment from the 1980s, you probably won't find the equipment covered in any of the back issues of the car stereo magazines. Remember, hightechnology car stereo is only a few years old. Most of these magazines are still in their infant stage. For information on the older equipment, check at the library for back issues of Audio and Stereo Review.

years to come, be sure to subscribe to one or

of the magazines

topic,

Remember,

the keys to success in purchasing most anything are

good

information, level-headedness. and discernment. Don't be blinded by amazing

and expensive brand-new technologies or by dirt-cheap prices. Buy the best equipment that you can for the money that you are willing to spend.

quality

35

Head

units,

equalizers, signal processors, and

changers The

heart of any sound system

is

the head unit, the source of audio for any

auto audio installation. The head unit

system

(a receiver,

cassette deck,

is

a source of audio for the entire

compact

disc player. MiniDisc player,

player) that also controls the audio with various settings (faders, noise

suppression

36

circuits, etc.).

DCC

Head

B)

The head

units

unit

is

the standard source of music (with buttons and knobs that

control the music) in the car. Normally the head unit

dashboard, although of convenience

m

it

can be mounted

is

mounted

in

the

other locations with lesser degrees

in

and usefulness.

Receivers In the not-too-distant past, nearly

buttons.

No

every car had a receiver

in

it.

No

confusing

multifunction knobs to contend with. Just one knob for tuning

and a second knob for on/off volume control. If you were a real fancy twostepper, you had the folks in Michigan install a radio that could receive AM and FM.

Times have changed. These days.

don't

I

know

of

any companies that

aftermarket car receivers. For that matter, there wasn't

much

in

the

sell

way

of

aftermarket car stereo sound systems before about 1975. There were a few cassette

and 8-track players

available,

and

that

was about

common

it.

So over

the

and aftermarket applications, all radio-only units are factory installed. There's got to be an exception to this rule somewhere, but don't know of it. If anyone has an years, although cassette players are very

in factory

I

aftermarket car radio.

I'd like to

see

it

or pictures of

it!

Radio and audio technology Although many people don't understand all of the basic theories behind AM (MW) and FM (VHF) broadcast radio, that's OK for these purposes. Understanding the differences in modulation techniques between these two mediums won't do you a bit of good when tuning in a station on your car's head unit. As a result, the basic information about the standard broadcast bands is not included in this book. I

suppose the same case could be made about

DCC

and MiniDisc technical

information; however, almost no one these days buys a head unit for the quality of the radio, but these other

mediums

are instrumental in

purchasing decision. Also, technical broadcasting information

is

making a contained

in

dozens of books going back 40 years, but DCC and MiniDiscs are cuttingedge technologies, and currently know of no books that cover these I

subjects.

37

Head

units, equalizers, signal processors,

and changers

Although the broadcast basics are not covered within this book, some of the other, newer technologies and options are included. A million and one different head unit features are currently available, in part because a few of

components overlap

the high-end

their features into other types of audio

components, such as signal processors, equalizers, and amplifiers. Most of these functions are not listed here because they are not common in head units and are covered in other areas of this book.

RDS RDS

(Radio Display System)

on a standard radio

some FM it.

None

Instead, this data is

Even though

by

line),

can be received by your radio, and the computer

capable of deciphering and displaying this information.

of the information line

a system where radio data can be received

Instead of merely transmitting music and talk,

being transmitted along with the broadcast material, you can't

technology inside

books

is

radio stations are beginning to broadcast data as well.

this signal is

hear

(Fig. 2-1).

but

it

is

very complicated (stations are not transmitting

could be extremely useful.

The

various

RDS modes

are as follows:

Figure

2-1

The Denon DCT-950R compact disc player with RDS. The RDS is set to the Program Service Name (PS) mode.

Program Service name (PS) The radio

is

currently receiving

is

callsign or slogan of the station that the

displayed.

Program Type (PT) The different radio formats are broken down into 31 The broadcasting station will broadcast its format, which is then displayed on the RDS head unit. This is useful because you can select

different categories.

a format, and the head unit

will

automatically tune a station that

broadcasting that particular format.

38

is

Head

units

Alternative Frequencies (AF) If the station that you are listening to becomes weak and the head unit is set in the AF mode, it will automatically tune the radio to another station with the same format that has a stronger signal.

Program PI code,

Members of various radio networks will have a them as being a part of that particular network. If

Identification (PI)

which

will identify

you store several radio

stations in the

memories, you can use the PI mode to same network if the original

automatically tune to another station from the station

becomes weak and fades

Traffic

Program

out.

identification (TP)

the

If

TP symbol appears on

unit display, then that particular radio station also provides

Announcement

Traffic

mode, the radio traffic

head

will

information.

the head

traffic data.

identification (TA) With the head unit set to the

automatically tune to a station that

If

RDS

is

TA

about to broadcast

you are listening to a cassette or a compact disc, the preempt the recording to broadcast the traffic

unit will automatically

update.

Clock Time (CT) Rather than controlled by the time that

is

set

your

own

clock, the clock

can be

transmitted by the radio stations, for

more

precision.

This amazing technology horizon:

is

here right now.

it's

Philips has a series of four.

more than just glimmering on the edge of the Denon has a series of three RDS head units and Blaupunkt's Houston cassette head unit also

DCC systems that are technology is presently "cutting edge," and it has not become popular across the auto audio market. Even with its many virtues, if the majority of radio stations don't find that it's worth switching includes an

RDS

system. Like the MiniDisc and

subsequently described, the

RDS

over to an ultimately

fail;

RDS

system, then

however,

if

it

the

to switch over, the system will

won't ever gain acceptance, and it will head units sell and the stations continue

RDS

become

a standard.

With most high technologies, few people consider the potential damage that they could cause. Although RDS systems are amazing and handy. I'm worried about some of the side effects that might occur as a result of their use. For example,

if

people want to hear jazz. RDS will allow them to listen to a jazz no matter where they go in the United States, and at least a few

radio station

other parts of the world. That's convenient, but not particularly enlightening.

know about the genre has been from tuning through the radio and from being forced to listen to it for hours

I'm no country music fan, but most of what

1

39

units, equalizers, signal processors,

ead

and changers

time while working a construction job. Listening to other styles is and enlightening. Other fears that I have with this system are that

at a

interesting

radio stations

forced to adhere to a specific popular format and. in

will feel

homogenize the overall sound of American broadcasting, which is already quite bland. And what if radio stations start programming the names of their advertisers to appear on your display, along with their callsign or slogan? Weve stomached so much commercialization already.

turn, further

Loud function The

is becoming fairly typical on home and mobile audio The loud button functions as a bass and midrange booster; press

loud function

systems.

Human

and the music punches through with a much thicker sound.

much

has a

higher threshold for audibility at the lower frequencies.

it

hearing

As a

you normally listen to music at low volumes, it will sound thinner than if you rocked the car. To compensate, manufacturers added this circuit so that music could be faithfully reproduced, whether or not the volume was high or low. Because of its purpose, the loud function should not be used if the volume is already cranked up. result,

if

Automatic radio muting and control circuits Some companies have added circuits to alter the

you tune will

various automatic radio muting and control

reception quality of broadcast stations. With

off of a station or

if

two

play static or interference. In

that

weak

a

if

signal or

no

signal

is

head

basic feature

units have.

level,

is

it

heard

in

is

When

if

static.

the automatic stereo/mono switch, which nearly

if it is

all

above a certain below that predetermined level, it will be

a stereo signal

put out in stereo;

mono

radios,

detected, this circuitry will automatically

reduce the volume of the radio so that you aren't blasted with

A more

some

each other, the radio other cases, head units have extra circuitry so stations are overlapping

so that the extra noise

is

received that

will

is

not be heard. In another system.

the higher frequencies are gradually rolled off as the radio signal strength

decreases so that the interference

will

be

less noticeable.

Power One

very important feature of every head unit

of putting out to the speakers.

Some

is

the

power

of this information

is

that it is capable covered further in

chapter 3. which features dedicated power amplifiers. Head units vary greatly in the amount of power that they can deliver to a set of speakers. Because

power

amplifiers can be built into smaller areas as high technology continues

to miniaturize

components, modern head units are capable of putting out far possible just a few years ago. If you listen to music at

more power than was

40

Head

units

lower levels, you should have no problem finding a head unit that will satisfy your volume requirements, and you won't even need to buy an amplifier. On the other hand, some head units are only capable of producing a line level output, and others are rated at only about

To be very

the four channels.

useful, these

4-W

output (or less) for each of low-pcwer units require a

dedicated power amplifier.

Mute Mute

is

a very handy do-nothing function. Press

eliminates the audio from the head unit. Press

immediately. Mute

down

and

it

automatically

convenient because you don't have to turn the volume power when you want to say something important to a stop at the bank drive-up window, or talk on a cell phone.

is

display

Although

it

isn't

a function in

and of itself, the LCD (liquid crystal display) is head units. The LCD can be built for much

of the high-end

necessary for

all

more

and complicated applications than

specific

displays.

DCC

it

again and everything returns

or turn off the

passenger, need to

LCD

it

As

capabilities.

Compact

LED

(light-emitting diodes)

a result, for complicated head units such as those with

LCD

RDS

and

displays are necessary.

disc changer controls

With compact disc changer controls, a cassette head unit can control a compact disc changer that is mounted in the trunk. These can vary from manufacturer to manufacturer. Before you buy a system of this type, make sure that the head unit and compact disc changer are compatible.

Preset memories

One

of the most convenient applications of computer technology that has been applied to radio is preset memories. In the analog era. car radios had several pushbuttons and, with some work, you could program each one to move the dial to a certain point whenever you pushed the button. Now you can quickly program a number of different buttons, and each will immediately put you on the exact frequency; the old mechanical pushbuttons often varied in frequency each time you pressed the button and required slight

manual tuning

for best reception.

Scanning With the scanning function, the head unit will tune through the radio band that you have selected, and it will allow you to hear the different strong radio stations. Like many of the features here, the scanning function varies a bit

41

Head

among

units, equalizers, signal processors,

different manufacturers. In

for a brief

on.

When

amount it

of time to allow

hits the

end

some you

cases,

it

finds a strong station, stops

to hear what's on,

only be reactivated

will

Remote Some

and then

of that particular broadcast band,

cases, the scanning function will stop every time that It

and changers

if

it

it

it

moves

stops. In other

finds a strong station.

you press the button again.

control

deluxe head units have a remote control so that you can just press a

button to change anything. About the only time that remote controls are

used and are useful

and you need

is

when

to control

it

a

compact

disc player

while driving.

I

standard head units because usually

off for

is

mounted

in

the trunk

can't see this feature really taking all

of the controls are already

would be great if you could control the head unit in someone else's car with your remote control. What a great plot for a movie; the antagonist follows someone and keeps changing the radio station to "The Grateful Dead Hour." The person tries to fight it, but gradually succumbs to the tunes, falls asleep, and takes out a rest stop.

within arm's reach. But

it

Pullout head units and detachable front panels from chapter

head

and detachable front panels (also you live in an area with a high crime rate. Pullout head units allow you to pull the head unit out by a handle and quickly disconnect it whenever you stop somewhere that you think it might be at risk (at work, a motel, an airport, etc.). With the detachable front panel, all Recall

known

1 that pullout

as faceplates) are of great value

units

if

of the control circuitry

is located in a single panel of the head unit. Just pop it and you can stick it in your pocket and walk away. In the meantime, only a useless black box remains until you snap the front panel back on.

off

Fader The fader

an

infinitely useful control that determines the amount of put out from the front or rear speakers. By pressing the button or turning the knob, you can focus more of the power to the front or rear. This is great if you want to play with the sound stage and fill the entire is

volume that

is

if you have a sleeping keep from waking him or her.

car with audio or

child in the

back seat and want to

Local/DX control The local/DX control can attenuate

the signals that are received by your head you want to hear local stations without the problem of overloading the front end of the radio and having some radio stations splatter across the band, then you should set the control to the local position for attenuation. If the signal is weak, then switch it to the DX position and the signals will no longer unit.

42

If

Head

be attenuated. This control

is

particularly useful

if

you

travel

units

and are

frequently in both cities and minor-market radio territories.

Audition The audition function

is

unit (Fig. 2-2). This unit

a

is

new

feature found in the Pioneer

basically

an entertainment center

FH-M75A head

for your car.

The

audition function is a karaoke feature that cancels the vocals out of music so that you can sing lead. You might have fun owning one of these head units, but never carpool with a person who has one!

Figure

B

C

Several different cassette head units, showing the different features.

D

mm 1

1

Jl

.

1

-»6

L

43

2

2A£c

2-2

££££££££££££££££££££££££££ equalizers, signal processors, and changers Head units,

Cassette decks Cassette players have been around for so long that most everyone seems to them for granted, but they are still vastly popular. With the advent of the

take

DCC

and the MiniDisc, they are increasingly becoming the forgotten new developments in cassette technology have been occurring, other than with the DCC cassette, which is generally considered to be an entirely new medium, not an improvement of an existing one. Most of the technological advances in cassette technology over the past 15 years have been in areas that aren't always noticeable. Clear plastic cassette shells are the most noticeable advancement of the lot. Most of the breakthroughs have involved adding more and denser ferromagnetic coatings, using coatings that are more permanent on the tape, developing tape that is more resistant to stretching, and creating plastics that do not shrink, warp, or melt in the presence of extreme heat that would be found in a car's environment. workhorse. Also, few

Cassette basics have been well covered over the past few decades, but I've included a few here for general reference because this material

more

is

somewhat

background information about the techniques of commercial broadcast transmitting and reception. useful, certainly

useful than

Basics The

cassette

shell to

is

a miniature reel-to-reel tape that has

been encased

in

a plastic

reduce the messiness and the potential for damage to the recording's

sound quality

This case contains two hubs, which are used as

(Fig. 2-3).

depending on which side the cassette is turned pad where the tape contacts the heads of the player, and two guide rollers, which allow the tape to smoothly roll through the shell without wearing excessively.

either take-up or supply reels, to.

The

All of

cassette also contains a pressure

these parts are necessary for a cassette; however, one major record

company produced

cassettes for a while that were so cheaply made that no guide rollers were included. Instead of having the tape roll around the guide rollers,

it

rubbed

its

way around two

design, the cassette squeaked as

Upon discovering much more solid,

this,

I

it

plastic posts.

Because of the poor

played and started to wear out quickly.

cracked the cassette open and placed the reels

in

a

better-quality cassette shell.

Cassettes are reels of plastic film that have been coated with ferromagnetic material. Technically, this material isn't

compound

44

or mixture of iron);

all

some tapes

ferromagnetic

made with any chromium

(i.e..

are coated with

Figure

Inside a

compact

cassette.

dioxide, other types are coated with a mixture of iron oxide dioxide,

and

still

and chromium

others use other elemental compounds, such as cobalt. This

The particles of the manner on a blank tape; become magnetized and face in

material can be magnetized or demagnetized with ease.

recording material are assembled

when you

in

a particular

record something, these particles

different directions, according to the this cassette

recording

is

sounds that are being recorded.

When

played back, the tape passes over the magnetic

heads of the deck. The particular formation of the tape induces a small magnetized tape particles. These signals are then amplified and later turned back into audio by the speakers. signal voltage in the heads, according to the patterns of the

Cassettes were a real challenge for the manufacturers because the tape was

reduced to about half of the width that was used for reel-to-reel tape. As a result, manufacturers had to design much more efficient recording coatings. even saw a cassette prototype from the 1960s that was huge, approximately the size of a videotape! For some time the cassette was snubbed by audio experimenters because the medium simply could not compete with the vinyl record and reel-to-reel tape formats. Later on, by the late 1970s and early 1980s, high-quality cassette technology was openly available, and that helped trigger the boom in car stereo systems.

I

Features Like any audio component, the cassette head unit can contain a different helpful functions that will influence

what you

will

number

of

purchase.

45

2-3

Head

units, equalizers, signal processors,

and changers

Noise suppression The most common noise-suppression techniques for B and C. both of which were developed by Dolby Laboratories. The two Dolby systems are intended to remove the tape hiss that is evident when playing tapes, especially during quiet passages when high-frequency instruments are dominant. This tape hiss is picked up from various sources, but it primarily emanates from the tape head. Whenever Dolby noise reduction is used on a particular recording, the system suppresses some of the frequencies. When the correct Dolby setting is pressed during playback, the frequencies that were suppressed during the recording are now boosted by the same amount as they were suppressed. By using this method, hiss can effectively be reduced. I've never really liked using noise reduction, but then again. I seem to be alone on this issue. recording are Dolby

Dolby

C

is

an improved version

of

Dolby B. but Dolby

B

is

more common

than Dolby C. Both are frequently used on the same units, however.

album was recorded

in

accurately represented) feature of the

head

Autoreverse

One

if it is

it

will

unit you're listening with.

of the

extra features to add to a cassette deck

first

autoreverse. Autoreverse

automatically

If an sound better (or at least be more played back in Dolby B. even if Dolby C is a

Dolby B.

is

the function by which a cassette player will the heads over and begin playing the other side of a the end. With this feature, a tape can play

move

is

tape once it has hit continuously for as long as you can stand

it.

Blank skip With this function set. the tape player will automatically fast forward (or at a speed that is slower than fast forward, but faster than play) the tape when no audio is sensed. When audio is sensed on the tape, the player will stop at that point and resume playing.

Music sensor With player

will

this function set.

you can press

fast

fast-forward the tape until the song ends.

forward and the

Then

it will detect stop and resume playing. Likewise, the music sensor can also be used when rewinding. It will rewind until it detects the blank space at the beginning of the song. Then it will stop

that the tape

is

blank,

and

will

it

and resume playing. Tuner

call With tuner call, the radio will automatically begin playing on the radio frequency that you were last tuned to. This feature is handy if

you enjoy

and

flipping back to hear what is on the had a ground-loop problem on the annoying. Anytime popped the tape out. I

listening to cassettes

radio; however, the

one time

that

I

radio, tuner call was terribly was tormented with a loud whoomp-whoomp sound. I

^\

46

Automatic bias selector The setting of the playback mode (determined by the type of coating on the tape) on the head unit can negatively

sound of a cassette if the setting doesn't match the bias of The automatic bias control on a head unit senses what bias is being used on a given cassette, and it automatically sets the proper affect the

the

tape.

playback mode.

Power load/power eject Power load and power eject both refer to the mechanism that installs or ejects a cassette into or from a head unit. In a unit with power load/power eject, you can enter the tape to a certain point, then the power mechanism will take over and slowly pull the tape

When you

press eject, the motor

will gradually push the you must push the tape until it physically loads into place; when you want to remove the tape, you must press the eject button to physically eject the cassette from the inside.

into position.

cassette back out. With a standard unit,

(J)

Compact Now

that

compact

the novelty

is

disc players discs

have been

beginning to wear

audio medium.

No

off

in

common

use for about a decade or so,

and they are

finally

longer do you hear stories about

becoming a standard

how people have

spent a

few months of wages to gradually purchase 100 compact discs, only to lose them all to a collection agency after the frivolous spending spree. Now that I've seen new discs commonly available for $8 apiece and cutouts for less than $2. know that the compact disc is truly the music medium for the 1990s. I

As you have probably expected, it's now time about how compact disc players operate.

to cover

some information

Basics The compact

disc

is

simply a thin disc of aluminum that

laminate to protect the recording

is

encased

in

a plastic

The music that is to be recorded medium; that is, it must be converted

(Fig. 2-4).

onto compact discs must be in a digital into a massive amount of 0s and Is. When the disc is recorded, much errorcorrecting data and system information (track information and markers, etc.) is also added to the disc along with the music. All of this data must be downloaded, so the aluminum disc is etched with minuscule pits. The pits and the unpitted areas translate as data that represents the Is and 0s.

One

of the key

assembly.

components in a compact disc player is the laser optical a compact disc is running inside of the head unit or

When

47

Head

Figure

units, equalizers, signal processors,

and changers

2-4

Three compact

discs,

showing the

top and bottom sides.

changer, a low-powered laser the tracks of the disc.

The

is

firing straight

up through the player and

but the pitted areas reflect almost nothing back.

tremendously

fast flickering of light

manner but much

faster

The end

result

— coded messages sent

in

is

the

a

same

than done on "Hogan's Heroes." These coded

reflections are received by a photodetector that electrical impulses.

at

unpitted areas of the disc reflect the light back,

These binary

electrical

changes the

light flickers into

impulses are then converted into

analog impulses. Then they are amplified and converted from electrical analog impulses into sound by the speakers.

how

compact disc player operates is tremendously and digital-to-analog processes are extremely complicated, especially when you consider that such things as coding and sampling must also be configured into the system. Sampling is the process by which the compact disc player plays an analog sound, then checks the digital source, then plays another sound. This cycling occurs 44,100 times per second (44.1 kHz), although many players now sample several times more than that per second to make sure that the information being received and played is accurate and not error-ridden. Sampling at harmonic

This information about simplified.

The

a

analog-to-digital

is known as oversampling. Many of the highsample up to 8x the standard sample frequency. At point, oversampling starts to become overkill and the law of diminishing

frequencies (as just described) cost this

compact

returns kicks

Another

disc players

in.

factor, relative

volume, also needs to be considered. Every audio

waveform has a length (the frequency of the sound), which determines the pitch of the sound, and a height (the amplitude of the sound), which determines the volume of the sound. In order for the compact disc player to accurately reproduce music and not wind up with all of the frequencies

Z\

48

Head

units

reproduced at the same volume, the samples are quantized to a 16-bit number between and 65,535. The end result is that every tiny piece of audio that is reproduced by the compact disc can be reproduced at any one of

65.536

different

These codes

volume

that determine various aspects of the

technical operations disc (approximately bits of

levels!

all

require a vast

74 minutes)

information to produce.

amount

compact

disc's

A

of information.

requires in the neighborhood of

If

this

information was

sound and

full

34

much music

Compact Compact

home

held

of digital

and

as they do.

disc changers vs. head units

disc

changers are strange units that have no

real parallels to the

audio market, unlike most other aspects of auto audio

the most part, the of discs.

million

on a standard be placed on 48 5.25" all

computer floppy disc, the selection would have to (13.34 cm) discs! The alternative to this is to determine some sort compression code, which is how DCC tapes and MiniDiscs can be hold as

compact

compact

disc

changer

is

a black

box

(Fig. 2-5).

The changer can be placed at a remote location in the number of discs that can be contained

features to watch for are the

For

number car. Changer

that plays a

within,

whether the changer can be controlled via remote control, and if it has an FM transmitter so that the head unit can receive the disc data without any hard-wired connections.

On that

is an actual head unit Chances are that it has a the outputs are amplified well above line levels,

the other hand, the compact disc unit (Fig. 2-6) fits in

the dash (probably in a DIN-sized hole).

broadcast-band radio

built in.

and the

many

unit includes

pause, stop.

other audio controls (faders, repeat tracks, play,

etc.).

Figure

A compact

disc changer.

49

2-5

w Figure

Head

units, equalizers, signal processors,

and changers

2-6

B Several different

compact disc head units showing the different

features. 2-6A Pioneer 2-6B Eclipse. 2-

6C

Eclipse-

2-6D Alpine. 2-6E

Blaupunkt Division, Robert

Bosch Corporation

D

50

M£JMMMa Head

In

all,

the compact disc head unit

changer

is

is

units

a complete working unit, and the

a drone that requires a head unit to feed into.

choosing between a compact disc changer and a head unit, the decision be based in part on how much money you plan to spend and on whether you want to be able to play both cassettes and discs. If you have the money, then you should go with a cassette head unit that sports CD changer controls In

will

plus a compact disc changer. If you don't have the money, the other choice would be a cassette head unit and a portable compact disc player that functions through the cassette unit via a cassette-shaped adapter. The cost of a compact disc head unit is presently at least $100 higher (the present approximate cost of a portable disc player) than a cassette head unit of comparable quality.

Features Because of the more accurate music reproduction from compact discs, fewer them to play well. Most of the features are computerized and relate to the manner in which the discs are sorted and searched. extra features are necessary in order for

Number

The

of discs

CD

player's parallel to the cassette player's

autoreverse function in car and

changers,

is

the

number

home

audio, including

compact

of discs that can be stored in a unit.

disc

Some

many as 18 discs at the same time; even in-dash head units are now able to handle up to three discs at a time. The prime consideration here is the length of time that you can listen to the music without having to pop out the discs. With the three-disc changers, you could potentially listen to continuous music for 2.5 hours. changers can handle as

compact

disc

Disc access time Disc access time refers to the amount of time between a disc being inserted or changed and when it begins to play. This figure to vary quite a bit in meaning from manufacturer to manufacturer. Even so. the times would only vary by a few seconds. If you have to brag to your friends about how your changer can access discs 1.26 seconds faster than theirs, then you really need to get out

seems

more

often.

Random

When you

boatload of discs into a changer, it is function. This feature will pick out tracks at random from any of the discs. Random access isn't quite as

access

interesting to hit the

exciting

when used on

old favorite a

pile a

random access

a 1-disc head unit, but perhaps

it

will

spice

up an

bit.

51

TggJfJJt

Head

units, equalizers, signal processors,

and changers

fiiiil The

scanning few seconds of each song. After it moves through the entire disc, you can choose what songs you want to listen to. Or you might just choose another disc. Intro scan

intro scan executes similarly to the radio

features. Press the button

and

it

plays the

first

Repeat The repeat function allows you to repeat the track or the disc that you just listened to.

compact

Changer remote control remote controls so that

Some compact it

is

disc

possible to have

changers have their

some

own

of the useful

programmable features that are otherwise only found on head units. Most of the features that are on the remote controls relate to the playback of the discs, but remote control is still a handy feature.

DAT decks market DAT (digital audio These decks were exactly what the name implied a cassette-type tape deck that could record audio digitally. For the first time, the consumer could record at approximately compact disc quality. As a result, many of the commercial labels were worried about the outcome of having a medium on the market that could readily duplicate albums so that each generation of recordings would be indistinguishable from the first. Because of these potential problems, the DAT recording decks were held at bay for some time before they reached North American consumers. In the late

1980s

several

companies began

to

tape) playback-only decks and recording decks.

—

Although the DAT was revolutionary, the prices remained very high on the equipment. Few people were ready to shell out the money for an expensive deck. If they wanted less-expensive digital sound, the compact disc was the way to go. The major benefit of DAT was that it could make perfect digital it was more useful at home than in someone's car. Also, make DAT tapes the same size as standard cassettes, they were

recordings; thus, rather than

made

at a different size,

and the two were not compatible.

Evidently the manufacturers

felt

that they could create a

new medium

that

would displace the cassette and cause millions of people to purchase new tape If this was the plan, it backfired. The general public stayed with the standard cassette and accepted the compact disc. DAT decks only received

decks.

widespread use

in

professional applications, such as in broadcasting,

journalism, and studio recording,

52

where perfect reproduction

is

essential.

Head

units

By the 1990s, the MiniDisc was being readied for the marketplace. With the obvious advantages of the MiniDisc for mobile use. the mobile DAT decks were quickly dropped. In the meantime, the DCC (digital compact cassettes) hit the market and effectively killed the

DAT

in

DCC is a digital cassette that is fully compatible with DCC deck can play a standard cassette or a DCC tape.

The a

Considering the number of

DAT

the public domain.

standard cassettes;

decks used within the several professions

mentioned earlier, the DAT will probably survive for 10 or more years until companies upgrade to more compatible mediums; however. DAT mobile decks are now history for the most part, along with swallowing goldfish and squeezing 20 people into a phone booth.

(J)

MiniDisc players Not being the type

to travel to the

consumer

electronics

shows or

abreast with the latest technological breakthroughs in the world.

to keep was the Sony I

when saw an eight-page magazine advertisement for MiniDisc systems. At this writing. Sony has a car MiniDisc receiver, a car MiniDisc changer, two home MiniDisc player/recording decks, a MiniDisc Walkman, and a MiniDisc recording Walkman. Also. Sanyo (Fig. 2-7), Aiwa, and Clarion have produced auto MiniDisc head units and changers. surprised

I

Figure

The Sanyo MDR-300 MiniDisc head

advertisements, the MiniDisc

In spite of the

technology

(Fig. 2-8).

At

have not seen

MiniDisc, and

I

But with any luck, the world

medium

in

still

it

for sale in

is

somewhat

like a quarter-scale

disc case. In this sense, the relationship is

will

sing the praises of this

new

the mid to late 1990s.

The MiniDisc MiniDisc

just a new, promising few people know about the any mainstream stereo or

is still

this writing, relatively

music

outlets.

unit.

the

same

CD, locked

inside a floppy

between the compact

disc

and the

as that between an open-reel tape player and the

53

2-7

units, equalizers, signal processors,

cad

Figure

Z-o

and changers

4-channel (20 watt x 4) high power

Miniature tuner

with state of the

Integrated cooling

AMPS

fan system

art

technology

CD Anti-shock

changer

read-ahead

controller

buffer

circuitry

memory

circuit

Bassxpander circuitry

Dual color

Easy loading

illumination

slot-type 3-disc

MD changer

controls

Credit-card size

remote

LCD

Full-panel

detachable security

readout

scrolls artist

and track name

An

internal view that

head

unit.

shows the features of the Sanyo MDR-300 MiniDisc

Sanyo

cassette tape player.

The

protective cartridge

is

an important advancement.

This means that an entire commercial recording from an artist will fit onto a 2.7" x 2.7" (6.86 cm x 6.86 cm) disc. Unlike the CD (or the record, which the

CD

replaced), the disc doesn't

placed into the playing device; just

and

One

that's

need

pop

to be pulled out of

its

case and

the whole package into the player,

it.

serious problem for the music enthusiast

is

"What

will

happen

to the

cover art and inserts for these commercial albums?" The MiniDiscs that have been shown in the advertisements only show the cover art reduced to little

more than

a 2" (5.08 cm) square. This would give MiniDiscs

all

of the artistic

would avoid purchasing commercially recorded music that lacked liner notes, complete lyric transcripts, and artwork. Indeed, that was (and sometimes still is) one of the factors that appeal of an 8-track cartridge. Yuck.

54

I

WMMMMMa Head

influences in

my

purchasing records over CDs. Hopefully, a nice booklet

units

will

be

the package along with each MiniDisc.

and the computer-disc-style case are the only positive the? compact disc. The major difference is that the MiniDiscs can be recorded upon over and over and over again. Sony's laboratories say that a MiniDisc can be recorded on more than 1 million times and not show any degradation in quality. This reliability is based on the fact that the disc is digitally encoded and optically read by a laser. No parts or heads wear against the recorded material and eventually But the smaller

size

physical differences between the MiniDisc and

ruin the surface. In fact, MiniDiscs are claimed to be virtually indestructible.

The manufacturer

says that only a combination of laser and an

electromagnetic signal can erase the tracks, so you won't have to worry

about the discs being erased while

sitting in the

sun or on top of a set of

speakers: however, you should not test the limits of the MiniDiscs and feed

them

dog

just because the manufacturer says they are virtually For that matter, you might want to be as careful with MiniDiscs in the car as you would cassettes; although the material wont erase, the disc's cartridge could curl up in a back window sauna.

to your

indestructible.

For years, some audio manufacturers worked toward developing recordable discs; however, the technology just wasn't available at a reasonable price for consumers. The result would have been something like cutting your

compact

own master

Now

record for any songs that you wanted to record off the radio.

MiniDiscs

fill

that technological void.

MiniDiscs are available with two different types of disc materials. Commercially produced albums are recorded on what look like miniature CDs inside of a standard MiniDisc plastic case. Prerecorded commercial albums, which use laser-disc material, cannot be recorded on. If you want to record on a MiniDisc. you will need to purchase blank discs. am curious as to why the manufacturers are using two different disc materials. If the recordable MiniDiscs are virtually unerasable, then why are commercial releases recorded on compact-disc material? It shouldn't have anything to do with controlling potential album bootleggers because a compact disc is easy to copy. It does raise questions, at least in my mind, about the reliability and the potential of accidental erasure of MiniDiscs. In a few years, the buying I

public will find out just

how

well the recordable MiniDiscs retain their

imprinting over time.

One problem

with the MiniDisc format

do they

of that music

fit all

is

the

flip

side of the question;

onto such a small space?"

In

order to

fit

"How

the

55

r*

ead

units, equalizers, signal processors,

and changers

recording time on, they were forced to compress all of that digital information into a 2/4" (6.35 cm) diameter disc. Using a special digital

compression technique, the system purges the audio frequencies that are above and below the human hearing range. By reducing the overall width of the audio, less space is required to copy that information, and more music can be recorded in the same amount of space. In the case of the MiniDisc, more information can be recorded in much less space.

There is

is

when the disc human hearing

a problem, though, with removing those frequencies

recorded. Considering that the frequencies are out of the

range, theoretically, there should be no decline in audio quality. But this

is

work on paper sometimes doesn't in real life. The general consensus has been that MiniDiscs don't sound quite as good as compact discs, but that they sound much better than the average cassette. That being the case, an audiophile would be bothered by this slight difference in audio quality, but you might not even notice. the real world, and what might appear to

One

of the positive aspects of the digital technology

player

will

mark the

immediately

compact

is

that the MiniDisc

you have recorded. Then you can any track on the disc, just like you would with a

listen to

different tracks that

disc player.

This same technology produces flexibility of digital disc

some amazing

results

when coupled

with the

recording. Tracks from any part of the MiniDisc can be

move up in order. For example, maybe you recorded 32 songs on a MiniDisc and you decide that you don't like the nose flute song that was recorded on track 8. You can delete track 8, and track 9 becomes track 8, track 10 becomes track 9, and so on. erased, then any tracks that follow the deletion

the nose flute song (formerly track 8) lasted 2:33, then you have an extra 2:33 of space left on the disc. Maybe you then want to round off the disc with a wacky song by Secular End, just to scare your friends. You have 2:33, plus whatever space was left over on the disc from before. This new song becomes track 32. This feature would be very handy for someone who records cassettes or records and then decides to eliminate different songs from the disc recording. If

Along with these wonders of digital recording come other little touches that add to the convenience of MiniDiscs. For example, the fixed-position (car and home decks) feature is an electronic display that shows the song title and track number of the song that is being played. This information is all stored a disc table of contents, along with the title of the disc. The recording MiniDisc decks have a computer keyboard so that you can enter pertinent

in

56

Head

disc

and song information onto the

disc that

you are recording. With

units

this

system, you could record your copy of the latest album by PiA onto a MiniDisc and type all of the song titles, which will appear on the readout of the deck every time that you listen to the album. This information can be

changed, so

if

you misspelled a song

the information

will

title

or decide to eliminate a song,

all

of

update correctly.

some real advantages, especially when used for mobile or portable applications. For people with large collections of compact discs or even records, it would be much less risky to record these albums Obviously the MiniDisc has

onto MiniDiscs and keep these copies in the car. That way, even if your car were robbed or if it fell into some other disastrous situation, your masters of the music would still be safe at home. Also, the MiniDiscs are smaller and much more convenient than a disc to pop in and out of a deck.

Because MiniDiscs are relatively new and have not yet gained any sort of market acceptance, the future of this medium is still in question. In spite of the many apparent benefits of the MiniDisc, no one wants to spend hundreds of dollars on a deck, only to have it become obsolete in two or three years; ask any owner of a Beta video deck or of a videodisc player. Fortunately for the potential MiniDisc owner, this new technology has more advantages and possibly less competition than the extinct mediums of 15 years ago. in the market, it will have to mediums. Overall, it appears that the main competitors of the MiniDisc are the compact cassette and the Digital

In

order for the MiniDisc to find a place

displace

one

of the already accepted

Compact Cassette (DCC). As far as car audio is concerned, the MiniDisc also has the potential to displace some of the compact disc decks, but they aren't nearly as

One

common

as cassette decks.

feature of the MiniDisc that I'm sure will have the support of the

manufacturers different tracks

is

tied in with the table of contents

on the

disc.

Some

system of documenting the is used in an attempt

of this information

to control violations of the copyright laws by people

who

bootleg

commercial albums. This copyright-protection information allows a MiniDisc doubt to be recorded, but it will not allow you to record a copy of a copy. that this system will do much to stop the recording "pirates" because they will opt to use compact discs as their master copies instead. Still, it is a I

measure against these copyright violations, so I'm sure that the medium receive a great deal of support from the major record labels.

will

Because of this support, the MiniDisc looks like a great choice for a consumer deliberating over a deck system for the car. But like any new

57

Head

units, equalizers, signal processors,

and changers

technology, the prices are bound to be outrageous for several years are currently at about

$600

to

$1000

—

the market grows and

until

competition drives these prices down. Unless you have a handful of cash that has no place to call home, keep an eye on the MiniDisc market, and pick up

when

a system

become reasonable

the prices

for

your budget.

1 DCC decks As

two new technologies

stated in the last section, the

that will be

competing

over the next few years to displace the compact cassette as king of the audio

mountain are the

Digital

Compact

Cassette (DCC) and the MiniDisc.

Physical aspects and differences

DCC

Physically, the

another step is.

in

looks

like

a standard

Although the shape of the cassette

The

considerably. for

compact

cassette that has reached

the evolutionary ladder, and in a sense that's exactly what

shell

is

is

the same,

a thick plastic that

is

it

it

has changed

tougher than the grade used

commercially recorded compact cassettes.

Unlike the completely bilateral nature of the compact cassette, the decidedly one-sided.

cover panel

is set;

the surface,

it

tape.

Then a

is

The top

side consists of a flat surface,

instead of just being a photographic label that

actually a sort of cassette card that

clear plastic panel

is

is

DCC

is

where the album is

affixed to

placed on the

DCC

locked in place over top of the card.

The

add to the overall strength of the DCC tape, and it will also protect the artwork so that the album covers won't all be looking scuffed after a year of use, like an old 8-track cartridge. Also, Philips says that the DCC tape shells are now constructed from materials that are more resistant to heat, which makes this a great medium for use in auto audio systems. Indeed, the look and feel of the plastic is reminiscent of the standard panel

plastic

compact

will

cassettes that are

made

for auto use.

side of the DCC tape is primarily a blank, flat, black piece of except for a piece of metal that is simply known as a slider. The

The other plastic,

a protection device that covers

all openings to the cassette to from entering the shell and to prevent other objects, such as fingers, pencils, and the like, from entering the bottom of the housing and damaging the tape. The metal slider is springloaded, so if you push it open, it will immediately snap back after you release the pressure. In this respect,

slider

is

prevent

dirt

the slider

is

openings

in

58

very similar to the spring-loaded metal guards that cover the 3.5" computer floppy discs. In addition to protecting the tape,

— Head

units

MaW»NNN? the slider also covers the two tape-reel hubs that are only accessible from the

underside of the

DCC

those on a

shell, like

VHS

videotape.

The DCC tape cases are completely different from those that carry standard compact cassettes. Obviously, the slider prevents DCC tapes from fitting into standard cassette cases, so stronger and especially

if

more

new

cases were designed. These cases are

do cassette cases recycle as a #1 or a #2

("Urn.

much

than standard cases, so that's a definite advantage you have sat on or dropped your cassettes on a concrete floor. solid

plastic? ")

DCC cases are open two places: on one of the large flat spaces so that the album cover can show through and at the top so that you can slide the tape into the case. at the

DCC

You

just slide the

bottom after cases remind

it

DCC

tape into the case

has been completely inserted.

me

until

interesting idea, but they didn't protect the cassettes

they would no longer lock the cassettes I

clips in place

of the old heavy-duty slide-in-and-lock one-piece

cassette cases that appeared for a while in the early 1970s.

extensively.

it

In this respect, these

in

from

They were an

dirt

and

dust,

and

place after they had been used

wonder how long it will take before the DCC tapes no longer and go sliding all over the car whenever the driver takes

lock into their boxes a tight curve. This

assembly, but

is

it still

a small pet peeve for such a well-made and sturdy

might be annoying.

Although practically everything about the DCC tape is like the cassette with a post-space-age twist, one thing that remains the same is the tape. Good ole plastic tape with a ferromagnetic coating. According to Philips, the tape will all

doped

be standard videotape with a coating of chromium dioxide or cobaltferroxide. The other tape specifications are that it will have a total

thickness of 12

wide,

like

um

and the tape

will

remain 3.76

mm

(approximately 0.15")

standard compact cassettes.

Although the recording tape is the same, even the manner in which it is picked up and decoded has changed. The tape no longer slides along overtop of the tape heads; instead, the tape is pressed in against the tape heads, locked in at the top of the tape, and wrapped around at the bottom. This technique allows the tape to make more complete contact with the tape heads. Also, because the tape isn't just floating overtop of the heads, it will always be tracking perfectly and not straying from side to side (azimuth error). In standard cassette recordings, the varying position of the tape can cause some variability

in

audio quality.

Philips names for the components responsible for correcting azimuth problems are the Azimuth Locking Pins (ALPs) and the Fixed Azimuth Tape

The

59

R

Head

units, equalizers, signal processors,

and changers

Guidance (FATG) mechanism. The Azimuth Locking Pins (ALPs) are two pins from the back side and lock it against the heads (Fig. 2-9). On the other hand, the Fixed Azimuth Tape Guidance (FATG) mechanism is the set of edges that guides the tape and makes sure that it moves across the tape heads in exactly the same position each time. In spite of all of the technical-sounding names for these components, they are quite simple. that pull the tape in

Figure

2-9

FATG*

Reference surface

*FATG

Fixed azimuth tape guide

*ALP

Azimuth locking pin

A

view of the tape wrapping around the head of the Philips

DCC player.

Philips

One

most important physical and electronic aspects of the DCC and analog playback heads are integrated into a single head. The DCC assembly for auto head units consists of two sets of head of the

system

60

is

that digital

Head

elements

in a thin-film

units

assembly: nine Magneto-Resistive Heads and two

Magneto-Resistive Heads for analog playback. In the home DCC recorders, the heads also contain nine Integrated Recording Heads for digital recording.

The

pickup portion of the head is contained on one half of the head and the analog pickup portion of the head is contained on the other side. As a result, both DCC and standard compact cassettes can be played on the DCC players without any adjustments or head shifting. digital

surface,

A

from a heads operate. The tape passes over the flux guide, which is a tiny band that surrounds the MagnetoResistive element. This element is. in turn, in the middle of another band that provides a constant current. The magnetic field from the tape causes the resistance of the Magneto-Resistive element to vary, which in turn varies the voltage that passes through it. The end result is that the varying resistance produces a modulated digital signal. bit of

technical information that

practical standpoint,

is

is

interesting, but not helpful

the system of

how

the

DCC

can play both DCC and DCC system is so appealing (Fig. 2-10). Rather than toss away the old technology because of the upgrade (such as what has entirely happened to 8-tracks and to some extent with records), the DCC system allows you to gradually upgrade your This combination system

is

why

DCC

head

units

standard cassette tapes and one of the reasons that the

audio collection without forcing you to

totally

abandon

it.

Figure

An

internal view of the Philips

head

unit,

DCC 811 DCC

p**©i

61

2-10

&MFMPMF^JFMFJWMF W^^j/P

WJB&MF&JfM^;M £& J& M'

Head

The

units, equalizers, signal processors,

similarity

between

LCD

appears on the

DCC

tapes and MiniDiscs

display of the head unit as a user reference,

also be used to search for tracks (Fig. 2-11).

includes the track number, the

Other lyrics,

artist,

and the

Some title

and

it

can

of this information

of the particular song.

such as background information about the artist and the musics can be displayed synchronously with the music; however, I'm not sure text,

the auto text

DCC

mode

players are capable of such complicated textual displays.

also allows the system to reproduce simple graphics, several

different typeface fonts,

of placing that the

Figure

that they both have

is

information about the recordings. This information

digital tracks that carry

The

and changers

information age of music

Another

if

JKFff

M>'

all

same

and 16

of this information

DCC

tape

will

different colors.

on a tape

The

DCC

system

is

capable

seven different languages so

in

be compatible with listeners around the world.

2-11

The Philips DCC-811

DCC

head

unit.

=

information, the beginning of each song is marked with markers so that each song can be easily located by track number. Reverse markers can be detected so that the autoreverse function can be initiated. After rewinding and fast forwarding cassette tapes through the entire side, was skeptical about the usefulness of this feature; however, the tracks on the side are stacked in two layers, so the amount of tape that must be rewound or forwarded to reach a particular track is seriously reduced. In addition to this

start

I

One

interesting feature

is

the display that

shows the amount

playing and recording time. Holes in the bottom side of the

of remaining

DCC tape

shell

determine the code for the length of the tape. For example, a hole at one position means that the tape is 60 minutes long; a hole in another location means that the tape is 75 minutes long, a combination of two holes means that the tape is 90 minutes long, and the like. The holes indicate to the tape deck

how

Z\

«

long the tape

is,

and

it

can determine

how much

time

is left

on the

tape.

Head

units

As you might expect from a digital medium, the DCC is divided into sections that somewhat resemble a computer-recording medium. The DCC tape is all of the coded audio and the system data. The remaining track contains such things as track and time information, including track markers. The information on the DCC tape is grouped into small, self-contained tape frames that are separated by interframe gaps. Each DCC tape frame contains 12.288 bytes of information, not including the information to

divided into nine tracks; eight of the tracks contain data, the error-correction data,

synchronize everything.

The recorded information on a frame

in

DCC

tape

is

distributed across the tape

a checkerboard pattern. This information

is

spread out so that

damaged. In that case, a dropout a tape frame might not even be noticeable, where it could have been annoying if it occurred with a standard cassette. information

will

not be

To prevent system

lost

if

the tape

is

errors, error-detection

interwoven across the

and correction codes are The tracks contain two

rest of the recording.

error-correction codes that are specifically

known

in

layers of

as Cross-Interleaved

Reed-Solomon Code

in this specific application. According to Philips, this system will correct circular tape dropouts that are up to 1.45 (approximately Vie") in diameter, which would almost entirely cover all eight

mm

audio tracks.

Availability different as the DCC and the MiniDisc are, they are similar in many ways. Both have been introduced at basically the same time, and in general people have not been exposed to them yet. As a matter of fact, while working on this book, had the pleasure of testing out a DCC head unit and calling the local record stores for DCC and MiniDiscs. It was a rare instance when anyone in the business had even heard of either medium. called or visited 14 different music stores in three states and four counties, and none of the stores had them available. The responses ranged from "Are those the little,

As

I

I

new

things?" to

The attendant came back on

at

"Whafs one

the

that? ...

I

claim ignorance!"

store even asked another

line, told

me

worker for assistance; she have DCC tapes for sale,

that the store did

and wanted to know what artists was interested in. Instead of wasting time on the phone call, just drove down. was a bit perturbed to have driven an hour only to find that the store was totally devoid of DCC tapes and I

I

I

MiniDiscs.

63

Head

This

is

units, equalizers, signal processors,

not to say that there

the opposite

is

true, really.

is

no

future to

DCC

The new mediums

and

tapes or to MiniDiscs. Quite

require an extensive period for

more on the market at the

acceptance. This time the stores and companies are taking an even conservative approach because two

same

new mediums

time. Information about purchasing

available

Head

tapes via mail order

is

America at (310) 475-8668. A mail-order features 400 different commercial titles is available.

from the

catalog that

DCC

are

DCC

Group

of

unit installations

Normally a head unit replacement is one of the easier car audio installations which is fortunate, considering that it's also one of the most important. But as with all auto manufacturers, the designs and construction techniques vary greatly between different models and often even just between different years of the same car model. For examples of some of the problems that you might encounter, see chapter 10, which covers the installations of

to perform,

several specific systems.

The

rest of this section

some

covers

of the

most

common

generic points of installing a head unit.

The

point of installing a head unit begins before you physically initiate the

first

installation.

Before

all

of this process begins,

everything that might hinder you.

be sure to survey the car and

Look over the dashboard. Some dashes be removed after unscrewing a few hex nuts

have a single plate that can easily or screws (Fig. 2-12). Others have very complicated assemblies that you want to strangle the incompetent car engineer who designed it.

will

make

For example, my sister's 1990 Chevrolet Beretta has a single faceplate that covers both the cassette head unit and the air conditioning controls. The only way that you could install an aftermarket head unit in this car would be to cut that plate.

The

stereo in that car

was

certainly designed to be the only

system you would ever have! Different cars use a variety of sizes for the head units (Figs. 2-13

and 2-14).

For example, General Motors cars often use double-DIN holes and a shorterthan-normal mounting depth. Make sure that your head unit will mount in the dash properly, or purchase a mounting

kit

so that

it

will

fit

perfectly (Fig.

you have any question about the mounting, call some of the mailorder companies for information. Some, such as Crutchfield, have an 2-15).

If

excellent reputation for technical support.

After you have surveyed the situation, and installation,

64

make

sure that you have

all

when you

of the

feel confident about the proper tools so that you can

Head

units

Figure

A

view that shows how the dashplate and radio of the Suzuki Swift (1 992 and 1 993) can be removed, scosche

perform the

task.

Before you dig into the

installation,

remove the cable from

the negative battery terminal as a safety precaution. Then,

remove the dashboard or the

if

necessary,

around the head unit. This might take some work, so make sure that you have plenty of time and work slowly. If you run into difficulties with removing the dash or the dashplates. don't get frustrated or angry. If you can't go any further, swallow your pride, and take the car to a mechanic to have the section removed professionally. You might not have the tools to remove some of the specialty screws and nuts, the removal cost is low. and it is better than damaging your car's dashboard.

Once

front panel

is out, you can remove the radio and prepare to install the Depending on the style of the hole in the dash, your radio might fit perfectly, you might need a mounting adapter, or you might need to cut a hole in the dashplate. If so. the method described in the first VW Rabbit installation in chapter 10 is simple and relatively easy.

head

the panel

unit.

The very

first

step

is

removing the head

determining the functions of as

many

unit that

is

in this

of the wires as

location

you can

and

(Fig. 2-16).

65

2-1 2

units, equalizers, signal processors,

Head

Figure

and changers

2-13

Stopper

Screwdriver

TOYOTA mounting bracket Screw M2.6 x 4 1

^ Trim

1

Screw M2.6 x 4 p

Screw

Installing fixed

DIN

units.

Sanyo

Some head

units have a pictorial diagram of the wires' functions stamped onto the outside of the radio's metal sides. Write down the color combinations and the wires' particular functions onto a handy piece of paper. Make sure that you also have the manual for your new head unit

handy so

that

connectors In this hole,

you can

off the

you

find the function of

back of the old head

will

probably need to

into place (Fig. 2-18).

66

fit a head unit sleeve. Slide the sleeve you might need to file out the corners of 2-19). Then slide the sleeve into place, and pop the

If it

the mounting hole (Fig. tabs out (Fig. 2-20).

each wire (Fig. 2-17). Pop the and place it somewhere handy.

unit,

won't

The popped

fit.

tabs lock the sleeve in place.

Head

units

Figure

(- 5 15 /32" (139 mm) -,

2-1

«| l-5 2 /i6" (130 mm)-J

—

i

5^/(4" (148

mml-J

Brace or rear strap

Front panel

The

front panel

the ridges large to

can be cut along

on the back

be

if it is

Nut

too

Nut

installed as furnished

Installing shaft

head

units.

san y0

Chances are that the speaker and power connectors wont mate with those on the head unit. You either need to purchase matching plugs or cut them off and either solder the wires together or use terminal blocks. used the terminal blocks because they're easy to use, connect, and

I

disconnect.

Once you have

correctly connected

all

of the wires together, reconnect

the car's battery ground, and test the head unit. Listen closely for crackles

from short circuits or intermittent open circuits, hums, and speakers that are connected to the wrong channels. If you have any of these problems, troubleshoot your connections, and try it again. that result

Once you have

the system working properly, slide the head unit into

mounting sleeve (Fig. 2-21). Replace the dashboard or any other parts of the car that you might have stripped off to reach the head unit's position. Then take a drive in the car and enjoy your new head unit! place until

it

locks into the

67

f£

4

/ Head

Figure

units, equalizers, signal processors,

and changers

2-15 DIN

Two DIN

Shaft openings

Arc-type radio with slave cassette deck

DIN +1/2

The

Double DIN

typical sizes of car

UnitS.

Figure

2-16

head

Sanyo

Car audio receiver

"i

12 pin molex plug Right front

Left front

speaker

speaker

/

-h '

White /black stripe(-)

to ground to fuse box

Gray /black dl ° w

y

,

Blue/red

Red

stri

,

V Left rear

(

T

T

Green/black

Violet/black

stripe

_ (

}

stripe (-)

antenna/AMP

turn

on

A

N R '9 ht

rear

speaker

The Sanyo wiring color code, which different codes that are available.

12 V)

pe

Violet (+)

)

speaker

68

to fuse block (constant

switched

Green +

>

stripe (-)

to auto

+ 12 V Accessory/

\—

—

Gray (+)

White (+)

is

Sanyo

an example of one of the many

.

Head

15

3

13 12

units

14

11 10 9

Figure

8

x

-12VJl+12V- #'-ll - + 12V The various rear connections of the Philips DC-777 head

1

2.

Antenna socket Threaded stud for

unit

rear support

3. Line-out multisocket

4. 5.

6. 7.

8. 9.

Loudspeaker multisocket Loudspeaker multipug

Power supply multisocket Power supply multiplug 12-V supply lead Ground lead

10. Connection for night illumination 11. Switched

12

V

for electronic

antenna or the relay of

automatic-motor lead 12. Permanent 12-V supply lead 13. Switched 12 V for remote supply of a booster/amplifier or an active loudspeaker 14. Multisocket for optional remote-control unit 15. Connection for batteries of optional retractable unit

69

2-17

Head

Figure

units, equalizers, signal processors,

and changers

2-18

Slide the outer sleeve into the hole in the dashboard.

Figure

2-19

necessary, file the edges of the hole to make the outer sleeve fit. Ph,i ips //

'•

amplifier

...

97

rr

«y WMMa m&; t^m

Amplifiers

Figure

3-13

A

company. The

parallel to

all

of this

small

mono

amplifier.

would be the alternator and the battery

in

your vehicle.

The power supply

of

any piece of electronic equipment

is

a device that

regulates and supplies the proper voltages to the various circuits that are

contained within. This definition of a power supply the average nonelectronics-minded person thinks

is

of.

often contrary to what

Before you

start thinking

whoever came up with this term as being a clueless dweeb, think of the power supply for any given piece of electronic equipment as being the '"input" stage, or the stage that supplies power to the rest of the amplifier.

of

Because the power supply has nothing to do with providing the power to the system and everything to do with altering and regulating that power, building a bigger power supply for an amplifier will not solve the problems of having the battery die when the audio system pulls too much power. You will find that the power supply should be built more solidly when the audio peaks above a certain level, and the audio is clipped by the amplifier. In this condition, in which the amplifier is sometimes said to be "current starved," the amplifier cannot instantaneously react and fully amplify to the sudden peaks of audio power that burst through from the head unit or preamplifier.

To

solve the

problem of a "current-starved"

higher-rated capacitors to handle the extra

amplifier, audio engineers use

power

that is necessary for the audio peaks. Capacitors are one of the basic building blocks in electronics.

Z\

98

ier

design configuration

perform a variety of functions (Fig. 3-14). In this up a charge, and they function somewhat like a battery. Rather than completely draining, leaving no extra charge for the rest of the peak signal, and causing the audio to clip, the higher-rated capacitors are filled with a larger charge, and they have enough power stored to be able to dump a sufficient charge to power the amplifier during the peaks.

and they can be used

to

case, the capacitors build

Figure

The top view of the main

circuit

3-14

board of a

well-built amplifier.

Because the "current-starved" condition

is

best avoided,

some audio manuals

of capacitance in microfarads throughout the entire amplifier. This capacitance rating doesn't necessarily mean that an amplifier is better built or that the amp can provide plenty of power to avoid audio clipping. list

the

The

amount

rating merely

the amplifier

is

means

that the

amp

poorly designed, this

to read the amplifier reviews in the

capacitance

A

in

an

has a large amount of capacitance.

means

nothing. In

magazines than to

all.

tally

it

is

much

If

better

up the amount

of

amplifier.

clipping amplifier

is

being overdriven, whether

it

has reached

its

specified

problem because the condition distorts the audio, but because the condition can easily blow out the speakers. The chopped-off waveforms can cause the voice coils in the speakers to overheat and subsequently be destroyed. The only solutions to the problem are to

output or not. Clipping

is

not

just a

99

ft

Amplifiers

either listen to music well within the

mean

listening at lower

amplifier that

means

of the amplifier (which might

volumes than you would

you could use

in

like)

conjunction with the

or buying another

first

one.

Stereo separation Another problem that can occur with the power supplies in amplifiers is interaction between the power and audio stages. Sometimes the audio will draw power from the power supply, but instead of supplying a steady energy source, the voltage

will fluctuate.

The

voltage fluctuates along with the audio

and makes a duplicate audio signal of sorts. This duplicate voltage signal can interfere with the two real audio signals. Of course, there is only one source of power: so, when the audio signal modulates the voltage, which signal

interferes with the audio, the stereo separation will

one magazine locate

it

since

article that fi

r st

I

reading

read several months ago it),

become (I

less

prominent. In

haven't been able to

audio experts isolated the dc power

in

an

operating amplifier, and they were able to demodulate the dc power to the point where the songs were recognizable!

The standard for rating stereo separation in Car Audio and Electronics is in dB at 1000 Hz, which is within the midrange and where the difference is most important. In some of the recently rated amplifiers, the stereo separation has ranged from 33 to 78 dB quite a difference. Even so, stereo

—

separation, although helpful in establishing a great sound,

important as some figures (such as

THD) and some

is

not nearly as

of the features (such as

built-in crossovers).

Stereo separation

ways

is still

a factor for audiophiles to consider.

One

of the best

up the problems with separation between the left and right channels is to use two (or more) mono amplifiers, one (or more) for each channel. Another solution is to purchase one of the high-end amplifiers that solved the problem by building in either a separate power supply for each to clean

channel (such as the Monolithic

mono

achieve virtually the

100

PRO-2000-DM)

same cabinet (such same results (Fig. 3-15).

amplifiers into the

or building two separate

as the Audison

HR-100)

to

Additional amplifier features

Figure

The Monolithic PRO-2000DM mono

amplifier.

Monolithic

J) Additional amplifier features In the

high-tech world of car stereo, a dedicated amplifier

features

jammed

in

than

just

will

have more

the amp's circuits. Today's amplifiers not only

include extra features, but they also put a spin

on some

of the standard,

boring parts, such as the connectors.

(j)-

Crossovers One

power

of the beneficial add-ons to dedicated

amplifiers

is

system. (Crossovers are covered throughout this book, so look

which covers various

filters

and crossovers,

if

a crossover in

chapter 6,

you need more information

about the subject.) Power amplifiers are a perfect location for crossovers, which must be placed between the speakers and the amplifier. Unless the be installed within an enclosed speaker box. they will need to an enclosure and mounted somewhere in the car to prevent bouncing around in the trunk or backseat. crossovers

be

will

built into

A much network.

neater solution

is

to purchase

In addition to the

an amplifier with a

neatness benefits,

some

built-in

crossover

of the amplifier

manufacturers dedicate a great amount of time perfecting their crossovers.

As

a result,

3-16).

some

Some

of the best crossovers available are built into amplifiers (Fig.

of the built-in crossovers are

even tunable, which means that

the high-pass and low-pass positions can be set and altered via a control

knob. This feature

is

match the frequency

particularly useful

because you can tune the crossover to

ratings of your speaker system.

101

3-15

Amplifiers

Figure

3-16

The underside of the Rockford Fosgate Punch 200.x amplifier, showing inputs, outputs,

and the

variable crossover chip.

Number The

of available channels

amplifiers of today aren't merely the in-dash black-box boosters that

Many cars are filled with speakers, and anywhere from one to eight channels of amplified output are available. The number of amplifier channels is nearly as important as the output power for determining what you need.

defined the technology of the 1970s.

For example, if you are in the market for an amplifier to be dedicated to running a single subwoofer that you are mounting in the rear deck, then you would probably be most interested in a mono subwoofer amplifier or a twochannel stereo amplifier that you could bridge for a high-power

mono

output

you are an audiophile who is attempting to maximize the "wall of sound" in the car, you will probably want to place as many speakers around the car as possible. For these requirements, you could get as many as eight channels of audio. If you are just interested in setting up a standard, affordable, but great-sounding system, a four-channel amplifier would be best so that you could mount two speakers in the front and two in the rear. Of course, your channel requirements will be more flexible if you will be using several amplifiers and can add the number of channels. (Fig. 3-17).

102

If

Additional amplifier features

TWO CHANNEL

AMPLIFIER WIRING DIAGRAM

Figure

STEREO

-

TO REMOTE TURN ON

TWO CHANNEL

AMPLIFIER WIRING DIAGRAM

EffiHI

-

MONO

MONO INPUT VIA Y-ADAPTER

—OO

1

fee*

$

MONO OUTPUT

BLACK TO CHASSIS

RED TO BATTERY

VIA

FUSE

PLEASE NOTE;

COLOSSUS USES TWO POWER CONNECTORS: ONE PER CHANNa

TO REMOTE TURN ON

Connecting an amplifier

in

stereo or

mono.

»fonc»

103

3-17

Amplifiers

Plug-in modules Because of the varied requirements of car audio enthusiasts, one company has even developed a line of plug-in amplifiers so that you can arrange an amplification system to suit your tastes. Canton has two chassis available that can hold from three to five of its stereo or mono amplifier modules that will plug into the slots. This system is really sharp, but it works well only if you want to stick with Canton-brand amplifiers; no other company builds amplifier modules to fit into the Canton chassis assemblies.

Gold plating Some

metals are better conductors than others; that

with less natural line resistance. Also, resistant)

some metals

is,

are

than others; obviously, corrosion resistance

given the harsh car environments. corrosion resistance and interconnects

is

maximum

So

the key

method

signal transfer

is

power flows through more inert (corrosion of key importance,

of reaching

maximum

between amplifiers and the

to use connectors that are plated with a material that

is

both

very highly corrosion-resistant and conductive. It just so happens that two of the best metals for these purposes, gold and silver, are also ancient symbols of wealth. So if you want to maximize signal transfer with gold-plated connectors, you will have to pay for it. Like many of the car stereo features, you don't need gold plating to have a much better-than-average-sounding car stereo system, but you might notice a difference years later if the connector started to have a corrosion problem.

i

siize seem like much of a feature until you start stuffing amplifiers under the seats and on the walls and all over the floor of the trunk. A typical amplifier case is approximately 8" x 8" x 2" (20.32 cm x 20.32 cm x 5.08 cm), although the higher-powered amplifiers run much larger than this, and the lower-powered ones are often much smaller. Depending on your car's Size doesn't

make a real difference in which amplifier you you were initially considering an Audison HR-100 amplifier, you might find its 9" x 29%" x 2" (22.86 cm x 75.24 cm x 5.08 cm) size to be intimidating (Fig. 3-18). Then again, if you were ready to shell available space, size could

choose. For example,

104

if

Additional amplifier features

Figure

The Audison HR-100

out the fit

$6000

to

own

amplifier.

one. you might just as soon buy a larger car for

it

to

into!

~E Equalization Although equalizers are more often equated with preamps than with dedicated power amplifiers, a number of those on the market do have some type of equalization system. As you can imagine, the equalizers on dedicated power amplifiers, which are normally stuffed somewhere out of sight and out of reach, are not overly complex. Most are merely a "bass boost" or a "treble

boost" switch that

is

mounted on the

front panel.

The bass boost

control

is

be put into dedicated service with one or more woofers or subwoofers. Some amplifiers have several tone controls that you can adjust for a general type of sound that you want to get from your especially

handy

if

the amplifier

will

system. Other than the bass boost, the equalization controls aren't very important if you plan to also use a separate equalizer.

105

3-18

Amplifiers

(J)

Noise reduction A few

amplifiers

None

of these circuits are the standard

on the market

have built-in noise-reduction circuits. Dolby B. C, or DBX circuits, which are used to decode or modify the audio signals during the recording and actually

playback processes. Instead, these amplifier noise-reduction

circuits are

all

used to prevent ground loops. Rather than decode the information that they receive, they prevent ground loops by using differential inputs that subtract ground noise from the inputs and break the ground loops that induce noise.

Each

company seems

have designed each particular amplifier its own amplifiers because it seems that each company uses a different system. For example, Blaupunkt uses the different

to

noise-reduction system specifically for

HUSH

noise reduction system, Philips uses a

circuit,

and

LA Sound

CMR

(common-mode

rejection)

uses a buffered active noise canceler to eliminate

ground loop noise problems. Not having ever used these products, I can't say whether or not they are effective or useful; however, one audio expert has told

me

that these noise-reduction techniques are very effective, particularly

if

using a high-powered or very complicated system.

Speaker-level inputs Recall from earlier in this chapter that

head

units are

becoming increasingly

25 and even 4 x 25 watt head units are becoming common. What if you want still more power 9 Although many of these head units are high powered, not all of them have line-level outputs. Likewise, not higher powered; 2 x

amplifiers have speaker-level inputs.

If you connect speaker-level outputs on a dedicated power amplifier, you could cause severe damage to your equipment. Of course, it is possible to buy speaker-level to line-level adapters, which are currently available for less than $15 from Parts Express. Depending upon your situation, speaker-level inputs

all

from a head

unit to line-level inputs

could be a very important feature.

Bridgeability Also

recall from earlier in this chapter that an amplifier can produce more power (usually more than twice as much) if the outputs are bridged. This method is particularly useful if you want to bridge an amplifier for dedicated use on either a single (right or left) channel or for a woofer or subwoofer.

106

J?^W^W MFJ?^J MF Mf Mf^W JJ£r^JJJ^J Additional amplifier features

Most dedicated power amplifiers are bridgeable. but about 10 to 20 percent be a factor if you plan to buy one amplifier, then gradually add more amplifiers and put them into bridged service. aren't. This could

(J)-

Thermal and overload protection Thermal protection is the ability of a piece of equipment to shut down or blow a fuse if the circuit is overheating and on the verge of being destroyed. Overload protection is the same thing, except that it protects the circuit against being overloaded/overdriven, rather than against overheating. Nearly

every dedicated power amplifier has both forms of protection. For the most part, the only amplifiers

on the market without these forms

of protection are

the low-end amplifiers that are built as cheaply as possible. Unless you won't

be taxing your amplifier's capabilities and you cannot afford a better amplifier, avoid amps without thermal and overload protection; otherwise, your amplifier could self-destruct before

its

mission was completed.

Gain control Most amplifiers have a gain control knob on the

front panel so that

control the level of amplification (Fig. 3-19). This control

you can

set

it

at a

proper

level that neither

is

you can

useful because

causes the amplifier to be

overdriven nor causes the head unit to be cranked out (causing the signal-tonoise ratio to worsen). Also, amplifiers induce less noise into the audio output if

they are being operated at a lower

level.

(For

more information on

setting

Figure

The gain and

level controls

on the Rockford Punch 200ix ampi

107

3-19

Amplifiers

the gain control

on an

amplifier, see the section "Amplifier level tweaking" in

the latter portion of this chapter.)

and

Practical amplifier tips

tricks

Dedicated power amplifiers are more along the lines of custom units than head units, and their treatment is also more flexible. Of course, you are not if you would be expected if constructing you do have the flexibility to mount the amplifier most anywhere in the car and the ability to adjust the crossover rates and amplifier input levels and the choice of whether to add a stiffening capacitor.

expected to modify the equipment, as

from a

kit. Still,

Installation locations Dedicated power amplifiers aren't the most

difficult pieces of equipment to and screw the amplifier down, and your audio system is in business; however, difficulties do spring up that can cause some slight problems in preparation. install.

Just plug in a few wires,

For an example of preparatory problems, the most

common

installation

power amplifier are either in the trunk or under the front seat. You can mount under the front seat, but depending on how hot the amplifier will get. it might not get enough ventilation. You probably won't know if the amplifier gets enough air until you have installed it and see how locations for a dedicated

hot

it

gets.

and you run the amplifier cranked up and the case gets move it to an open area in the trunk. One exception to this rule is in the case of running an amplifier into a load that is fewer than 4 ohms (normally, these low-impedance systems run at 2 ohms). In this case, you should always install the amplifier in a If

the space

is

tight

very hot to the touch, then you should probably

maximum-ventilation location.

Often the under-the-seat location seat in order to install

removal

is

it.

In

relatively simple.

some

is

difficult

because you must remove the

cases, such as with a

Unscrew a few

bolts,

VW Rabbit,

and then

the seat

pull out the

many other cars have a bench-type front seat that most of the front passenger space. Depending on the size of the front seat and the manner in which it is installed, trying to pull it out might cause numerous hassles. lightweight seat; however, fills

108

Practical amplifier tips

Amplifiers could be car.

mounted

in

other locations

in

and

tricks

the passenger area of the

but in most cases the locations are not the optimum. In-dash or under-

common low-end units that were These models were often combined with equalizers, and they were not known for impressive fidelity. If you are working on a low budget, you might want to find one of these amplifiers and mount it under the dash. Signal boosters were built in odd sizes; therefore, you probably won't be able to find a location in the dashboard for a clean mount. If the sound and low cost are more important than the looks, you would probably want to go with the under-dash mount because it's much more convenient to install and operate. dash amplifiers

("signal boosters') are

especially typical in the 1970s.

Depending on the

size of the dedicated

power

amplifier

and the amount

of

might be possible to mount the amp up in the kick panel on the passenger's side. Not only should the car be roomy and the amplifier be small for this type of installation, but you should run the system at a lower level so you don't cause the amplifier to become hot and burn the space

in the

passenger

power

in

passenger area,

your

car.

For

it

this reason,

you shouldn't mount a dedicated

amplifier under the dashboard. Your system could very possibly burn

the legs of the passenger.

you decide that a trunk-mounted amplifier is the only way to go, you have a few other options and problems. It is very easy to mount the amplifier either on the floor of the trunk or against the back seat, if you have either a pickup truck or a sedan. If your car is a hatchback, then you are stuck with mounting If

either

on the floor or on one of the side walls of the vehicle. To install the on the trunk floor or on the back of the seat, just screw it down.

amplifier

Make many

sure that you are screwing into something that cars are

made

is

The backseats of mount is feasible so

solid.

with dense foam rubber. This type of

long as you use longer screws or butterfly nuts that spread out as you screw them in place. Also, you shouldn't run the amplifier at a level so high that it

makes the

unit hot to the touch:

you might melt the back of the

seat!

sure that you will be mounting the amplifier in an area that is any wires or important auto parts. haven't yet heard of anyone who's done it. but I'm sure that someone somewhere has accidentally

Also

make

clear of

I

mounted his or her power amplifier over or too close to the spare tire in the trunk. The all-important question is whether he or she realized it soon afl doing so or if the moment of realization came on the sh,, wider of a busy interstate highway after unloading a trunk th.it was full of luggage.

109

Amplifiers

Another trunk-mounting option great location, but that

requires

it

have been mentioned

is

the side wall of the rear fender. This

more work than

is

a

of the other simple locations

all

in this section thus far.

you own a newer

If

car.

there might be a layer of carpeting along the inside walls of the rear fenders of the trunk. This material will only get in your

way when you go

to

mount

the amplifier.

Because only a thin

back of the trunk from the outside

steel wall separates the

world, you cannot screw the amplifier directly into place. Instead, cut a thick

piece of particle board or plywood into a shape that amplifier

and yet

will

still

mount on the hole

is

larger than the

in the side wall of the rear fender.

Screw the amplifier onto the board and determine the direction

that

you want

Be sure to place the amplifier in a position that the controls will be accessible. Once you have a position set, consider how the mounting straps it

to face.

should be cut and

out so that they can securely hold the mounting board

laid

in place.

A

typical set of

mounting straps consists of several

strips of

metal with screw

holes that permit placing the mounting board tight against the fender.

You

could improvise and use side supports from a metal shelving unit, or you could cut your

own

or aviation snips.

your

own

strips

Be

from a piece of sheetmetal using a pair of tin snips file off any sharp edges or burrs if you fabricate

sure to

straps.

Then bend

the mounting straps so that they

and ensure a

tight

fit.

You

will

need to

drill

will

fit

in nicely

with the supports

holes into areas near the panel

(such as the floor or a piece of metal that helps support the fender, yet isn't part of holes,

what you see on the outside) to hold it in place. When you drill the sure where you are drilling: otherwise, you might drill a hole into

make

or through the fender.

Next, use a heavy-duty adhesive, such as Liquid Nails, to glue the mounting

board to the trunk straps earlier.

wall.

and screw them

Then

let

While the adhesive

is still

speed bumps, off-road driving, etc.) for because you might bounce the amplifier loose. job isn't necessarily easy, but at least

for the amplifier will

amplifier. (For

110

you

drilled

bumpy drives (railroad the next 24 hours or so

the adhesive set and try to avoid

tracks,

The

wet, add the mounting

to the board, then into the holes that

be as

difficult

it

is

or possibly

more information on

quite simple. Actually, the wiring

more

difficult

than

installing the

cables and cable installations, see chapter

9.

which covers wire,

cable, connectors,

and transmissions systems, and

chapter 10, which covers several specific

M

installations.)

Amplifier-level tweaking When was a teenager, one of my best friends and used to copy albums for each other. He had a good component system for someone in his early teens, and had, well, for a while had my parents" Zenith AM/FM/phono console I

I

I

I

(no recording capabilities there), and later

could use

I

my

parents' average-

grade component system. With an audio system under his

who

belt

and a father

taught electronics at the local vocational/technical school, he was the

He was also very nice and graciously taped me when was unable to record anything in return.

audiophile between the two of us. quite a bit of music for

When

I

he recorded, he would usually use some of those snazzy

effects,

such as

Dolby B or C. and he would be very careful about the levels of the analog dB meters a hair into the red, and he would back the levels off.

—

On

the other hand,

sensitive digital

whenever

LED dB

into the red) of the display.

cassettes

I

meter),

were always low

I

still

keep the peaks

didn't take

It

in

recorded and

me

volume, and

(using a less-

long to notice that

had

I

do record

at the next-to-last

to crank

my

them up

in

LED

(yes,

friend's

order to

hear them: even then the tape hiss would sometimes become quite an annoyance. On the other hand, my friend complained several times about

how pushed

the levels. Admittedly, some of the recording is slightly on high-frequency peaks, such as cymbal crashes. An appropriate that sounds good to the average person is probably between our two

I

distorted level

recording-level choices.

down memory lane for me, this story illustrates an auto audio system. The recorded material, as compared to the background hiss, represents the signal-to-noise ratio. My recordings have a great signal-to-noise ratio; however, often the peaks of my recordings are clipped as the audio goes beyond the sound "ceiling." My More than

just a nostalgic trip

setting the levels in

friend's recordings,

on the other hand, had no trouble with

the levels were well below the

dB

distortion because

"ceiling."

When you set the gain on your car stereo amplifier (or amplifiers), you will be doing exactly the same thing, plus a few extra steps. If you set the gain on the amplifier too low, you will have to turn the volume control of the head unit way up, which will cause more noise to be amplified. As a result, the extra noise will probably be annoying.

On

the other hand,

if

you

set the gain

too high, your amplifier might clip and cause distortion. Chances are,

111

m plifiers

however, that real

problem

it

if

won't

distort,

it

will just

be

conversation in the

car.

The opposite

is

true

volume control up to "10" and the system In order to

if

still

"

1

tape,

compact

This excessive volume

makes

"

it

difficult to

pull

disc, or MiniDisc) that

is

a

hold a

you have to turn the head isn't loud enough.

tweak up the system's amplifier gain,

DCC

cassette,

LOUD!

turning the volume knob up to

unit

out a recording (either

is

representative of the

audio levels that you will be listening to. Turn the level of the amplifier to the "0" position (all of the way counterclockwise) and pop in the recording. If

on the

up so that you can hear the audio volume on the head unit until it starts to distort. Back off the level on the head unit until the audio is no longer distorting. Then turn the gain up on the amplifier until the audio either becomes distorted or is too loud for you to tolerate. At this point, the settings of the amplifier gain are probably close to where you would want them to be, but they might require some final tweaking (as described in the necessary, turn the gain

from the source. Then

amplifier

raise the

previous paragraph).

Jm Using stiffening capacitors in conjunction with dedicated

power amplifiers One

of the hottest fads in auto audio has got to be the stiffening capacitor

(Fig.

3-20). Although

you can

attain

some

definite

system improvements with

a stiffening capacitor in certain applications, there are also

some myths

that

are floating around. Fortunately, stiffening capacitors and the theories behind

them are both

quite simple,

and the

tall

tales are

easy to dispel.

A

stiffening capacitor is merely a very high-valued capacitor that is used in conjunction with dedicated power amplifiers to temporarily store electricity.

When

a large power-drawing signal

peak drains

stiffening capacitor discharges in order to

amplifier.

When

fill

the

the stiffening capacitor unloads,

all

available power, the

power requirement it

of the

helps prevent clipping,

especially in the bass frequencies that require much more power to boost the signal to an appropriate-sounding level. So a sign that you might need a stiffening capacitor in your system is if the bass frequencies distort at high

volumes.

Electrical connections and safety considerations The stiffening capacitor is placed in the power circuit by the dedicated power amplifier (Fig. 3-21). The positive terminal should be connected

112

to

Figure

3-20

Stiffening capacitors: 0.5

farad

(left)

and 1.0 farad

(right).

Figure

j~^k£^ Tattoo

Power Cap

Power Amp

«

Speakers

The

installation

Authorized Paris

the positive lead

(in

L

*w

\

diagram for stiffening capacitors.

Company

the circuit between the amplifier and the battery).

The

negative terminal should be connected to ground. Because the capacitor in

the circuit that supplies

power

is

you should follow the the capacitor's wiring that you did for

to the amplifier,

same wire gauge specifications for the power amplifier. Also, the stiffening capacitor should be strapped

down

to the floor or sidewall so that

it

is

secure, won't tip over,

and won't

short out.

You must be

sure that the polarity

start a car battery

explosion

in

your

is

not reversed

or, just like trying to

jump-

with the polarities reversed, you could have a nasty car.

113

3-21

Amplifiers

One manufacturer specifies that you should charge and discharge the capacitor with a 25-ohm V2-W resistor in line with a 12-Vdc power The

charge the capacitor; the however, you should discharge the stiffening capacitor with that resistor so that it will unload slowly and not all at once. It's not dangerous in itself to have the capacitor discharge immediately, but you'll probably make fewer mistakes if you connect the resistor across the leads, rather than zap them together with a supply.

resistor isn't necessary to

alternator will charge

screwdriver. Just leads or

make

you could be

just fine;

it

sure that you aren't also bridging the capacitor's

in for a

nasty shock!

Although the high-current 12 Vdc from the stiffening capacitors generally not considered to be lethal, they are very dangerous nonetheless.

One

of

my

electronics teachers said that

some

is

of the guys

worked with liked to play practical jokes on each other. These jokes sometimes involved loaded high-value capacitors (but not as highvalued as auto stiffening capacitors). In one case, someone threw a that he

charged capacitor to a coworker; in another case, several high-value capacitors were charged and placed in a drawer full of capacitors; and in the last joke, a charged capacitor was thrown in a toilet while someone was doing his business. The end result was that one of the practical jokers wound up visiting the doctor for second-degree burns and a few other problems. Be careful around capacitors; they can be very dangerous. Because of the dangers of stiffening capacitors, most companies very clearly mark the polarity on the terminals so that you won't accidentally reverse the wires. As an extra safety precaution, Harrison Laboratory even includes an LED to show when the capacitor is charged so that you won't improperly handle a "hot" capacitor.

When

installing the capacitor,

your amplifier

you should keep

it

as close to the amplifier as

you should probably place an insulating cap over the top of the capacitor to prevent the terminals from being inadvertently shorted together. possible.

Some fuse

If

is

close to a highly used area in the car,

audio enthusiasts protect their amplifier and capacitor by installing a

between the two; however,

this practice

only prevents the high current

from instantly reaching the amplifier. Instead of protecting the equipment, defeats the purpose of the stiffening capacitors.

3\

114

it

Connecting several stiffening capacitors together Because the power requirements

for

an enormous competition-caliber system

are so large, you just might need to use several stiffening capacitors in parallel to supply the

necessary instantaneous power to the amplifiers. The

group of stiffening capacitors can either be connected via heavy power cables or via a bus bar. The bus bar is a flat piece of metal that snaps onto the top of the capacitors and greatly simplifies the connection process. Some companies even sell large gold-plated bus bars for expensive, high-powered systems.

Are stiffening capacitors necessary? Like any fad. you have to eventually question are appropriate and

how many

are just hype.

how many The

truth

of the positive

is

capacitors are necessary to prevent distortion at the low frequencies the amplifier

using a

is

power

being driven hard. amplifier with a

Some

more

words

that stiffening

when

of the problems can be reduced by

stoutly built

power supply.

In

other

cases (such as in super-powered competition vehicles), the capacitors are

still

necessary.

One

factor to consider

$60

to

$220. which

distortion at high

is

is

cost.

power

levels.

thundering bass on a budget,

stiffening capacitors run

it

$200 on another amplifier so that it could be dedicated to operating subwoofers. And for the price of three 1-F stiffening capacitors

$100 the

anywhere from remove some low-frequency For people who want high power and might be more attractive to spend that extra

Most

quite a high price just to

or

connected to a gold-plated bus bar. you could easily purchase a Rockford Fosgate Punch 4040 DSM (4 x 40) amplifier, an Alpine 5957S compact disc player, or an Aiwa AMD-50 MiniDisc player. I'd take the toys and spare a bit of volume, but that's just my preference.

The bottom

line is that stiffening

capacitors are essential for competition

boomers, but not necessarily for the audiophile or the average in-car listener. Take some time to listen to your system and get to know it before you shell out the big bucks for those big. shiny cans of vehicles

and

for bass

electrolyte.

(^j)

Conclusion For such an apparently simple device, a dedicated power amplifier is fairly complex. To make matters worse, well over 800 different models were on

115

mplifiers

the market in 1994. In order for the amplifiers to be competitive, companies

have to create a niche with different hardware features to promote their respective angle or angles on the market. Chances are that when you go amplifier shopping, you won't come across half the models that are available. There are just too many for any distributor to be able to sell them all. Unless you contact some of the companies directly, particularly the very small, highend manufacturers, you probably will wind up purchasing something from one of the very large companies that can afford to have their entire line sold by dealers.

116

Speakers Although some elements of car audio and you, speakers should be familiar of electronic sort.

turf.

its

components might be

foreign to

Probably more than half of the pieces

equipment on the market are equipped with a speaker of some as speakers are, there is still a huge difference between the

As common

various grades of quality that are available. 99

speaker

• Wiring

150

-

4-

r C~5

2-0

^

speaker

b^

2-0

power

CZ5

speaker

• with equal

+r

sharing.

& ^

2-0 total impedance

^

in series

4-

c

r

—

k—

+

p

c^>

^ —

Impedance and interconnecting speakers

One

of the easiest and most common examples of wiring speakers in parallel running two 4-Q. speakers in series, but also in parallel with two other 4-£2 speakers that are also in series with each other. This set of four speakers can be run off the same amplifier channel. To determine the impedance of the is

parallel/series speaker connection:

1

(4+4-)

Z7 2

\

20

m"

// /

m"

\}*> 10

/

/ /

*fl

/t

>
t

0.08mH

i

t

f

C A In

Z

6-13

125 250

crossover chart

500 1000 2k Frequency (Hz)

4k

ua/ues for capacitors

mi'tri

8k

and

Z

L

inductors.

case you are scientifically curious, the second-order values were found by

multiplying each first-order capacitance value by 0.7 and each first-order

inductance value by 1.414.

A

chart of values

is

make

also included to

the

value-hunting process even easier (see Table 6-1).

Values for Parts This

in

Various Crossovers,

a 6 dB/octive crossover

is

Crossover

4-ohm

point desired

speaker

speaker

MFD MH MFD MH

Table

This s a 12 db/octive crossover i

4-ohm

8-ohm

me***™

speaker

8-ohm speaker

MFD MH MFD MH

50 Hz

796.7

12.7

398.1

25.5

998.0

32.0

499.0

640

265.4

17.0

665.3

2\ 3

332.7

42.7

32.0

75 Hz

530.8

8.5

100 Hz

398.1

6.4

199.0

12.7

499.0

16.0

249.5

125 Hz

318.5

5.1

159.2

102

399.2

12.8

l') )(.

2

150 Hz

258.4

132.7

8.5

332

7

10 7

166.3

21.3

175 Hz

227.5

42 36

113.7

7.3

285.1

9.1

1426

18.3

200 Hz

1990

3.2

99.5

6.4

249.5

8.0

124.8

16.0

(

|

201

6-1

Filters

Table

and crossovers

6-1

Continued This

202

a 6 dB/octive crossover

This

is

Crossover

4-ohm

point desired

speaker

8-ohm

12 db/octive crossover

is a

8-ohm

4-ohm

speaker

speaker

MFD MH MFD MH

speaker

MFD MH MFD MH

225 Hz

176.9

2.8

88.5

5.7

221.8

7.1

110.9

14.2

250 Hz

159.2

2.5

79.6

5.1

199.6

6.4

99.8

12.8

275 Hz

144.8

2.3

72.4

4.6

181.5

5.8

90.7

11.6

300 Hz

132.7

2.1

66.3

4.2

166.3

5.3

83.2

10.7

400 Hz

99.5

1.6

49.8

3.2

124.8

4.0

62.8

8.0

500 Hz

79.6

1.3

39.8

2.5

99.8

3.2

49.9

6.4

600 Hz

66.3

1.1

33.2

2.1

83.2

2.7

41.6

5.3

700 Hz

56.9

0.9

28.4

1.8

71.3

2.3

35.6

4.6

800 Hz

49.8

0.8

24.9

1.6

62.4

2.0

31.2

4.0

900 Hz

44.2

0.7

22.1

1.4

55.4

1.8

27.7

3.6

1000 Hz

39.8

0.6

19.9

1.3

49.9

1.6

25.0

3.2

1100 Hz

36.2

0.6

18.1

1.2

45.4

1.5

22.7

2.9

1200 Hz

33.2

0.5

16.6

1.1

41.6

1.3

20.8

2.7

1300 Hz

30.6

0.5

15.3

1.0

38.4

1.2

19.2

2.5

1400 Hz

28.4

0.5

14.2

0.9

35.6

1.1

17.8

2.3

1500 Hz

26.5

0.4

13.3

0.8

33.3

1.1

16.6

2.1

1600 Hz

24.9

0.4

12.4

0.8

31.2

1.0

15.6

2.0

1700 Hz

23.4

0.4

11.7

0.7

29.4

0.9

14.7

1.9

1800 Hz

22.1

0.4

11.1

0.7

27.7

0.9

13.9

1.8

1900 Hz

21.0

0.3

10.5

0.7

26.3

0.8

13.1

1.7

2000 Hz

19.9

0.3

6.6

0.4

25.0

0.8

12.5

1.6

3000 Hz

13.3

0.2

6.6

0.4

16.6

0.5

8.3

1.1

4000 Hz

10.0

0.2

5.0

0.3

12.5

0.4

6.2

0.8

5000 Hz

8.0

0.1

4.0

0.3

10.0

0.3

5.0

0.6

6000 Hz

6.6

0.1

3.3

0.2

8.3

0.3

4.2

0.5

7000 Hz

5.7

0.1

2.8

0.2

7.1

0.2

3.6

0.5

8000 Hz

5.0

0.1

2.5

0.2

6.2

0.2

3.1

0.4

9000 Hz

4.4

0.1

2.2

0.1

5.5

0.2

2.8

0.4

10000 Hz

4.0

0.1

2.0

0.1

5.0

0.2

2.5

0.3

Crossovers for three-way speaker systems

For example, to create a simple first-order crossover for two 4-fi speakers at 4000 Hz. the value of the highpass capacitor would be 10 uF and the value of the lowpass inductor would be 0.15 mH. For a second-order crossover at

4000

Hz. the value for both capacitois would be 7 uF, and the value for both

inductors would be 0.212

lowpass

filters for

mH. The

difference

the second-order network

is

between the highpass and the that for the highpass

filter,

the

inductor should be wired in parallel, and the capacitor should be wired in series: for the

lowpass

filter,

the inductor should be wired in series, and the

capacitor should be wired in parallel. Sure, most any electronics

components could be used

in

your crossovers, but

the parts that are used in audio crossovers are strange because the values aren't standard. For capacitors, the voltages are

capacitance ratings are

The

much lower than

much

those used in

higher and the

modern

electronics.

typical capacitors used in crossovers are nonpolarized electrolytics

mylar types. The inductors

company

(also

catalogs) are peculiar

known

little

as crossover chokes in

coils of wire.

and

some

Unlike capacitors, the

crossover chokes have strange enough values that they are typically

made by

domestic audio supply companies specifically for crossover applications. Capacitors with appropriate crossover values are very difficult to find in most most inductors for crossover applications are

electronics supply houses. Also,

made by audio supply companies, is

just to

check

first

Parts Express. With a for crossovers, so

so your best bet

with an mail-order audio

company such

you know

that the

as

this,

when

component

ordering these parts supplier, such as

the parts are labeled specifically

components are appropriate.

for three-way o> Crossovers speaker systems For the sake of simplicity, the systems described in the book thus far have been for two-way speaker systems. Also, because of the extra cost, space, and work involved, you might just be better off sticking with a set of tweeters and midranges rather than throwing in woofers, or possibly a subwoofer, too. Or. even if you want to mount a subwoofer in the trunk, the higher frequencies would already be filtered out by the backseat, and one of these beasts certainly won't be

damaged by some higher-frequency

audio!

Still,

if

you are truly into auto audio, you might choose a set of separates (as opposed to three-way multiple-driver speakers) that requires a three-way crossover

(Fig.

6-14)

203

Filters

Figure

6-1

4

and crossovers

-i-o 1

1

LOWPASS

BANDPASS

|

HIGHPASS

o

//

/ l\

-6

dB

\\

1

|

-12

X /\

1

1

-18

/

1

-24 I

20

I

\/\

1

40

1

It

1

I

1/ Aw

400

100

•

\\

\

\\\\ III!

I

4K

1000

1

10K

1

20K

Hz

>

HIGHPASS (TWEETER)

BANDPASS (MIDRANGE)

INPUT

FROM

LOWPASS (WOOFER)

Crossover

AMPLIFIER

Network

THREE-WAY SPEAKER Response

rate for a three-way crossover

for the system.

The common crossover were covered

in the first

points for two-way and three-way crossover networks

paragraph of the section "Determining the speaker

crossover points" earlier in this chapter. tips for

you're

determining the crossover point

Combine in

this

information with the

a two-way speaker system and

all set.

The only

is that you have to lump both on the midrange speaker (Fig. 6-15). One

peculiarity of the three-way crossover

a highpass and a lowpass

204

and the crossover arrangement

Audiocomroi

filter

Crossovers for three-way speaker

Hf

-5

s

Figure

TWEETER

-rrrr^\

6-1

MIDRANGE

WOOFER

The three-way crossover schematic.

strange problem that you could have you're doing

is

if

Audiocom

you don't

really think

getting the values reversed. For example,

if

about what

you

set the

500 Hz and 4000 Hz, the necessary values for the highpass and lowpass filters are 80 uF, 1.28 mH, 10 U.F, and 0.16 mH.

crossover rates at

these are reversed, then none of the audio

will

If

reach the proper speakers

and everything will be cut out from the midrange. If you install a crossover network and think that you might have blown the speakers out because the audio is low and unbalanced, check your crossover values to make sure that they aren't reversed.

(J)

Mixing and matching different crossover orders There's no rule that says "You must use the same crossover networks in a system or everyone in Wisconsin will turn into slabs of Monterey Jack and the Cleveland Indians will win the World Series." Of course, you would only be able to use dissimilar crossovers in three-way or four-way separate speaker systems because the two-way systems only have one crossover. Really, there's nothing special about using different crossovers in the

A number

same

commercial crossover networks use a firstorder crossover at the lower frequency (bass/midrange) and a second-order crossover at the higher frequency (midrange/treble). This system allows the audio to be smooth and natural across the important lower frequencies, and network.

of different

still can quickly cross over the high frequencies to the tweeter from being damaged (Fig. 6-16). it

to prevent

it

205

fT'

5

and crossovers

Filters

Figure

6-16 2? Tweeter

^

A

combination crossover with a first-order lowpass filter and a second-order highpass

Z?

filter.

Woofer

^ Resistance and L pads have heard some stories about how a few do-it-yourselfers upgraded to really hot, expensive speaker systems. They were really excited about the great sound that would soon be pouring from their cars. Instead, they found that although the audio was clean, it was very shrill and highI

some

pitched. Resistors and

L pads are not part

of the crossover network, but they

can do

plenty to control the individual speakers. Also, they are simple electronics

same physical areas that the crossover networks are L pads and crossovers are often mentioned in the same resistor is an electronic component that limits the flow of a signal

that are built into the

constructed, so breath.

A

through a wire.

you are a daring, experimenting-type person, you can use resistors to reduce the volume from one particular type of speaker (e.g., the tweeters)

If

a multispeaker system. Just wire a resistor with a low value (such as 10 parallel across the terminals of the

The problem with

in

Q.) in

overpowering speaker.

wiring a resistor in parallel across the inputs of a speaker

is

change the value of the crossover point. With some work and experimentation you can tame the overpowering speakers and tune the crossover frequency, but it would probably require a large effort, which might not be worthwhile.

that the value of the resistor will

If

you decide

obstacle

3|

206

is

to

that

go ahead with the experimentation, the second major you don't really know what value will work properly. There

esistance and

is

no standardized method

is

for determining crossover values. Part of the trouble

nricU

I

determining these resistor values, like there is that speakers vary in efficiency, so unless you check the efficiency of each speaker to make sure that they match, one speaker will overpower the others. for

Matching efficiencies usually isn't a great idea anyway because chances are you would not get the best quality or the best price that you would find if you just got the best speakers that you could afford and matched them later. That is where the resistances are helpful in balancing out the system. The fixed-value resistors are very inexpensive (usually only a few cents apiece), but you will need to experiment with plugging in a number of different values so that you can pick the one that is most suitable for the system and your ears (Fig. 6-17).

that

Figure

A

first-order crossover with a resistor in parallel at the tweeter to reduce its output.

z?

^ Another possible solution might depend on the type of capacitor that you used in your crossover. Although a capacitor is obviously built to add capacitance

at a specific point in the circuit,

it

also has other values, such as

and inductance. Different types of capacitors have different ratings resistance, inductance, and the like even if their values of voltage and

resistance of

capacitance are the same.

Depending on the type of capacitors you are using, you might be able to up your problems with overly "bright" tweeters by using a different type

clear

of capacitor (one with

border on the

components,

The L pad resistors,

is

and

more inherent

likes of "snake-oil" it

might be worth a

resistance). This solution theory

try just to

might

you already have the see what happens.

remedies, but

if

it is not permanent, like soldering in the can be tuned to the proper resistance to limit the audio of the

handy because it

207

6-1 7

Filters

and crossovers

speakers.

The L pad

When

is

a

component with two separate sources

of variable

one resistance element is connected in parallel to the speaker, and the other is connected in series. When the L pad is tuned, it can reduce the output to the driver while maintaining a steady impedance. In all, the L pad is a variable resistor (potentiometer) that is able to maintain a steady impedance. resistance.

it

is

installed,

For some reason, perhaps because of the installations in door panels and rear decks, have rarely seen or heard of anyone who has used L pads in his or her I

auto audio system. The normal car stereo technique for correcting a mismatch in the

output of the speakers

equalizer. This

is

just to

tone

down

might be a workable solution, but

those frequencies with an I'd

rather correct the problem

immediately and toy around with the minor tweaking

though the audio was good enough that

I

later,

especially

if

I

felt

as

could avoid purchasing an equalizer.

Most L pads are configured to control either tweeters or midrange speakers, and some even have both types built into the same front panel. So if you want to control the speakers with an L pad. you will either need to build special speaker cabinets for the tweeters and the midrange speakers, or you will have to find a nearby position to mount the L pad and wire the speakers to the pad from their separate mounting locations.

You should never try to use an L pad in conjunction with woofers and subwoofers. The system would require massive power resistors, and the

Q of the system would be increased,

effective

which would make the sound "boomy."

Conclusion Crossovers are essential for any system with speaker separates, both to improve the audio quality and to protect the tweeters. Signal-limiting resistors

and L pads are very handy audio-balancing components, although they aren't necessary in all systems. Although a great amount of mystery and alchemy surrounds all of these components, they are all fairly simple to construct and use, so long as you keep the design simple and follow some of the recommendations, such as using the crossover-values component chart.

208

Antenna systems Now

that the radio has

been

virtually

eliminated from the auto entertainment

scene, few sound buffs even bother to consider the quality of the antenna.

For the most part, you have to be a radio hobbyist of some sort to really experiment with your vehicle's antenna system. Still, many people continue to listen to the radio in spite of its generally declining quality, and if you normally drive in a fringe radio signal area (as do), experimenting with different antenna systems might prove very worthwhile. I

(^)

A

few antenna basics

An antenna

is any object that is used to pick up radio signals. Of course, most antennas are metallic conductors of a certain length, but antennas can be made from other materials. For example, human skin isn't a very good conductor, but if you hold on to a retracted car radio antenna, the signal will improve because you have become part of the antenna. The human body works better as a giant resistor than as an antenna, so don't be tempted to bolt anyone to the hood of your car-, just use a standard whip antenna.

209

m

WWJfMM'MMMM'M'M Antenna systems

Radio theory can get very complicated, in part because it seems so intangible: however, here are a few of the basics. Every radio signal is a sine wave, and every wave that is on a different frequency has a different length. The frequency is merely the number of waves that occur during 1 second. As a result, a higher frequency yields a smaller wavelength. Knowing that light (and subsequently all radio waves) travels at 300.000.000 meters per second, you can determine the wavelength of a radio wave at any given frequency. Rather than use 300.000.000. it is much easier to calculate when the last three zeros from the divisor (frequency) are canceled out: _ 300.000 X ~ F .

where:

F

is

the frequency in

A

is

the wavelength in meters

From

this equation,

kHz

you can determine that a

AM/MW band) 555.56 of the AM/MW band), a full wavelength

bottom of the

FM

is

(VHF) broadcast band

is

much

full

wavelength

at

is

much

smaller.

The only

determining the wavelength from the previous equation

is

AM

(MW)

difference in

that

you must use

300 instead of 300,000 so that you can use the frequency 99 MHz (in the middle of the FM broadcast band), a full

the constant of

MHz:

thus, at

wavelength

The catch perform

all

at their

listening to.

in

only 3.0 meters long.

is

to

(the

reduced to 176.47 meters. The

higher in frequency than the

band, so the lengths of the waves are

540 kHz

meters long. At 1700 kHz (the top

of these equations

peak

if

and measurements

is

that antennas

they are resonant to the frequency range that you are

The resonant antenna

length as a given frequency, or division of a given frequency.

is

is

an antenna that

is

either the

same

a multiple of a given frequency, or

The most common antennas

is

a

that are less than

1.0 wavelength long are i^-wave, %-wave, and Vs-wave. A Vs-wave vertical antenna for 540 kHz would be 69.45 meters high (approximately 225')! Obviously, a 225-foot-high antenna on your car just won't cut it. So the radio designers go with a small whip antenna that is inexpensive, strong, and allows you to travel under low objects without getting the antenna stuck or ripped off. They then design the radio so that radio signals to the (MW)

AM

section are highly amplified so that the stations are strong in spite of the

210

much-too-short antenna.

and well-received

Location

Even though the car radio whip antenna is designed to receive most it won't perform nearly as well as even a '/s-wave vertical antenna. So, there is plenty of room to experiment with, if you feel so inclined. But do not experiment much with length. A too-high antenna would be dangerous and could catch on something. Not only would you blow out your head unit, but you could get killed in the process. If you want to everything well,

experiment with the antennas,

try

another route.

B- Locations Often shortwave and medium wave

listeners yearn to be away from the noise and tall buildings that obstruct the path of many of the rarer signals. A high peak or hilltop looks very inviting on those days when all that seems to come over the bands is garbled voices and ear-shattering static.

of the cities

There might be times when you really want to listen to a particular program on a radio station that you cannot receive at home. Then you might want to it. Unfortunately, given the monotonous programming that currently exists, this is doubtful; however, you are either lucky enough to have a nearby low-power college or pirate

drive to a better location to hear state of radio

be out of their signal's range), this might be the case. "Pump Up the Volume," people parked all over high school football field to listen to a pirate FM station because

broadcaster (but

still

For example,

the movie

the local "that's

if

in

where the

signals are the strongest."

Remember, when setting up mobile antennas, that the land you are setting up on is not yours (unless you live on a farm). Setting up could get you into a lot of trouble. Campgrounds and state and local land are some of the best locations for mobile antennas. Just make sure that you follow any rules and regulations that apply to this land. Some locations, such as rest stops and picnic areas around major highways, don't seem to have any set regulations; you should have no problems installing low-profile, temporary antennas on this land. A few definite no-nos would be to string an antenna across the road or to run wire about neck height across the path leading to the

bathroom. Just use

common

sense.

Private land can be another problem. These days, many people are cautious about such things as lawsuits and drug deals. Installing an antenna on someone's land, then sitting in your car for a few hours could make someone suspicious that you are up to no good. On the other hand, you could be on the land of someone who is simply paranoid. Trespassing is a good way to

211

ft;

Antenna systems

get shot or to land in

jail

for the evening (the food

even worse), so don't do

WARNING!

Extreme caution

is

If

bad and the reception

necessary to prevent electrocution

conducting antenna experiments.

overhead wires.

is

is

it!

the car

is

Do

parked

when

not perform antenna experiments near

in a

densely

perimeter beyond your parking place for power

wooded

area, search the

line poles. Carefully

examine

the precise spots where you intend to drape or anchor antennas. Ensure that the surroundings have

no overhead

wires.

Always watch the area above you.

Motor noise When

listening from a remote location in an automobile, you might decide to keep the engine running to maintain a charge on the battery or to provide heat during cold weather. Automobile engines will sometimes provide a source of receiver noise that can range from slightly bothersome to completely overbearing. The ignition systems in cars can cause a severe buzzing interference in most receivers. The only real measures to remedy the situation

are to either turn off the engine of the car, to use a diesel car (which doesn't

have spark equipment

plugs), or to wire a noise-limiting capacitor in line with (Fig. 7-1).

Another warning: Never

your

run a parked vehicle for any

length of time with the windows closed; carbon monoxide is a killer. opening a couple of windows should provide enough ventilation.

Figure

Slightly

7-1

A

212

10-A noise suppressor.

.

Simple antennas for

fly

'(jfe

AM

and shortwave hobl

Vehicle antennas Your parked car is like a portable shortwave listening station. You can obtain power from the cigarette lighter input jack on the dash, or you can use a portable battery-powered receiver.

Or you might even have DC-Ill

a car stereo that

covers the shortwave bands, such as the Philips

The

car listening trip

to catch

some

is

an interesting idea

for active radio listeners

who want

rare stations without spending a fortune, losing vacation days

from work, or neglecting friends or family for long periods of time. Even if is good for shortwave listening, you can probably find a better place somewhere else. For example. have a fair homesite for shortwave antennas, and my parents' home (which occasionally visit) is excellent for listening. Still. have had the urge to sneak out to the coast of New Jersey or Massachusetts and point a huge longwire antenna at Europe. Radio waves lose more energy when traveling over land than they do traveling over water. So if you are attempting to hear low-power shortwave or medium wave (AM broadcast band) radio stations from another continent, you are better off listening from the nearest coast to that continent. your home's location

I

I

I

(j) Simple antennas for AM and shortwave hobbyists Probably the most

common

antenna used by shortwave and

AM

(MW)

radio

hobbyists is the simple longwire antenna. This antenna is simply one long (usually 100' or longer) piece of wire that is strung in a straight, horizontal

Under most circumstances, the longwire antenna is the best AM (MW) mobile listening in a parked car or truck. All you need to do is remove the insulation from one end of the wire and attach the wire to the antenna terminal of the receiver, or wrap the wire around the end of the whip antenna on the portable receiver. Then, run the wire out the window and keep going until you reach the end and need to configuration.

choice for heavy-duty shortwave or

find a support to tie

it

to (Fig. 7-2).

Very light-gauge wire, such as #26, is excellent to use as a simple longwire antenna. Wire with such a small diameter is easy to wind, can be wound into a very small ball, and is difficult to see. Another advantage is that you can run the wire out through your car window and it will still close. Otherwise, you

would need to

pull

out the head unit and build an antenna to specifically plug

213

Antenna systems

Figure

7-2

A

random-length longwire hung

in a tree.

This little extra edge is much more important when 15°F and you would otherwise be freezing to death with a V2" window opening for the length of coaxial cable. in for this application.

it

is

Very long longwires

will

off the ends of the antenna (i.e.. the from each end of the antenna). So you should aim

be directional

signals will be received best

the wire at the direction that the signal less directional,

but are

still

is

coming from. Shorter longwires are

fine for general listening excursions.

Car antenna extender The automobile antenna can be used

to feed the signal to the shortwave

An

automobile antenna extension provides a means of lengthening the short whip that is supplied with most cars and trucks. You can lengthen receiver.

element to provide good concept behind this antenna this

quick'n'dirty longwire. This

and best of

all, it

The construction

works is

AM is

(MW) or shortwave reception

just to turn

concept

is

(Fig. 7-3).

The

your whip antenna into a

about as simple as any ideas out there,

well.

quite simple.

A

length of

major part of the antenna element. Slip the ceramic insulator, then wrap it and solder it

#16 copper

wire serves as the

end through the eye of a small at several points. Scrape all insulation from the section of wire to be soldered. Thread the other eye of the insulator with a short length of nylon clothesline rope and tie it. Fit the opposite end of the element wire with a heavy-duty alligator clip; a clip similar to that on automobile battery chargers is ideal, and it is strong enough to hold

^\

214

far

Simple antennas

for

AM

and shortwave hobbyists

Figure

—-^-Ajjil

A

„

simple car whip antenna extender.

the strain of long antenna elements. This lead should be firmly attached to the

and soldered at several different points. If you choose a smaller gauge of wire, you should be able to use a smaller size of alligator clip. alligator clip

The antenna extender

is

now

complete. With typical antenna element

lengths, the entire system can be stored in areas as small as the glove

compartment

Choose

of

most automobiles.

a likely support for the far end of the antenna element and attach

firmly. Carefully

it

extend the element wire to the automobile antenna and

make a firm connection at this point with the alligator clip. In addition to the warning about coming in contact with high-voltage lines, be certain that the entire system has been dismantled and stored before attempting to drive away from the portable operating location.

|

A

practical antenna arrangement for average listeners

The longwire antennas and antenna extensions are fun for

me

because

I

am

that are

an active shortwave

mentioned thus

listener;

however.

I

far

realize

215

7-3

Antenna systems

most auto audio

that

pulling in

some

fanatics are

much more

interested in perfect fidelity than

distant radio station through the static.

However, you can do quite a

bit to alter

the standard broadcast bands.

The

and boost the reception on both

following system could be used

in-full

of

or

in-part. haven't tried it yet, and although have seen very little information on these types of antenna systems (at least for this application), it should work well. After this book has been completed. plan to be experimenting with this system. Maybe will be able to report some helpful tips and fascinating information from these tests for the second edition of this book. Of course, if you also experiment with these (or other vehicular antenna I

I

I

I

systems),

worked

I

will

be glad to hear any information about

how

your systems

out.

The antenna arrangement

for this system is called a phased array. In a phased two vertical antennas are both fed with coaxial cable, which is connected to the receiver. Instead of having a regular, mostly unidirectional antenna reception pattern, the phased array has a somewhat directional reception pattern. Best reception is in two of the general directions, rather

array,

than

all

four.

As a

result,

it

will

receive better in directions that the array favors

and poorer in directions that are nulled by the array; would help you receive stations better. Unlike what

is

thus, this

antenna system

often portrayed in the advertisements for the miracle television

antennas, where you merely connect the junky "antenna" to the set and

become

all

of

antennas don't really perform this way. Generally there is a trade-off between directional and unidirectional performance. The more directional an antenna becomes, the less well it can receive in all directions. Directionality is generally terrible in a mobile system because as you turn on the road, the directions that the array receives best will keep turning away from the location of the radio station's transmitter. In

the signals suddenly

short,

you on

driving

will

crystal clear,

in. then null out the same station. If you are somewhere in Iowa, this might not be much of a Pennsylvania, where the roads curve more than they run

constantly pull

straight roads

problem, but here straight, this

in

system alone would be mostly useless.

Thus, you might need to correct these problems. One easy solution is to wire a three-way switch into the dashboard, near the head unit. In the one

one antenna would be connected to the antenna. In the center would be connected together and form the phased array. In the last position, the other antenna would be connected to the head unit. With this switch configuration, you would be able to use the phased position, only

position, both antennas

216

whenever a weak

is coming from a direction that is within the you then drove around a curve and the reception deteriorated, you could switch to one of the other antennas to improve the reception (Fig. 7-4).

array

station

"hot" direction of the array.

If

Figure

Front

antenna

Head

unit

x

Front antenna

-

Both antennas Rear antenna

s

Rear antenna

Antenna switch

An antenna

Some

array.

have about this system deal with the impedances, and the distance between the antennas. The antennas are typically arranged in a manner so that they are spaced a particular distance apart, depending on the wavelength of the antennas, the impedances, and the like. Under normal circumstances, if the antennas are placed closer or farther apart than the predetermined spacing, the antenna receiving pattern will be skewed (e.g., the pattern will be less directional than of the questions that

transmission

were aligned properly).

if it

No

I

lines,

equations for determining the spacing distance are included here because is so short and will vary depending upon each antenna's design.

the distance

locations for your antennas ultimately will be based more on where you can attach them to the car than on mathematics. As a result, you will determine the most functional system by experimenting with different antenna locations until you find a spacing that yields the best-possible

The

reception.

217

7-4

Antenna systems

Space-diversity reception

What would be

great

is if

you could

build

an electronic gizmo to automatically

switch between the different antenna configurations so that you wouldn't

have to spend more time with your hands on the switch than on the steering will be a bit different. This section lightly covers space-diversity reception, which is an arrangement where an electronic device receives signals from two or more different antenna sources and chooses the strongest signal for inputting to the receiver. wheel. Well, you can, but the system

Rather than choosing between single antennas and the directional array, the

box chooses only between the two single antennas. suppose you could make it choose between two antennas that are in a directional array and another separate antenna; then the system would choose between the directional array signal and the unidirectional single-antenna signal. On the downside, you would be stuck with having three antennas perched on your car. space-diversity

I

that

up the coupling boxes for space-diversity know of any company that sells them; however, if you have an interest in electronics, then you might want to build a space-diversity coupling box from a kit. This project was featured in a recent issue of Radio-Electronics, Popular Electronics, or Electronics Now! The project was somewhat complicated, but overall it seemed like something that someone with limited kit experience could build without many difficulties. If you are really determined, you can build the project from the schematic and etch your own PC board, but would feel much more comfortable building Unfortunately, you can't just pick

systems anywhere.

In fact,

I

don't

I

from a

tt)

kit.

Conclusion Although various antenna systems are not of primary interest to the thunder boomers and audiophiles in the auto audio world, they are practical radio reception performance boosters. And they are a blast to play with if you enjoy scientific experimentation.

218

Wire, cabling, connectors, and transmission

systems The most forgotten part of any audio system is what actually transmits the power and audio signal from one part of your car to another. Wire and cabling are often forgotten because they are about as boring as a Paul Anka record. Why would you waste your time and money working on wires when you could purchase and spend your time with a really cool head unit? have no idea. would much rather play with all of the buttons and displays on the head unit! In fact, while upgrading to the systems that are mentioned in this book, forgot all about the wire and cabling several times. The other stuff was just so much more fun and interesting. I

I

I

219

Wire, cabling, connectors, and transmission systems

When you

down

get right

to

it,

the subject of wire and cabling

is

very

important. With a bad choice of wire, you could decrease the quality of the

sound, pick up interference, or even start a car

fire;

however, the dangers of

poor wire choice are an extreme exaggeration. As long as you follow the manufacturer's specifications for the gauge of the wire that handles the power to and the audio from any particular piece of equipment, your system should be safe. After that point, the only difference will be in efficiency and overall sound quality.

Should

purchase high-end audio cables?

The

I

science of cabling audio

topics of auto audio (and

is

quite esoteric,

home

and

it is

one

of the

most argued

audio, for that matter). Claims about the

cabling run from being an audio cure-all to being an absurd case of snake-oil advertising.

but

I

I

won't

tell

you to spend a large sum of money on high-end

won't say that these cables

The problem

is

that

when

will

not help in

some

cables,

specific applications.

the cables use precious metals, for example, they

And if you can't afford a thousand dollars why would you blow several thousand on the audio and power cables? However, many of the high-quality commercial cable companies (Scosche, AudioQuest. StreetWires. and Straight Wires) make cable that is much less expensive. These companies all sell cabling that runs from the very high-end to that which is affordable for anyone who can purchase a new auto audio system. are

bound

for

your stereo system,

to be hugely expensive.

Like everything with high-end audio,

if it is important for you to have the and you have the money, then buy it; otherwise, if the different grades of audio cables are a concern to you, then do some comparison shopping. Check the cables in different systems if you have a chance, or talk to salesmen at different local stereo installation shops and see if you can do some comparative listening. If you are lucky, you might be able to test the same system using different audio cables. Of course, beware of some of the sales tricks, such as turning the volume up higher on the one head unit so that the system will "sound better." If you have friends who have trustworthy opinions on car audio, then you should talk to them if you can't find any

best

"reference" audio cabling.

220

After these tests, choose the cabling that sounds the best for the lowest price. Even if you can notice a difference, the better cabling might not be worth any extra cost. If you are running cables in a competition vehicle or want a car that is impressively meticulous, then you might want to purchase

cables that look as

good or

better than they sound.

Some

of the wires that

are protected with clear insulation are excellent for this purpose.

1) Wire Other than one peculiar exception (using an FM transmitter to feed the audio signal from a CD changer to the head unit), wire is always used to transfer audio and electricity between the various components. Few people think about the different qualities of wire and the efficiency as a signal travels from one component to another. However, wire is made from several different materials (of many different qualities) using different drawing methods. Also, cable can be made with either one single wire, with many strands, or with bundles of strands: it can be shielded to prevent other signals from causing interference; and multiple wires can be encased within either a round or a flat

cable (Fig. 8-1).

Figure

A number

of different types of speaker, interconnect, and power cables.

221

8-1

'jmrjmrm

Wjm

Wire, cabling, connectors, and transmission systems

Most audio and power cables are made from copper. But if you use wire that was intended for some other electrical application, it might be made from another element or elemental combination, such as aluminum or coppercoated steel. Generally, copper is the only element to use to transmit audio and power signals through your car. Aluminum is fine for use in electric fences or in lengthy radio antennas where low cost is more important than high efficiency. is an excellent conductor of electricity, several other elements, and gold, conduct better; however, their costs are obviously prohibitive for most electrical applications. Silver is occasionally used,

While copper such as

silver

though, for very high-end wiring applications; gold

is

commonly

plated over

wiring connectors (such as the audio inputs to amplifiers, speakers,

J)

etc.).

Wire shapes and styles A number

of problems can occur

together via wire. effect

is

when

Two major problems

different

components are connected

are resistance and skin effect. Skin

the scientific property by which electricity travels on the outside (the

"skin") of a

conductor

(Fig. 8-2).

It

has nothing to do with rashes, blushing,

acne, leprosy, or a host of other dermatological problems. Skin effect causes different

Figure

problems

in different applications.

8-2

A

visual representation of skin effect.

when transmitting at radio much power into a conductor that is

©Audioauest

For example,

frequencies,

too

too small

if

a station

is

outputting

conductor that has too little surface area per watt of power), the resulting heat could cause the radio antenna to burn up. At audio frequencies, skin effect is a completely different monster. Instead of the "bigger

222

is

better"

maxim

(a

that rules for radio

Wire

conductors, larger diameter wires can cause other problems that result in high-frequency distortion. This distortion problem occurs in both solid and multistrand conductors.

how

Resistance

is

another problem that plagues

resistance

is

the opposition to an electrical signal flow. Although the

electrical circuits. Recall

resistance through a wire will cause a slight decrease in the signal strength,

Solid (single-strand) wire has a

You can see is

that

diameter

is

much

higher resistance than stranded wire.

problems occur with

too large, the signals

yet. the

it

cause some distortion.

will also

will distort

this type.

If

the diameter of solid wire

as a result of skin effect. Yet.

too small, the resistance of the wire

will

if

the

cause distortion. Worse

two boundaries overlap, and you can be stuck with some form no matter what the wire gauge is.

of

distortion

Now

that your

dreams of using solid-conductor house wiring

audio system have been dashed, stranded wires. of zip cord,

The

it's

your auto

something along the line conductors of stranded twisted hookup wire, the two independent zip cord

typical speaker wire

is

which consists of two insulated

wire. Unlike parallel

for

time to review the different types of

wires are connected along a

seam

usually

parallel

that runs the length of the wire.

in speaker cables, some companies dilemma by gradually turning the wires throughout the length of the cable (Fig. 8-3). By doing so. wires that are in the center at one point are later shifted to the outside, where most of the current is being

Returning to the problem of skin effect try to

reduce

this

transmitted. This technique greatly reduces the negative results of skin effect.

Figure

Separate wire strands running throughout a cable length shift position.

223

8-3

Wire, cabling, connectors, and transmission system

To

further eliminate the negative effects,

sometimes either stranded bundles

or solid wires are gradually turned around an insulating core.

As

a result,

each of the wire strands within the bundles or surfaces of the single stand wires

is

being slowly turned, so the antiskin effect

is

doubled. Sometimes

these solid wires or bundles are insulated and kept a certain distance apart to

prevent them from interacting

Figure

(Fig. 8-4).

8-4

Round

Hyperlitz conductor

Hyperlitz cable

Insulated wire bundles.

Hybrid technology:

crystal

©Aud,oouesi

Another type

of audio cable uses several parallel solid conductors or stranded

wire bundles.

The purpose

bundled wires described

is

much

in the last

the

same

paragraph

as the theory behind the (Fig. 8-5).

of wire, the parallel multiconductor ribbons are

types, spacing distances,

Figure

hyperlitz: indigo

made

Like the other types

with a variety of wire

and jacket and insulating materials.

8-5

Parallel flat cable. ©Audioes

Flat hyperlitz:

224

F-18 and F-88

The

last

general category of audio wire

is

that of shielded cable. Shielded

any cable that shields the wires inside and prevents various types of electrical interference from entering the lines. Shielded cable is especially important if the car's electrical system is noisy or if the speaker cables will be cable

is

running parallel to power cables. Likewise, some power cabling

is

also

shielded to prevent electrical impulses from emanating out from the cables.

One

most

common

forms of shielded cable is coaxial cable, which is surrounded by an insulating dielectric material, then a layer of braided copper wire shielding wraps around the dielectric (it makes a sort of cylindrical-copper plaid pattern), and it is covered with an outer insulating jacket (Fig. 8-6). One of the most visible applications of standard coaxial cable is for cable television. Coaxial cable is always used to route the television signals from the source to the home (at least in all of of the

consists of a center conductor that

A number

the television cable runs that I've seen).

of different types of coaxial

cable have also been designed for audio-specific purposes (Fig. 8-7).

Figure

Outer insulating sheath

Inner conductor

Shielding (copper braid and/or

foil)

Insulating dielectric

Shielding

(copper braid

in this case)

_.,

Inner

conductor Insulating dielectric

Outer insulating sheath

A breakdown So which

of coaxial cable, showing

cable

is

its

parts.

best for listening in the car? In general, the

aforementioned cables are all of much better quality than what you would typically find packed with new speakers or at a local electronics store. Most of the specialty cable companies (Scosche, AudioQuest, StreetWires,

225

8-6

Wire, cabling, connectors, and transmission systems

Figure

8-7

Patented hyperlitz: conductors include

Symmetrical coax: turquoise and topaz

air as

primary insulation

Ruby, quartz, emerald and

lapis

Several different types of coaxial cable that are intended for audio purposes. 6

A idioOuesl

Straight Wire, etc.) specifically produce their cabling for audiophiles, so their

products won't be low grade.

The

differences

between the specialty cables

probably won't be important to anyone except audiophiles.

§1

FM

transmitters for compact disc players The one

peculiar exception to using wire for routing signals from

location to another

is

in the

one

case of compact disc players. Because of the

compact disc head units, it is common compact disc player in the car. This method is cost of

for

people to use a portable

relatively inexpensive,

and the

player can be used various places outside of the car.

The

portable

CD

player

is

normally connected to a cassette head unit via a

wire and an audio adapter that resembles a cassette (Fig. 8-8).

adapter loads into the cassette player,

just as a

The

cassette

standard cassette would.

The

audio from the portable compact disc player then travels through the wire,

and through the heads of the cassette player. The about $20 to $30, so they really are a costmeans of bringing digital sound into your car.

into the cassette adapter,

adapters normally effective

226

sell

for

m

FM

transmitters for

compact disc play

Figure

A compact

disc

changer with a matching

FM

transmitter.

Denon

However, the loose wires do bother some people, and if you don't have a mount for the portable compact disc player, there is a chance that it could get kicked, stepped on. or thrown forward during a sudden stop. As a result, some people would rather connect their portable to a small FM stereo transmitter. After the connection is complete, you tune the transmitter to operate on a clear frequency. Then you turn on the car's FM stereo radio and tune to that clear frequency on the FM (VHF) band. This method is especially handy for anyone who wants to listen to compact discs in a rental car without tearing into the car's wiring. this arrangement is cost. Mono FM transmitters are perhaps as little as $10 for a kit; however, most stereo kits cost at least three times more than that and the enclosures for the circuit boards will add another $10 or $20 onto the price tag. That price isn't so bad. except that most of the lower-priced kits have some stability and audio problems that must be corrected to boost the signals up to FM (VHF) stereo broadcast quality. For example, replacing the original capacitors with better

The worst problem with quite inexpensive,

capacitors (such as those

made

with tantalum or silver mica)

will

often

improve the performance considerably. FM stereo transmitters thai are free of these problems and have great audio usually run about $100 to $150.

227

/£

8-8

Wire, cabling, connectors, and transmission systemss

Radio Shack has a $39.95 FM-stereo transmitter that can make this arrangement much more cost-effective. Before the Radio Shack transmitter

came on

FM

the market.

I

said that for the price of the standard,

more expensive

upgrade to a compact disc head unit instead. But this low-priced transmitter seems like the way to go if it produces high-quality audio. At this writing, no results of testing this equipment had been published, but it is certainly worth checking out. transmitters,

you might as well

Different manufacturers

do

just

offer small

FM

transmitters (what they

call

FM

modulators) along with their compact disc changers. These units are usually found only in the higher-priced changers: however, Sound Barrier does offer the CD-10FMC 10-disc changer for a list price of $399. which is considerably less than the other models with FM transmitters.

You are probably

better off either hardwiring the

waiting until a changer with a matching

FM

changer to a head

transmitter goes

on

unit or

sale at

clearance prices.

Making connections Making good connections is quite important if you want your system to sound as clean as possible. High-end audio connections are made in a bit different manner than for nearly any other electronics application: the wires are either "tied off" together or soldered and possibly weatherproof ed. Some solder and a few wire nuts would be all that you would need to install the wiring on an electrical system of some sort. This

is

some

a far cry from connections in the audio world.

If

you want

to see

looks of terror and/or absolute disgust, talk to a professional installer

how you connected your system of audiophile-brand and a/d/s-brand speakers and Rockford Fosgate amplifiers using only 18 wire nuts! That's almost on par with ordering caviar from an exclusive French restaurant and about

dousing

it

with cheap ketchup.

The standard method of connecting audio and power cables together is to crimp them into terminal blocks or plug-in assemblies. The terminal block is a plastic block with an even number of little open cylinders running through it (Fig. 8-9). Two screws run into the top side of each little cylinder. Once you find the two wires that you want to connect, you place the end of each one into the opposite ends of one of the cylinders, then you screw the screws

228

down from

above, and (as a

result)

crimp the wires together. Speaker

Making connection

Figure

Connecting wires together

in

terminal blocks,

auoisoousa

and power terminal blocks are normally different; power terminal blocks are very heavy-duty units that often have thick "windows" (so that you can see inside), plus large screws, solid cylinders, and the like to handle the amps. Speaker terminal blocks are much smaller and less stout because they don't need to be any tougher. that is even neater than using terminal blocks is to use wiring harness plugs. These plugs are similar to those that are often used in the backs of head units to input the power cables and to output the line and

One method

speaker audio levels. Although they are often only used at the head unit, these plugs can be used in other locations, such as at each of the speakers, to form a sort of "quick disconnect" speaker arrangement. The problem with these plugs is that although they are easy to plug and unplug, they are difficult to remove for rearranging wires. This isn't normally a problem, but it is if

you

like to

experiment with your system and frequently need to

rearrange the wires.

229

8-9

Wire, cabling, connectors, and transmission systems

Another method is to skip the terminal blocks altogether, put a piece of heatshrink tubing on the wire, and crimp the wires together using a crimping tool or a multipurpose wire stripper. Then solder the wires together and slide the tube in place over the connection. If the wires weren't hot enough to shrink the tubing, heat

Remember

it

until

it

shrinks tight against the wires.

that solder should only be intended as an electrical connection,

not a mechanical connection. Although solder

will

strengthen any

joint,

it

does not handle physical stress very well. Some audiophiles will say that solder is not much of an electrical connection either. In my opinion, that's a mostly bogus argument. The antisolder folks claim that because solder is a mixture of lead and tin (neither of which conduct electricity nearly as well as copper), the signal loss and distortion installer

took

his or

soldering, then the wires other.

The

electrically

would

still

be severe at these

joints.

If

the

be making very close contact with each

solder would then serve to

and

will

her time and solidly crimped the wires together before

physically),

and

it

make

the joint a bit stronger (both

would also help to waterproof the

joint.

Wire nuts are a poor method to connect the wires together because the joints are not especially reliable. A few years of road vibrations will cause these connections to become even less reliable. It would be terrible to hit a pothole and have one or more wire nuts pop loose and short out. Depending on what wires shorted, you could damage or destroy your head unit, speakers. amplifier(s). or

My

favorite

power system.

method

for connecting wires

is

to use terminal blocks

because

everything can be connected simply and easily, the blocks are usually only a

couple of dollars apiece, and the disconnection process is very easy. To make the wire runs even neater (such as in locations where the wires will be visible), screw the terminal blocks onto a hard, flat surface, and secure the wires so they won't get pulled out of place.

Soldering problems and dangers isn't difficult, but it seems as though many people with interests in auto audio have never soldered before. To make a solder joint, have the connection (wires, terminals, etc.) in the final connection position that you

Soldering

want them to be

in. Then preheat the soldering iron until it reaches a very hot temperature and can melt solder easily. (If you try to solder while the iron

warming up, there is a much better chance that you will make a cold you will overheat the wires and melt the insulation.) Next, heat the joint from underneath and place the tip of the solder against the joint from above. The solder will flow into the connection (Fig. 8-10). is still

solder joint or that

230

Figure

wire

Making a solder

joint.

Some

people try to solder by melting the solder against the tip of the iron, is always attracted to the heat, so the solder will stick to the iron, and it won't flow into the joint. This method will almost surely produce a cold solder joint. but solder

The is

last

two paragraphs covered the problems

the danger.

component speaker

problem will

line, fill

line if

Be very

that

is

careful

when

in the circuit.

while the speaker

you are soldering

related to soldering;

now

here

soldering that you don't overheat a

For example, never solder a connection connected. It probably won't be a

a

in

is still

at the

dissipate along the way, but

if

other end of the wire because the heat you are anywhere near the end of that

you could quickly zap out the speaker. If your refrigerator already has you now have a handy cassette eraser!

its

of powerful magnets,

This soldering situation can also be dangerous to parts other than speakers.

Heat is especially damaging to transistors and integrated circuits, but chances are that you won't be soldering around those parts anyway; however, you could basically end up doing this if you solder the wires in a wiring harness while it is attached to the head unit. The heat will conduct through the wires and into the power inputs or the speaker outputs, and you could severely damage the head unit.

231

8-10

ire,

3|

cabling, connectors, and transmission systems

Planning and assembling the system Recall from earlier in this chapter that audio system wiring

is

one

of the

most

forgotten aspects of an installation. In terms of being overlooked, wire rates

with the spider in a speaker. Likewise, as people are thinking about whether or not the head unit

handsome

in

the dashboard, deciding

how

to

mount

will

look

the amplifier in a

convenient location, or determining whether the holes

in

the speaker plates

match the factory mounting locations, the wiring goes unnoticed. But when the need to rewire occurs, then it's time to scratch your head and wonder why you didn't think about this earlier. will

Before you

start

working on the wiring

in

an auto audio system, be sure to

disconnect the negative terminal of the battery. There's no reason to play

dangerous with yourself, the components computer system.

in

it

your system, and a car's

Everyone knows that car wiring runs throughout the dashboard; however, the wiring also runs from the front to the back for the radio's rear speakers, taillights

and turn

this wiring

is

signals, fuel

gauge, and the

often quickly forgotten.

like.

The standard

Because

it is

out of sight,

cable routes are either

along the bottom side of the transmission or along the edges of the doors in the corner where the floor panels reach the doorframes (Fig. 8-11).

Figure

8-

I

A

bundle of wires routed underneath the carpeting.

232

lanning and assembling the syste

Replacing the speaker wiring or running the wiring for a

new

dedicated

amplifier can be a major task. Before

you start to install the system, you should determine what type of cable you will be using and how much you should purchase. To find the lengths, determine where the speakers. amplifier(s). head unit, equalizer, compact disc changer, and any other components will be laid out. Then use lengths of string or wire to find the exact lengths. Be sure to account for any extra bends or corners that the

wire

will

be making.

Allow an extra 6" to 1" (15.24 cm to 30.48 cm) for every long cable run and about an extra 3" to 6" (7.62 cm to 15.24 cm) to be safe. It might seem like a lot of extra work just to measure the wires, but when you deal with custom wiring, that extra foot or two here and there could add up to quite a bit of

Note any

RCA

money.

specific connectors that

plugs

(Fig.

you might need, such as terminal blocks,

8-12). slide-on speaker clips, and the like (Fig. 8-13).

Figure

StreetWires cables with specialty RCA plugs at the etlds.

When you

SireeiWxes by Esotanc Audre

USA

plan out the wiring for your vehicle, try to either run the audio power cables on opposite sides of the car or use shielded

cables and the

cables to prevent noise from entering the audio cables (Fig. 8-14). Even

if

you can't place the power and the audio cables on opposite sides, at least try to space them a few inches apart. This distance alone will decrease the noise pickup, compared to having the wires bundled together. Before you start running the wires, make sure that you have made any solder joints that are

233

8-12

jvarjv^i Wire, cabling, connectors, and transmission systems

Figure

8-13

The "Blueprint for Sound" car diagram so that you can plan your system's wiring with much more ease and exactness. StreeiWires by Esoteric Audio

234

USA

lanning and assembling the syste

Figure

BLUEPRINT FOR SOUND

STREEIWIRES

VEHICLE INFORMATION

POWER SYSTEM INFORMATION WIRE RED

BLACK

HEAD UNIT

10ga_

10ga_

8ga_

8ga_

4 go

4ga

FRONT

2 go 1/0 go_

2ga_

REAR

1/0

EQ/CROSSOVER

AMP AMP SUB AMP

go_

CONNECTORS 10

go

8

go

ALTERNATOR. CAPACITORS. 4 ga

l/0gq_

2go

distribution block

|

fuse/distribution

?

ring terminals

S | S S

batter/ terminals

bamer spades fusing

INSTALLATION

COMMENTS

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Continued.

235

8-13

Wire, cabling, connectors, and transmission systems

Figure

8-14

Runs of audio and power cables

that are

sides of the car to reduce noise pickup,

necessary; the exception

make

is if

on opposite

scosche

you have a 12-V soldering

iron

and plan

to

the solder connections while you are in the car installing the wiring.

After you have run these wires, tape

tape in the areas that

will

them

in place

with a few pieces of duct

be under the carpeting.

Power cables and fuses Wiring

is

a relatively boring subject and

power wiring

is

the most boring

aspect of this topic. Power wires and fuses don't do anything and although

you might notice a difference in audio quality between using light-duty and heavy-duty cables, chances are that you won't. But you will notice the difference with fuses

if

overvoltage condition

236

there

(Fig.

is

a problem, such as a line spike or a general

8-15).

wer cables and fuses

Figure

The heavy-duty

cables, screws,

fuses, etc. that are supplied with

the Rockford Fosgate Punch 200ix amplifer.

ea

•

With wiring gauges, the problem

is just as great, if not even greater. If you recommendations for correct wire gauges (particularly in the case of high-powered systems), you could overheat the wires and start a car fire. Always play it safe and stick to the recommended wire gauge. Likewise, be sure to use heavy-duty power terminal blocks and power splitters on the initial power wires; otherwise, these blocks could overheat and melt, which would create the possibilities for either a fire or a short-circuit that would be dangerous to the audio system.

fail

to follow the manufacturer's

Many

on the market are primarily for deafening amount of decibels. This book isn't aimed at competitors or at people whose main goal is to vibrate all windows within 150 yards (137.16 m). As a result, this material is succinct. of the power-connecting devices

competition vehicles that output a

literally

The foundation of a super-powered system is the alternator. Without a huge amount of current, you can't have a huge audio signal. Several companies offer

high-power replacement alternators. Scosche even offers optional gold on some of its alternators. That would surely be one of the only cases

plating

where a

would pass by the car stereo

thief

Quite often people larger battery.

with

A

more ease

operating time

try to

the car

is

but allow the car to be started

is

turned

off.

Massive batteries seem to be big

audio companies. This feature

competitors

Another hot item

do nothing

wintertime and produce a few extra minutes of stereo

in the

sellers via the specialty

for car audio

boost the power to the audio system by installing a

larger battery will

when

to steal the alternator!

is

especially important

(Fig. 8-16).

The more power can

the brass- or gold-plated battery terminal post.

theory behind these items:

The

better the connection, the

237

8-15

jay j«r

gp £&f& ttf ^FMf ^? ^pJf ^PMP MW ^f MP JffJ&Jf £0Jf Miff J&JtfJB

Wire, cabling, connectors, and transmission systems

Figure

8-16

A

heavy-duty competition gel cell battery that can output 50 for 50 minutes. SlreetWires by Esoteric Audio USA

amps

is true, but it won't make a you are pushing your car's power system to its limits. If you are pushing the system to that point, you should probably either buy a new, higher-powered alternator or turn back the volume to give your ears and

reach the head unit and the amplifiers. This

difference unless

your neighbors a break.

Grounds The ease

of grounding

pin a

on a

an auto audio system is often on par with trying to The process of debugging ground noise problems is so complicated that Scosche's Autosound Encyclopedia dedicates more than 60 pages to grounds and noise problems! The ground is the point in a circuit tail

cat.

connected to the Earth It is impossible for an auto audio system to be connected to a true ground (the Earth) unless you listened to music in an immobile car. So the car requires an artificial ground. Because a car consists of a large mass of steel, the chassis or frame can be successfully used as an artificial ground. that

is

used as a zero-voltage reference and which

or to a circuit that

238

is filling

in as

is

a substitute for Earth.

order to complete a sufficient electronic ground, the ground wire must be

In

electrically

and physically connected

to the ground. This

means

that although

the ground wire must be physically against the chassis, the chassis steel must

be clean and bare. Any surface dirt. dust, or grease will insulate the wire from the chassis, and it will, at the least, cause audio problems (noise, hums, alternator whine, etc.).

To

install

loosen

it.

a ground, find

Then scrape

one

of the

ground

bolts (behind the dashboard)

and

the metal edge around the screw with a pocket knife

Then connect the ground and tighten the bolt or nut. To prevent the connection from taking in some water and rusting, lightly cover it with caulking or silicone grease. At that point, you should have no ground problems unless you add more

or better yet use a metal brush to shine the steel. wire,

components

to the system.

you can't find a conveniently located ground terminal, don't add more wire and hunt for another already-established terminal. Long ground wires are generally ineffective even if the ground connection is good. Instead, drill a hole in a solid piece of steel in the car. add a screw or bolt, and follow the procedure outlined earlier in this paragraph. Be extremely careful and make sure that the spot you plan to drill is free of any wires and other auto components, and be sure that it is in a structurally sound area. If

the ground is sufficient, everything will work properly, and you shouldn't have any major problems with noise or interference in the audio. That's fine and dandy, but what happens when the system doesn't work? One of the complications of ground systems in a car is having a number of components connected to the same ground. When this happens, the chances of getting ground loops are multiplied. Ground loops are differences in the ground reference voltage between two (or more) different components in the same system. Ground loops often result in hums on the audio (Fig. 8-17) If

One

connect if

problem is the "star ground." which means same ground point (Fig. 8-18). This is a fine system compact disc changer in the trunk or an amplifier (or

solution to the ground-loop

everything to the

you don't have a

several) in the trunk or

under the

seats.

It

isn't feasible for

the large systems.

Grounds will always be a complicated matter, and they vary from car to car. sometimes even between cars of the same make. You can "sniff out" ground loops and noise problems with electronic test equipment, but that is an extensive process that is way beyond the scope of this book (Fig. 8-19). My advice for grounding problems is to try grounds at different positions and experiment with noise-limiting capacitors. If you are an installer, try checking

239

I

Wire, cabling, connectors, and transmission systems

Figure

8-17

Trunk

+ 12V

Firewall

1

1

Head

i

+ 12V

+12 V

...A

* *

unit

lo:.::::::ld

Amplifier

—J

L^l\\ L0—

/77 Body ground

Body ground

/77 Body ground

Voltage drop Resistance

caused by

between 2 points

current flowing

through resistance

The anatomy of a ground

Figure

8-18

loop.

Audiocomroi

= 1 1 : i : i e i

o o

ii

:i:i:i:ii:

^L A

star ground, where ground. AudioControi

out the Scosche

all

audio components are connected to the same

Autosound Encyclopedia. The high

of dollars) will prevent

price (into the hundreds any layperson from purchasing the reference, but it is

an invaluable resource for the professional or shadetree

>3l

240

installer.

Conclusion Wire, cabling, connectors, and transmission systems are not the most interesting aspects of audio systems, but they certainly are important.

require

some

extra

work

to estimate lengths, plan,

and

install,

so

it

They

is

important to take your time and think about the arrangement. Grounds are not as

difficult to

plan out. but they are often

Fix-it jobs, therefore,

much more

contrary to

install.

are often quite complicated.

241

WMWMWMWMPMWJMFM¥MWMWMPMWMPMWMPMPMPMPMPMPJMM§ Wire, cabling, connectors, and transmission systems

Figure

8-19

In

Symptoms

sound system when engine

is

Variable with engine speed

running

Variable with engine speed

Wiring

Possible

entry points

Power, ground and memory

or patch cords

Ignition

Ignition

Ignition

components

components

components

(coil, distri-

(coil, distri-

(coil, distri-

butor wires,

butor wires,

butor wires,

accessory

plugs)

plugs)

plugs)

radiation

components, bad antenna

Routing or

Routing or broken cable

ground, or

ground loop

ground braid

Antenna

Speaker leads

Direct

Antenna

chassis

I

Possible

Worn

Ignition

1

or electric Alternator

or

defective

Possible faults

Defective

ignition

alternator

Vehicle harness

bad antenna ground or

routing

routing

routing

antenna ground or

Eliminate

reroute

ground loop

Fix

Reroute problem lead

antenna cable

Fix antenna

ground or

Reroute I

vehicle

reroute

harness away

antenna cable

from unit

Repair or replace bad

Shield unit

alternator

MU-metal

Add hood ground; Possible solutions

Add

ground exhaust pipe (rear antenna)

to

filter

power and

memory

leads

Repair or suppress

Repair or suppress

ignition

ignition

components

components

Use shielded coax cable for speaker lead

Replace bad patch cords

using

Troubleshooting charts for eliminating noise in the sound system (A) with the engine running and (B) with or without the engine running. Sanyo

242

Conclusion

Figure

B

sound system with or without engine running

In

1

Constant regular or bua

Single snap with

thrown switch L

static

Humming or hissing

Symptoms

I

Wiring 1

Possible

1

Direct thru

Antenna

chassis

Power, memory Speaker leads patchcords ground

Wiring

entry points

Ignition or

Accessory

Accessory

Accessory

accessory

switch

switch

switch

radiation

or motor

or motor

or motor

electric

(

Improper grounding

Possible

source

,

Vehicle harness routing

Improper antenna ground or

Routing or Routing or ground loop

broken coax ground braid

Ground loop

Possible faults

cable routing

Continued.

243

8-19

Shortwave radio

in

the car North America, few people know exactly what shortwave radio is. It seems every time that my parents or friends mention to someone that one of my hobbies is shortwave, am invariably faced with the question "So, do you talk to people across the ocean?" When reply with "No, those are ham radio operators. just listen to broadcast stations," it seems to suck In

like

I

I

I

everything out of what they had to say to me. usually either leave almost immediately after about 30 bewildered seconds or say "So, you have never talked to anyone on your shortwave radio?" understand that it's a peculiar and misunderstood hobby, so I don't say "No, do you talk to people on your television set?!" After my usually polite "No, it's just a receiver, not a transmitter," they then leave. Needless to say, people don't stand in line to talk to me at reunions. I guess it beats them knowing about my interests in car audio and having everyone blame me for blaring my stereo and waking them up at 3:30 a.m.

They

I

rrv

244

Shortwave radio

The shortwave which

is

radio spectrum

fills

the space from

1600 kHz

to

in

the car

30 MHz,

a rather large chunk of space. Rather than merely consist of one

band, the shortwave frequencies are a patchwork

quilt of different

radio bands

The two best-known services on shortwave are the citizen's band (CB) and the numerous amateur (ham) radio bands: otherwise, there are numerous broadcast bands and sections that are dedicated to various utilities. The CB and amateur bands consist of hobby two-way communications. (Table 9-1).

Local and International

Broadcast Bands

AM/MW band

540-1700 kHz

2300-2495 kHz

120-m band

3200-3400 kHz 3900-4000 kHz

90-m band

4750-5060 kHz

60-m band

5900-6200 kHz

49-m band

75-m band

7100-7350 kHz

41-m band

9400-9990 kHz

31-m band

11600-12100 kHz

25-m band

13570-13870 kHz

22-m band

15100-15800 kHz

19-m band

17480-17900 kHz

16-m band

18900-19020 kHz

15-m band

21450-21750 kHz

13-m band

25600-26100 kHz

11-m band

88000-108000 kHz

FM/VHF band

The broadcast bands

are

all filled

with a variety of private and governmental

stations that broadcast music, news, radio plays

events, and propaganda. Utilities

Table

is

and dramas, comedy, sports

a generic term for a very wide subject,

communications between ships, teletype of most any sort (including from news bureaus), weather faxes, military communications, and even coded number pads from "spy" stations. typically

"wires"

Because of the poor quality of the audio for two-way communications and also because of the subject matter, the most popular in-car listening would be focused on the broadcast stations (after all, few people will have weather fax decoders

built into their cars).

245

9-1

Shortwave radio

in

Rather frequently someone asking questions.

up

One

the car

will

of the

my shortwave car stereo and start common is "You mean that radio can pick

hear about

most

from around the world?"

stations

I

usually tune in the

BBC

(British

Broadcasting Corporation) or maybe Deutsche Welle (The Voice of Germany)

and let the person listen a little. The next question is usually "You mean coming from England?!" (or Germany, depending on which one I tuned Although most of the people

who work

this is in).

with shortwave on a regular basis

for granted, the distances covered by

shortwave radio stations are

take

it

truly

amazing.

well.

Even small, portable ham stations, minipowered private broadcasters, and clandestines can be heard around the world.

And

it's

not just the huge government stations that get out this

pirates,

The methods by which shortwave a

bit different

than those

are familiar with these methods.

read a

you

radio signals travel from the transmitter are

standard broadcast bands.

in the

As a

result, it's

And few people

important to

at least

have

about shortwave propagation, broadcasting, and listening before listening on your own. It saves a few headaches.

little

start

Propagation might be best to start with the basic characteristics of shortwave reception. Shortwave reception is an unpredictable, very complicated beast. The unpredictability is certainly one of the factors that attracted me. It's exciting when you get a chance to hear stations that normally aren't audible in your It

region of the world.

Long-distance radio reception is possible thanks to one layer of our atmosphere known as the ionosphere (Fig. 9-1). The ionosphere is many miles above the Earth, where the air is "thin" (containing few molecules). The ionosphere is bombarded by x-rays, ultraviolet rays, and other forms of high-frequency radiation from the sun. This bombardment ionizes the layer by stripping electrons from the atoms in the ionosphere. The ionized layers of the atmosphere make long-distance radio communications possible.

The ionosphere can

also be divided into several layers, but the D, E,

layers affect radio propagation.

the Earth.

The

The D

layer

movement

of the sun in the sky.

gradually grows in strength in the morning, gradually decreases until

it

generally stronger in the

summer than

246

disappears by in

is

and F

the closest to the surface of

existence and strength of this layer depends

proportional to the

Pk

is

As a

on and

result,

is

the

D

strongest at midday, and

nightfall. Also, the

the winter.

D

layer

is

layer it

pagatio

Figure

A

simplified look at

how shortwave

radio signals can be received with help

from the ionosphere.

On

the lower frequencies (below about 10 MHz), the

signals that are transmitted into

it.

A

D

layer will absorb

great example of this effect

is

any

to tune

AM

(medium wave) broadcast band at midday and then do the At midday, you will hear local stations and maybe a few powerful cross-state stations. But with nightfall, the band comes alive and stations from across the country are audible. You have just witnessed the

across the

same

at night.

effect of the

The E

D

layer.

much

D

higher, and it has most radio signals, but it will sometimes refract shortwave signals especially those above about 14 MHz. So in the summer months, the higher frequency amateur bands are particularly "hot" during the daytime when the lower frequency bands are being eaten alive by the D and E layers. layer

is

like

the

layer,

a few redeeming characteristics.

except that

The E

it

is

a

bit

layer will absorb

—

One

of the

most

interesting characteristics of the

skip. During the sporadic

E

skip,

some higher

E

layer

is

called sporadic

frequencies in the lower

E

VHF

region, which don't normally skip, suddenly skip for very long distances.

Sporadic E skip at the right

is

somewhat common,

but you have to be at the right place

time for a good opening.

247

9-1

Shortwave radio

One

time

I

the car

in

lived in a small

apartment and would watch television on a small,

TV that my sister had given me. One severe this TV was that my sister had broken off the whip

beat-up black-and-white

disadvantage to using

antenna a few years

enough

So

earlier.

it

didn't receive that well, but

would come

I

was

close

anyway. One evening at sunset, channel 4 from Pittsburgh started to fade out and was replaced by another signal. In a few minutes, KHAS, from Hastings, Nebraska, was coming in loud and clear. About 10 minutes later, KHAS was gone, and the regular stations were back.

The F layer

to Pittsburgh that a handful of stations

makes most shortwave and medium wave skip possible. This and it remains ionized

layer

is

in well

several hundred miles above the Earth,

much

day and night; however, unlike the other layers will refract signals back to the Earth. Because the F layer is so high above the Earth, signals often skip over very great distances from the F layer, sometimes several thousand miles. As a result, it is easy to hear international broadcast stations with clear signals from around the world. throughout

of the

(under most circumstances), the F layer

The ionosphere,

have a number of above the top of the shortwave band will normally cut straight through the ionosphere and travel into space, but the lower shortwave frequencies (as stated previously) are often absorbed by the ionosphere. As a result, there are no constantly perfect frequencies; "best" frequencies depend on what the intended audiences are, the time of the year, condition of the ionosphere, and the like. peculiarities.

skip conditions,

One

oddity

is

and

signal absorption

that frequencies

Another variable that dramatically affects listening is the skip distance. Long skip is not necessarily the most desirable condition. For example, it is common to listen to the 20-meter amateur band (approximately 14 MHz) during the daytime hours and hear a station from a distant country, such as Australia, talking to someone in your state. The problem is that you will probably only hear the station in Australia, not the one in your state! Thus, if you are an amateur operator, you would try a frequency on a lowerfrequency band if you wanted to contact someone that close.

The same holds

true for broadcast listening.

the United States broadcast

on the

A number

of private stations in

41 -meter band (approximately good for only close communications

so-called

7300 to 7500 kHz). This area is fair to during the day, but at night, the signals get out for thousands of miles. At night

(at

my

location), these stations often

rapidly fade in

7i

248

and

out.

The problem

is

drop to about

that

I

am

Vi

strength,

and they

too close to the transmitter

hortu/ave broadcasting

for good reception at that time, and most of the signal is skipping over me. These problems are virtually unheard of at AM (medium wave) and FM broadcast frequencies, so most people are stunned that they occur on the

shortwave frequencies.

One

factor

makes propagation

you know, shortwave in turn

is

forecasting and theory very complicated.

signals are severely affected by the ionosphere,

affected by sunlight. Daytime and nighttime

same time throughout

the world. This creates

some

do not occur

As

which

at the

bizarre skip conditions,

to say the least.

The

best

day

in

way

to see

your area

is

what frequencies are coming

in at a particular

to either join a shortwave-listening club (so that

time of

you can

see logs of what other people are hearing, or you could read the

propagation forecasts in some of the amateur radio magazines. Or you can use the simple tune-through-the-dial method to figure out what is and isn't audible. In general, the frequencies below 10 MHz will be best at night, and those above 10 MHz will be the best during the day. But the frequencies near this general daytime/nighttime borderline (such as the 31- and 25-

meter bands)

will

overlap and are at least

somewhat

active

all

of the time.

This section has been just a very quick and very superficial look at shortwave propagation, just something to help you become acquainted with how

shortwave signals reach different parts of the world. As stated earlier, shortwave propagation is much more complicated than this and many important terms and characteristics were left out on purpose. It's just too much to cover in a book on auto audio systems.

(^) Shortwave broadcasting Shortwave listening is fascinating because you can be driving down Interstate 81 through Pennsylvania and be listening to Radio Bras from Brasilia. Brazil, thousands of miles away. After you listen to commentaries and the daily lottery numbers via the Ghana Broadcasting Corporation or hear Barry Manilow songs from the Soloman Islands, you begin to realize just how small the world really

is.

Although the shortwave bands are dry rhetoric, there

is still

filled

with quite a

bit

of

propaganda and

quite a bit of interesting information to listen to.

Other than on the BBC. very little rock music can be heard on shortwave. WJCR is one of the only shortwave stations that plays country gospel music, and it plays plenty of it'

249

Shortwave radio

in

the car

of the other selections include: Afro-pop via Africa #1 (Gabon); contemporary Christian and gospel music via HCJB (Ecuador); pop and classical music from Radio Moscow; pop, classical, and jazz music from the Voice of America: a variety of salsa, ranchero, and Andean music from the regional South American stations; and other local and folk music from regional stations around the world.

Some

Shortwave has become much more popular in North America in the past several years because of the Persian Gulf War. This war brought about two distinct realizations: (1) the news media in the United States is not as good as that in other countries (at least in some instances), and (2) Americans are so bad at geography that few people know much of anything about the other countries of the world.

The Persian

Gulf War, and later the situation in the former Yugoslavia, proved shortwave to be very handy, if not invaluable. In the former, the news coverage was excellent over the BBC (Fig. 9-2), and safety warnings to British subjects were especially interesting and somewhat scary to listen to. In the case of Yugoslavia, the fighting was receiving major attention via the European shortwave stations at a time when you were lucky to read about it on the back page of a typical North American newspaper.

Figure

9-2

SJSEJ

»

The standard, majestic

250

QSL from

the

BBC.

Shortwave broadcasting

But

BBC. Radio Canada North American pirate stations all offer up some comedy programming. Much of this is of the very dry and all is

not entirely serious on shortwave. The

International,

and the

vast majority of

witty type (Fig. 9-3).

Figure

9-3

Figure

9-4

A

sticker from the pirate station Radio Airplane.

number

head unit that covers the have an affinity for) is the ability to stop at stoplights with the raging drum music of Radio Togo (Fig. 9-4) cranked up and the car windows open. It's a great way to surprise people! In

all.

there are a

shortwave bands.

The

tiny,

One

of reasons to purchase a

of the lesser reasons (that

I

still

finger-shaped country of Togo punches a powerful

signal out to the world

on 5047

kf

I/.

251

ave radio

in

Auto audio shortwave equipment Unfortunately, shortwave radio

America,

let

is

virtually

ignored by most everyone

in

North

alone by the auto audio manufacturers. Presently, the only

company that manufactures head units with the shortwave feature and markets them in North America is the North American branch of Philips, Dutch electronics

A

the

giant.

number

of Philips' head units contain the 48-meter shortwave broadcast one small chunk of the shortwave spectrum), but this range would at least allow you to hear some of the shortwave giants, such as Radio Moscow. Radio Canada International, Radio Netherlands, Deutsche Welle, Voice of America, and the BBC during the nighttime hours. These 49-meter shortwave head units include the DCC-821 and DCC-811 DCC cassette decks, the DC-942 CD deck, the DC-722 cassette deck, and the DC-532

band

(just

cassette deck.

shortwave listening goes, the real standout among the Philips one of its lower-end units, the DC-Ill (Fig. 9-5). This radio receives everything from 3170 to 21,910 kHz (90 to 13 meters). Also,

As

far as

line is

(ironically)

this

been known for high fidelity, sound bearable and sometimes even quite good, which is a great feat. The DC-Ill has received a number of reviews in the shortwave hobby press, and every review that have seen has been very positive. It has probably received the most overwhelmingly positive reviews of any receiver that have ever

makes shortwave, a medium

unit

that has never

I

I

seen, probably mostly because of the lack of competition in this continent.

Figure

9-5

The Philips DC-777 AM/FM/SW cassette

The DC-Ill can be

radio.

a bit difficult to find from the regular auto audio outlets, from most of the major shortwave dealers, such as Gilfer, Universal Shortwave, Grove Electronics, and the Electronic Equipment Bank

but

it

252

is

available

quipme

(see the Sources in the back of this book for more information). As this book was nearly completed. received word from Philips that the DC-Ill has been discontinued and that "no successor has been planned for the time being"; however, a number of these models are still available from Philips car 1

stereo dealers and shortwave radio outlets. Hopefully. Philips

will

soon

find a

replacement for the DC-777!

The 1991

edition of the

World Radio

TV Handbook

reviewed two other car

stereos with shortwave reception that were available in Riyadh, Saudi

Arabia. Although the correspondent mentioned that at least five different

mentioned in this book were the Neither were rated nearly as highly as the DC-777. and it probably doesn't matter anyway. Chances are that in your part of the world, certainly here in North America, they aren't available. And as fast as the different models of head units change, chances are that these particular models are no longer available. models were Pioneer

available, the only

KE8700 and

Either way.

if

you

two

the National

live in

that he

CQ800.

parts of the world

where shortwave plays an

Europe, Africa, or the Middle East, you might find some other shortwave head units available. But if you live in a region such as North America where shortwave is mostly ignored, chances are that the important

Philips

role,

such as

DC-777

will

in

be your only option. Maybe some other company

will

see the practicality and usefulness of adding shortwave bands to an auto

head

(J)

unit

and begin manufacturing them.

Antennas work well for receiving stations on the same antennas will operate well for receiving stations

Like the standard car antennas that

AM

(MW) band,

these

on the shortwave bands. These auto shortwave radios amplify the radio signals so that the receiver works well even if the antenna is much too short you are

for the frequency that

listening to.

will soon try is to connect an amateur radio whip that antenna (made specifically for two-way operation in one of the amateur shortwave radio bands) to my DC-777 to see if the reception improves substantially. (For more ideas on antennas that will boost car-bound shortwave signals and also those on AM and FM, see chapter 7, which

One experiment

I

covers auto antennas.)

253

jam Amm MW aWKF MW a

Shortwave radio

in

the car

Shortwave information Unlike the

AM

(MW) and FM (VHF) broadcast bands, you must

air. It's like

receive

some

you want to keep track of what's on the the old "don't know the players without a scorecard" adage; you

shortwave broadcast information

if

need a shortwave-station scorecard.

The

difference

between these broadcast bands AM and FM bands all stick to

is

North American

that the stations

their

own

on the

single frequency

and

The only simulcasts allowed are when one AM and one FM station are owned by the same company and both stations simultaneously air identical programming. The only stations that change formats during a broadcasting day are the few low-power community stations still left and the format.

college radio stations.

Shortwave broadcasters are completely different. Except for the conservative religious stations in the United States and the handful of local commercial outlets in Latin America and a few other scattered parts of the world, the shortwave broadcasters are all governmental branches that periodically

programming that is beamed to different parts of the meet these needs, the typical governmental broadcast a program that is anywhere from 30 minutes to 2

deliver a variety of

world.

To be

station will

able to effectively

hours

in length.

Then

the station

will either

switch antennas and broadcast to another part of

the world, or switch languages again. Because

and broadcast another program, and switch

some shortwave

stations broadcast in as

many

as

80

different

languages, you can imagine the enormity of these operations! Also

remember number of

that these stations broadcast

on many

different frequencies in a

For example, according to the 1993 edition of the World Radio TV Handbook, the Voice of America operates 36 different transmitters in North America alone; VOA also has numerous transmitters currently operating from many other countries. different broadcast bands.

Speaking of relays

many

in

other countries, although

stations broadcasting directly

from

their

it

is

own

quite possible to hear

country (some stations,

such as those as far away as Radio Australia, can be heard quite well in North America directly even though the transmitter is on the opposite side of

some have relay agreements with other countries, and these programs can often be heard with tremendous signals.

the world),

254

Shortwave information

For an example of distant transmitter sites, the Voice of America, BBC. and Deutsche Welle (Fig. 9-6) all have transmitter sites on the island of Antigua in the Caribbean. As far as relay agreements are concerned, The Voice of

WYFR (California). Radio China International (Mainland China) has relay agreements with Radio Canada International, and Radio Moscow's North American service has been relayed for years from Radio Havana sites in Cuba. Free China (Taiwan) has a relay agreement with

Figure

Stxt»rln d*r

Sendemetz

Deutsche Welle

Bumt»$rmpubiiti

Deutsche Welle uses these transmitter and relay station

sites for

worldwide

coverage.

It was mentioned earlier that frequencies often change. This is because the same bizarre ionospheric conditions that make worldwide radio reception

possible also easily affect and disturb radio reception. For example, in the

summertime, the noise increases on the lower nighttime bands especially and the high frequencies often spring,

many

become more

during the winter, the lower frequencies therefore,

channels

many

in

reliable.

As

a result, during the

stations switch to using primarily higher frequencies.

the

stations

move some

become

quieter and

of their frequencies

more

down

Then reliable;

to lower

autumn months.

255

9-6

Shortwave radio

To make

things even

in

the car

more complicated, every 11 years

radio conditions run

through a sunspot cycle, which improves reception at the height of the cycle and damages reception at the low point of the cycle. During this cycle, there are times

when

frequencies above a certain point are totally ineffective for

reaching an audience, the peak of which

frequency, and there are other times

is

when

called the

maximum

usable

frequencies below a certain point

will be totally ineffective, the peak of which is called the minimum usable frequency. These conditions force the international broadcasters to have monitors in various parts of the world listening to see if the signals are clear

and strong.

As a

If

move its broadcasts to another frequency. changing conditions, you can see how to have current information on hand.

not, that station will

result of these constantly

important

it

is

Several different monthly shortwave magazines are available, and a

and organizations

number

speedy and informative newsletters. Considering the nature of vehicular shortwave listening, you would probably be more likely to casually tune in the news on the BBC than be bouncing all over the shortwave bands, catching specialty programs from the smaller outlets. Subscribing to one or more of these periodicals might not be as useful to you as the subscription money that you would otherwise save. of different shortwave clubs

offer

Still, if you have any interests in shortwave listening (and surely you would if you purchased a DC-777. or one of the other models), then subscribing to shortwave magazines or newsletters is certainly worth the money. Over the years, have subscribed to 14 different shortwave magazines and newsletters. To me, they have been quite an interesting lot, and they are well worth the money. I

Bookwise. two annual "master references" exist on the subject: Passport To World Band Radio and The World Radio TV Handbook. Both of these references are quite large, thorough, and accurate. The difference between the two is that Passport is much easier to use for program listening, but the WRTH crams tons of useful and trivial information into the book. Both are

and different, so regularly pick up copies of both. If money is a concern, you might consider looking around for older copies of these books.

quite useful

I

Sometimes I fill in my collection of the books by picking up cheap used copies from friends or classified ads, or at shortwave-listener gatherings. you want

to pick just one newsletter or magazine, you should try one with amount of general-interest material (Fig. 9-7). Popular Communications (available at newsstands in North America), Monitoring Times (available from Grove Enterprises). Radio! (available from Radio If

a large

256

Figure

Some

of the shortwave magazines.

Shack

outlets),

and Shortwave Magazine

or by mail overseas) are well

all

(available in the

United Kingdom,

glossy-covered magazines that cover the hobby

and feature a great amount of basic information.

Otherwise, the club newsletters The Journal, from the North American

ShortWave Association (NASWA). and

ODXA,

from the Ontario

DX

Association, are both excellent for general-coverage shortwave listening.

you

live in

If

a different area of the world and you are interested in shortwave

periodicals, then

Handbook and

you should read the club

write for information from

listings in

some

the

World Radio

TV

of the local clubs.

257

9-7

-^

10

Installation

techniques and real-life stories Aside from the decisions that you need to make when purchasing equipment for your system, the most important work involved in having a "great-sound" is the actual installation. The planning and methods that you use to install your system could make a great difference in its performance. Or you could cause great damage to one or more components if you install something wrong.

car audio system

The

first installation matter is to read the manual and installation directions each piece of equipment that you are planning to install. Read over the information, and get a good grasp for the task. Then when you start, make sure that you have the tools that the manual recommends. Even if you are

for

familiar with the techniques of installing audio systems in cars,

258

make

sure

you have a copy of each manual with you; the and other information should also be handy. that

specific wiring

diagrams

a bit different. A huge number and every different car has a different set of acoustics, installation, ground, and wiring problems. Every new installation will involve different problems. Because of the "if-then" Unfortunately, every auto audio installation

of different audio

components are

nature of the work,

it

is difficult

utterly confusing the issues.

As

is

available,

to cover everything in a chapter without

a result, this chapter thoroughly covers

several specific installations.

Each section is a complete account of the installation process for each car. Methods are skipped only when they would otherwise be repeated from previous sections; in these cases, references are descriptive sections rather than

make

this

made

chapter

to the previous

totally

redundant. Because

am a firm believer in the learn-by-your-mistakes educational method, all of my stupid errors are also recorded here. So make sure that you read each I

section to the end before following the steps that originally

made some

I

took! In

decisions, then found that they

some

cases,

I

were creating problems

by the end.

981 D The 1

VW Rabbit

relatively inexpensive but complete installation

When

I

family's

decided to go ahead with installing a good sound system into my workhorse car. ran into a few nonstandard problems that require I

to be understood. Because am somewhat of wanted a no-frills utilitarian car with great gas mileage, something that was cheap, but solid and dependable. The only car that met this criteria was the diesel Volkswagen Rabbit. The days of Fahrvergnuegen have long since swept away the Rabbit, so sought after a used one.

some background information a spendthrift,

I

I

I

After

months

those

lots that

of waiting

and searching.

rusted-out "50s-era flatbed trucks.

however,

one car

my

that

found a 1981 model on one of

The common denominator was

Rabbit looked clean, and even with 120.000 miles,

of the nicest looking cars

was

I

has everything from rusted-out '70s-era station wagons to

it

was

in a

on the rather homely

front-end accident, and the

either puttied or replaced, then the

rust;

was still The catch for this hood and fenders were it

lot.

whole car was repainted.

A

few days

259

& tF

M&J0MfJJJFJW1WJKF

MSFJVM¥ SWMWMF£W^FMfMfJSF

r

Installation

after

I

techniques and

bought the

car,

real-life stories

the battery went dead and later the alternator died (the

case was cracked in the collision).

was none. Whatever had been owner before scrapping it. Considering that the car was not modified anywhere else and that it was strictly an economy car. it seems as though the stock audio system stayed in until the accident. Why anyone would ever want to strip stock 10-year old 3.5" (8.89 cm) speakers out of a car is beyond me. Nevertheless, the 3.5" (8.89 cm) round speakers were removed from the dash, the 6" x 9" (15.24 cm x 22.86 cm) speakers were removed from the rear deck, and the head unit was gone. In addition, the wiring harness was sliced in the dash, revealing only three wires, and all the speaker wires seemed to have been

The in

was

stereo system

the car

was

also interesting; there

evidently salvaged by the previous

stripped out with the speakers. it was money, and courage had prevented me from taking on the stereo challenge. When decided that had to put in a new system, considered what would suit my needs. The bottom line was that wanted to be able to play music that liked in the car. Next, wanted a system with enough power to override the sound of the diesel engine for under $500. decided to splurge, and went with a head unit that also had

After only driving to the sounds of a rattling diesel for several years,

time for a change!

A

lack of time,

I

I

I

I

I

I

I

I

the option of shortwave reception.

The

didn't have a show car (and didn't want one) helped as well. I want to fill the trunk with speakers or amplifiers or concrete. And didn't want a pounding set of subwoofers that could stop a pacemaker or shatter windows at 30'. went with a Philips DC-Ill (the only AM/FM cassette deck with shortwave), a pair of Pyramid 2-way 3.5" (8.89 cm) speakers for the dash, and a Harrison Lab 3-way Power Mowse speaker system for the rear deck. All of the wiring in the sound system is aftermarket cables from Audioquest (Fig. 10-1). fact that

I

didn't

I

I

Speaker system wanted to put the speakers in the stock locations, except for the subwoofer. and thus save a great deal of time and demolition. When received the I

I

speakers, however,

I

when

discovered that the speaker10-2) at each side of the rear deck were made for 4"

realized that

I

erred

I

mounting positions (Fig. x 6" (10.16 cm x 15.24 cm) speakers. bought 6" x 9"s (15.24 cm x 22.86 cm) that were wider than each of the speaker positions, so couldn't even I

I

consider cutting larger holes for the

260

new

speakers.

I

could have returned the

1981

VW

Rabbit

Figure

10-1

DC 777 Pyramid 3.5" speakers

Pyramid Radio

3.5" speakers

DC

Shack box

777

speakers

Power

Mowse speaker system

Pyramid

Power

3.5" speakers

Mowse

DC

speaker system

777

The evolution of the system

in

the

VW Rabbit.

6" x 9" (15.24 cm x 22.86 cm) for speakers to match the holes, but wanted a beefier sound from the back, and didn't want the 12" woofer drown out the coaxials. 1

I

After staring dumbfoundedly into the trunk for the possibility of building hit

new speaker

me. Removable speaker cabinets.

I

to

some time and considering

decks, the "easy," practical solution

wanted

functional, easy-lift rear deck, so the cabinets

to keep the ugly, but had to sit on either side

of the

261

/£

Installation

Figure

techniques and

real-life stories

10-2

The standard rear-deck speaker-mounting position in the

deck to hold

it

They

up.

to be easily disconnected

VW Rabbit.

needed to be solid in construction and be able and pulled out of a slot from the inside wall of each

also

rear fender.

I

picked particle board for the box material and decided to line the inside

with insulation for

board

is

maximum dampening and

strong, very dense,

and

it

reflection reduction. Particle

doesn't have large flaws,

like

most

plywood. Fiberglass insulation or cotton/polyester batting are very common types of speaker dampening materials. based my material choices in part on I

what materials were the best for the job and in part on what was already on hand. had leftover particle board shelving and a roll of fiberglass insulation in the basement, and this made the decisions much easier. I

Then as the deadlines for this book began to close in. thought about buying premade speaker enclosures to save some time. In fact, did order a pair, and prepared them with carpet and a set of speaker terminals. But in the pinch (and for more variety between the systems), used a Harrison Lab Power Mowse 3-Way system in the back. This system is a stereo pair of midrange and tweeters, a transmission-line subwoofer, and a 100-W I

I

I

I

haven't seen any and it's convenient because the only installation involved is running the wiring and the box can be removed at any time. Also, considering the cost of rear speakers, a subwoofer, and an

amplifier

all

built into

a relatively small, carpeted box.

other companies offer anything

amplifier, plus the extra cost of convenience, the

rather inexpensive.

262

I

like this,

Power Mowse 3-Way

is

1981

The

actual installation

VW

Rabbit

work

After looking through the manual a few times for specifics,

embarked upon on the checklist was the head unit. The Rabbit's dashboard radio hole is for one of the old two-knob head units, and the DC-Ill is a standard DIN size. removed the metal mounting sleeve from around the head unit and held it up to the original radio's mounting hole. the mind-expanding

ritual of installing

I

the auto audio system. First

1

I

used a pencil and traced around the outside of the mounting sleeve onto

had the tracing visible, cut inside of the hand saw. The plastic was thin enough that the cutting was easy, and by making a few diagonal cuts from the knob holes, had no problem cutting out the corners without mangling them. the black plastic dashplate. After

I

1

pencil lines with a tight-fit

I

tried to draw and cut along the lines so that they were relatively straight and accurate, but was a bit off. This was no big deal because the lip of the mounting sleeve covers nearly all of the rough plastic edge. The tiny bit that wasn't covered was overshadowed by the overhang of the front of the head unit, and these rough spots were tough to notice in the solid black plastic anyway. I

I

One major wires.

The

question that

I

had with the system was the identification of the had three snipped wires: blue/white

Rabbit's wires were cut, so

I

assumed that the blue/white striped wire was for the lights, the red wire was connected to the battery, and the green wire was ground. The head unit had a spade lug on the end for a chassis connection, but couldn't find a good close chassis ground on the car. used a multimeter switched to the continuity mode and touched one probe to the green wire and the other probe to the ground shield of the cigarette lighter (Fig. 10-3). The tone sounded and everything was go. and

striped, green,

red.

I

I

I

I

stripped the insulation back about

with a knife. This stripper, both to

isn't

'/"

mm) from the ends of the wires and you should use a wire

(6.35

a very safe practice

be safe and to keep from breaking the individual wire

placed each wire from the head unit inside of the terminal block and screwed each shut with a tiny screwdriver. Afterward. matched up the wires from the car and screwed each one into the appropriate hole of strands.

Then

I

I

the terminal block.

263

techniques and

Installation

Figure

real-life stories

10-3

The Philips DC-777 mounted

in

the dashboard.

Next came the speaker assemblies. The speaker wires were missing from the so had to feed new ones from the head unit to the speaker locations. The area behind the dashboard was packed with wire harnesses, heating vents, and plastic dead ends of various sorts. There was no way that could either feed the wire through by itself or run it through with my hands; the space was too complicated and too small for my hands to fit through. car,

I

I

So

I

dismantled a coat hanger and straightened

it.

I

taped the end of one

speaker wire to the end of the coat hanger. worked the end of the coat hanger through the dashboard and into the hole for the head unit. After this was completed, did the same maneuver with the other side. I attached the I

I

front speakers

and screwed the other ends of the speaker wires to another

terminal block.

more permanent worked on the first try! So stuffed all of the cables back into the DIN hole, then fed and snapped the head unit in place for the time being. By the time that the head unit was mounted in the dash, it looked like it was meant to be installed there (Fig. 10-4), which was a nice feeling after a I

tested the system before pushing everything into a

position. Voila!

It

quickie hack'n'slash operation.

264

I

1981

VW

Rabbit

Figure

A

multimeter can be very; when working on an

useful

installation.

Everything sounded relatively good, considering that

I

only had a pair of 3.5"

(8.89 cm) two-way speakers mounted in either side of the dashboard. Unfortunately, the speaker

had cut

off the

grill

covers couldn't be put back on

I

was

I

thought that one of

driving to work, the speaker

my

hole was entirely metal, and

it

it

was

connections from shorting against its

on the passenger

coworkers (who

stepped on the wire and shorted

the speaker in

until after

I

metal-screw installation flange off one side of each speaker. As

I

sometimes

out. Instead. difficult to

began

call

to short out.

a klutz) had

discovered that the speaker

I

prevent the speaker

this obstacle.

hole and tightened the screws:

with electrical tape to shield

side

As a temporary I

fix.

I

moved

eventually taped the leads

them from contacting the hole (which

is

a

good

practice to avoid potential electrical shorts).

work brought up a few more problems that hadn't initially The shortwave radio had a 'whump, whump" noise whenever the engine was started; this interference sped up in proportion to the speed of the engine. guessed that this interference was coming from the alternator. also noticed that the heavy engine noise and the deep rattles throughout the

The

drive to

I

noticed.

I

I

car canceled out the lower audio frequencies.

265

10-4

Installation

As a

result,

techniques and

real-life stories

the system's sound was even harsher and tinnier than

I

had

expected from just the front pair of speakers. The last major problem that encountered was that I only seemed to be hearing one of the audio channels through both speakers; this was particularly noticeable during "Lights Out" 1

by the Angry Samoans.

home that night and pulled the head unit out. The first thing that checked was the speaker connections. Rather than check the connections on the head unit when I initially hooked them up, I just connected the two speakers sequentially on the wires and didn't notice that they were both for the I

took the car

I

right channel.

didn't yet

Mowse's

and added several more speakers. power cable to operate the Power improvised with a set of small boxed home/auto

reconnected

I

have

all

this wiring

I

of the connectors or

amplifier, so

I

speakers (scrounged out of a college dumpster at the end of a semester). In addition to these speakers,

I

had a Harrison Labs "Power Mowse" amplified had

have the line-out connector for the head unit, so to avoid the amplifier, and could only connect directly to the speakers. Another dilemma was that I only had two channels to run four speakers. speaker box.

I

didn't yet

I

I

Using

just the

Power Mowse

in the

back without the amplifier provided good

bass response, but the sound totally lacked midrange.

On

the other hand, the

boxed speakers provided nice, smooth upper midrange and treble response, but the loud, deep car noise nulled out everything to the extent that the audio sounded very tinny. So connected the one channel of the head unit to one of the two channels of the Power Mowse. parallel connected the other two speakers (they were 8 ohms, so the parallel connection resulted in 4 ohms to the head unit's amplifier) to the remaining channel of the head unit. The back speakers were all in mono, and although the stereo imaging was certainly not overpowering, the audio wasn't bad. The rear speakers helped considerably to mellow out the raspiness of the front speakers. small

I

I

When

I

got tired of having the loose audio cables repeatedly pulled out of

the speakers in the rear deck,

carpet of the interior.

I

decided to actually run cables under the

The carpet was easy

to pull back from the interior of the car; unclip the strips around the edges of the doorframe and pull the carpet away from the adhesive strips. I made all of the proper connections

ends of the wires, then duct-taped the wiring down to the body of the its length. made the connections at the other ends of the wires and moved the carpet and the doorframe edges back into place. Easy. The most demanding part was keeping the wires from being readily noticeable, but by having them come out in the trunk, behind the backseat, at the

car throughout

this

266

was not too

I

difficult.

Car noise reduction Excessively loud interior noise

was the worst problem

audio system's noise but the car's noise, which was the engine noise canceled out eliminate

some

much

unwanted

of this

that

I

faced

difficult to

—not the

overwhelm. And

of the lower frequencies. In order to

noise.

I

started to use sound-deadening

Numerous brands of sound-deadening material are went with Accumat from Scosche. Most types of sound-

material in the car. available, but

I

deadening material are available

in different

forms, such as that for doors,

and hood headliners. and that which "spreads on" for difficult mounting locations, so be sure to choose the proper type for your specific application. floors,

My

were the doors. To access these

removed the door wedged a screwdriver behind the decorative doorpanel padding. This padding was connected to the door with a series of plastic connectors that could be popped out of their holes. Unfortunately, also discovered that they can also easily be popped out of the padding, and lost one. One method to remove the padding that worked well for me was to wedge my hand in behind the padding and find where it was connected. then wedged a flathead screwdriver in behind each connector so that it wouldn't pop out of the padding. first

targets

cavities.

handle and the window crank with a screwdriver.

I

I

I

I

I

After

I

popped

off the

door panel,

rip

it.

then

I

1

found only painted

steel (with

speaker

peeled back the plastic and was careful not to cut the Accumat into pieces that were large enough to cover the

holes) covered with plastic.

holes in the door

I

(Fig. 10-5).

sound-deadening material into the inside of the car, you must back the interior carpeting and clean the interior surface if it is dusty, dirty, or fuzzy (from the carpet backing). Simply cut the sheets of sound-deadening material into appropriate shapes and sizes, peel the backing, and move it into place. Rub it down with your hand or with a roller to remove any air pockets under the material, replace the carpeting over the

To

install

carefully peel

material,

(J)-

The

and reattach the carpet.

future of this system

I'm not sure what the future holds for this system. it

finally disintegrates, like

my

lOth-grade

going to be relatively permanent.

I

gym

plan to use

I

plan to use this car until

So the sound system more sound-deadening socks.

is

267

installation

Figure

techniques and

real-life stories

10-5

The front door panel before material was installed.

(left)

and

after (right)

Accumat sound-deadening

material inside (especially inside the trunk) so that the Rabbit will hopefully be as loud inside as a jeep, not a

Sherman

tank.

I'm also considering replacing the front speakers with better units that don't distort in the

lower treble frequencies.

I

am

presently considering using a set of

2.5 component speakers by audiophile to considerably improve the sound the front. While I'm at

the Rabbit to

make

it

a

it,

I

might also do a

more

little

hospitable place. With any luck, the

speakers and the quieter Rabbit

will vastly

in

cosmetic work to the interior of

improve the sound of

new

this

front

system.

1975 Ford Granada

The

absolutely cheap,

scavenged system Not everyone has a few grand to blow on a car audio system. In fact, spending that much money on a system could cause a number of problems

3l

268

1975 Ford Granada

If your money is tight, you any available means to scrape together a decent system.

with your spouse or possibly with creditors.

need

to use

will

One of my friends was in such a situation. He was unemployed and his wife was pregnant. He found a job and after about eight months, they were starting to pull themselves out of debt. They wanted an inexpensive, rugged family car. so they bought an old 1975 Ford Granada for approximately $300. Obviously they didn't want an expensive sound system, nor could they afford one. The Granada had a stock AM radio in it. but they were tiring of hearing the same mix of music and talk shows. They just wanted an inexpensive but decent sound system for a bare minimum. With some time spent scrounging around, they were able to find sort of a complete system for $44. The head unit deck is a Sherwood AM/FM cassette deck that was purchased used for $40. It was bought on sale by the original owner for $105 several years earlier. (She never had it installed in her car then and later she just wanted to get some money for it.) The Granada's front speaker is simply the factory speaker. The rear speakers are a cheap pair of surface-mount speakers that my friend had installed in a VW Bug about 10 years ago. In the meantime, they had been sitting idle in a junk box. The extra $4 was from purchasing two 8-connection terminal blocks for the wire connections (Fig. 10-6).

Figure

Stock speaker

Rear deck

Head

speakers

unit

A

(J)

system drawing for the Ford Granada.

The

installation

Unlike the installation that follows

remove

in

the Granada.

The

in the

front plate

next section, everything was easy to

was the

first

to go.

We

removed the

screws along the edges of the plate, then pulled the knobs off the old radio. jammed a screwdriver blade into the spring clip to remove the headlight I

I

knob. The sleeve behind the headlight knob was a

bit

tougher, but

my

friend

269

10-6

Installation

suggested that

I

techniques and

should try to unscrew

real-life stories

it.

did

I

and

it

pulled

off.

After

I

pulled

the rubber gasket back from the steering column, the front plate pulled right

Then we unscrewed

off.

the nuts around the dashboard, and

it

also pulled

right off.

The

AM

(MW)

was held

by a plate with four hex nuts. large nuts that screwed onto the posts of the potentiometers held the front plate to the head unit. thought that they might be difficult to remove, but pulled them off with the spark plug adapter on a ratchet. old Philco

radio

unscrewed them and pulled the radio

in

out.

I

Two

I

I

OK. except that the unit had no ground wire. an approximately 4-inch-long steel clip was screwed into the back. This clip served as a ground and a mounting bar (to keep the weight off the potentiometers in the front panel), and it slid into another clip that is grounded to the chassis (Fig. 10-7). In spite of the generally crude technology of this car and head unit, this ground system was truly ingenious. All

the wires checked out

Instead,

Figure

10-7 The

rear of the stock Philco showing the

AM radio, '"

snipped

-*'

ground

clip.

combination wire stripper/crimper tool, them into an 8-position terminal block. The Sherwood head unit is peculiar in that it has one ground wire for the head unit and one ground wire for all of the speakers (usually, each speaker has its own positive and negative wires). While was connecting the I

off the wires with a

stripped off the ends, and then screwed

I

wires into the terminal blocks,

and mounting the speakers

The metal

front plate

in

my

was hunting down some spare wire the back window. friend

had deep cylinders pressed

in.

The bottoms

of the

where the potentiometers run through. Unfortunately, the two cylinders were different lengths (to match the old Philco), and the plate wouldn't properly fit on the Sherwood head unit. We thought about drilling out the cylinder that was too long, but we settled on cylinders have holes in the center,

it in a 20-ton press (Fig. 10-8)! The brute force of the press might have been unnecessary, but it was effective! The plate then fit perfectly, and screwed it on to the new head unit.

squashing

I

^\

270

975 Ford Granada

Figure

Squashing the front plate protrusion with a 20-ton

press.

was another problem that called for an improvisational solution. My up all the wire that he could scrounge for speaker wires: telephone wire, microphone cable, coaxial cable, or a lamp cord. These certainly were not optimum conductors! The lamp cord was #14 copper, and the runs would be less messy, so we used it. The lamp cord was only long enough to make one run to the back. Rather than only connect one speaker or to connect both speakers in parallel. connected the positive left and right rear channels to each side of the lamp cord. My friend had also found a power cord

The

wiring

friend

had

piled

I

from an old appliance.

I

cut

and stripped the wire, which he used to ground

the rear speakers together. (This technique

manufacturers specifically instruct against 3-inch-long

power

were made using

cord.

I'll

is

not normally acceptable;

this technique.)

know what happened!

All of

single terminals of a terminal block that

If

his toaster

many has a

these connections I

had ripped apart.

found a screw in the original radio ground inside the dash, so unscrewed and attached the ground wire. tested out the unit with only the front speaker connected and the sound was weak. knew that the head unit only outputted a few watts per channel, but thought that it would at least be listenable. We connected the rear speakers and they worked fine, although unbalanced in levels. Considering their present condition. wouldn't have been surprised if they didn't work at all. Everything seemed to be in a "thumbs-up condition, and we proceeded to reassemble everything. I

I

it

I

I

I

I

271

10-8

w'JKFJJA

Installation

We

techniques and

were playing a tape

in the

head

real-life stories

unit

came

when my

friend put the dash in

and he thought that I found a fader control and faded the levels forward. Nope, it was merely the difference between having the speaker enclosed and sitting in a 'free-air" position; hence, it was a nice illustration for the importance of elementary speaker place. Suddenly, the front speaker

enclosures,

A

let

to

life,

alone good, tuned enclosures.

system overview

This would probably be considered an absolute no-no system for

many

people because three different "rules" were broken: (1) buying used equipment, and (2) an ac power cord used for audio to rear speakers that were (3) grounded together in a system that was not in full stereo.

Maybe the rules were broken, but in this case, it was effective. The cassette deck looks great in the car (much better than the old radio), and the couple can now listen to FM and cassettes in a multispeaker semistereo arrangement (Fig. 10-9). The sound isn't great, but it is several times better than the old AM radio. This is a vast improvement over what they did have, and for a mere $44. the system was an excellent investment.

Figure

10-9

The

3i

272

installed

head

unit.

1986 Chevrolet Celebrity

Chevrolet Celebrity (J) 1986

The higher-end

installation

High-end auto audio systems can run well into the thousands of dollars. Take show cars in the car audio magazines and you will see systems with customized interiors and speaker enclosures, motorized doors, peculiar electronic gadgetry, and system components that run into a lot of money. The system described for this Chevrolet Celebrity is not in this price bracket, in part, because I don't believe that many people are interested in placing a competition-grade installation in their everyday driver car. a look at any of the

The

benefits in the usable

come

performance

of a competition-grade system just

most of which is eaten up by adding extremely high power and trying to build the system to handle that power. As it is. would consider the system in the Celebrity to be don't need as overkill in nearly every area, except the speakers, because much power as this system will provide and because the DCC head unit is presently priced much higher than it will be in a few years (the high cost of

don't

close to balancing out the extra cost,

I

I

cutting-edge technology).

The system

in

DCC-811

the Celebrity consists of a Philips

cassette player, a Linear

Power

Punch 200ix two-channel

digital

compact

PAII signal processor, a Rockford Fosgate

amplifier, a Harrison

Lab 10" woofer

in its

Power

Mowse bass cube enclosure, a pair of Altec Lansing ALS46 4" x 6" (10.16 cm x 15.24 cm) speakers in the front, and a pair of Infinity 693-Kappa MKII 6" x 9" (15.24 cm x 22.86 cm) speakers in the rear deck. All wires in the sound system are aftermarket cables from Audioquest. Although the

system

is

$2,500

not competition grade,

list

installation

work

(Fig.

first,

I

is

excellent,

and

it

someone

if

would run close

to

else did the

10-10).

Jl Installing the At

it

price, let alone the extra cost

head unit

thought that installing the system

in

the Celebrity would be a piece

The plate in the dash popped out, then I'd yank the old radio, put the new unit in a know that was actually facing in. Little did double DIN adapter, and pop of ice-cream cake (with the nifty frozen-cream icing).

could be

it

I

I

off in a battle-of-wits contest against a jury of criminally insane

geniuses. I'll

let

I

have no proof that the engineers have

this

engineering

mental condition, so

you decide.

273

Installation

Figure

10-10

techniques and

real-life stories

Stock 4"

x

6"

speakers

DCC

Stock

811

4"

x

6"

_/| speakers

I

I

I

I

Power

I

I

DCC

Punch

Mowse

811

200ix

cube 10" woofer

ALS46 4"

x

693-Kappa

6"

MKII

speakers

6"

9"

x

speakers

The system evolution of the Chevrolet

Celebrity.

which made sense because pushed and pulled and grunted. Finally popped the panel out and snapped off the tab in the process, but at least I had it, right? Wrong. found that the panel was attached to the dashboard somewhere around the glove compartment. So First,

I

I

tried to pull out the right side of the panel,

could see the tabs on the edges where they clip into the side.

I

I

I

I

pulled out the domestic-vehicle edition of Scosche's

Encyclopedia for some assistance I

(Fig.

10-11).

discovered that the plate in the center of the dash was held in place by five

PAL

compartment

nuts inside of the glove

were, but they seemed

like

standard nuts.

wall. (I

I

didn't

know what PAL nuts some local

subsequently called

auto parts stores, and they had never heard of I

Autosound

PAL

nuts either.)

could barely reach into the glove compartment to loosen the nuts with the

ratchet, but

I

could slightly turn them. After turning one for a

number

of

checked it with my fingers. It didn't budge. figured that the ratchet slipped off, and went back to work. About 30 minutes later, decided that was wrong and was somehow fighting with magical nuts and bolts. I'm smart enough to not keep fighting magical nuts

revolutions with the ratchet,

I

I

I

I

^\

274

I

1986 Chevrolet Celebrity

TUNERS

CASSETTE

/

/

DISC PLAYERS

DISC

EQ STACK

CHEVROLET

Figure

CELEBRITY

1982-90

Coupe, Sedan and Wagon

4H-5* 'S-'X l-.rO

-i

"V!

.

IN

DASHBOARD Factory Proviuon 4 i 6" Atiermarxet * x 6" or 4" K

IH4

DASH APPLICATION NOTES

IN-DASH INSTALLATION AREA DIMENSIONS WIDTH

HEIGHT

SHAFT CUP OFFSET

REAR DECK F»dory Provision: 6

AMPLIFIER LOCATIONS mnm UNDEB SEAT

IMkER OJS"

REABSiDE

A*ie--na>e'

5'

*

x 9'

6

BANEL.

EQUALIZER LOCATIONS DASH

|

CONSOLE

GL BOX 9*.i!* .iS

•••S» Q« ntMOVt POC«rn

,iT»

•«TAiJ>TCN KIT

«|T

CO*1 »OC«f T LOCATiO*!

$#ACCM OAAOAFTOM afOA^CO

A.

OAtM IMAT

RtOOtf*'

MOO«OirCNS MCOUMCO

«»«M

HXJWD *

'- 'AC'C** iLf CmOMC^AOO

121

Installation information for the Chevrolet Celebrity

Autosound Encyclopedia.

from the Scosche

scotKftt

275

10-11

techniques and

Installation

real-life stories

moved down

to the other end of the panel to try to make some progress unscrewed a number of hex nuts from a plastic panel under the steering wheel and finally pulled the panel off. This gave me access to a number of different wiring harnesses, but they didn't help much.

so

I

there.

I

Unfortunately, the cigarette lighter was also connected to this panel, so

worked my way

inside

and disconnected

switch knob, but was unsuccessful.

was

still

mysteriously bolted

down

The dash was

other directions.

It

in

it.

I

tried to

didn't matter

disconnect the

I

light

anyway because the panel

other locations.

I

tried

working from

sealed from almost every direction, and the

regions that weren't sealed led to nowhere.

was still nowhere near finishing the an alternative route to the head unit, very much like Columbus taking the backdoor to India. The easiest route would be to cut through the panel on either side of the stock head unit, then pop it out. Afterward. I could drill a few holes and the panel could easily be moved in and out of the larger panel. But the panel was recessed into the dashboard, and knew that if tried to cut it, the dash would get ripped up and the panel would have two ragged edges.

After several hours had gone by and project.

I

realized that

I

had

I

I

to find

I

At this point, felt like the car deserved some physical abuse, but we bought it from my Mom and Dad (and it was their all-time favorite car), so making it look like a repossessed special wasn't an option. Finally, I discarded what little pride I did have and scheduled an appointment for the friendly, local Mr. Goodwrench to rip the dash panel out. He did in less than half an hour for only $20. I

I

I

Goodwrench would be was easy to remove with the

mistakenly thought that the humiliating loss to Mr.

my

final indignity.

Wrong

again.

The

old radio

now the slide-on mounting adapter for the new head unit was too small and slid through the dash. looked up the adapter's part number and sure enough. was sent the wrong adapter. In the end, it was no problem because the head unit for the Celebrity was not only much thicker, but it was also much smaller depthwise than the average DIN deck (Fig. 10-12). As a result, the car had a steel mounting bar in a position so that the standard head unit could be bolted in place. found that the DCC811 would stick out an extra 3" or 4" (7.62 cm or 10.16 cm) if tried to mount it with that bar in place. panel gone, but didn't

fit.

it

I

I

I

I

Rather than cutting, smashing, or unbolting the bar (all of which decided to simply move the deck elsewhere. This seemed reasonable, considering that the DCC RDS deck is a high-end deck that uses I

considered),

31

276

I

1986 Chevrolet Celebrit

Figure

The dash of the Celebrity with the front panel removed and the stock Delco head unit hanging by its wires.

what

is

now

"cutting-edge" technology.

there in the dash would

make

it

I'd

hate to have

it

stolen

and

sitting

a great target.

moved the unit to the glove compartment and wired it up from there using section (Figs. the same procedures that were mentioned in the VW Rabbit

1

glove compartment being an out-ofcompartment is within reach and is a drawer in there, but it that slides open with ease. The head unit was relatively stable bottom of the to carpet enclosure speaker shifted a bit. so glued a layer of Now unit. head the of bottom the to Velcro fastened the compartment and

10-13 and 10-14).

In addition to the

sight location for the unit, the

I

it's

I

stable

was

left

and yet removable.

open hole in the dashboard and nothing to fill it. Rather some fancy panels or find some equipment to fit in the hole.

with an

than work up

even connected

back

I

put the stock AM/FM radio back in place. ground and to the illumination wire of the car to still provide the clock's time spree. display and fool anyone who would be on an audio equipment-stealing

just

Maybe not

I

it

to

the ultimate stealth installation, but not bad.

277

10-12

Installation

Figure

techniques and

real-life stories

10-13

Readying the DCC-81 1 for action; all the wires have been connected.

Figure

10-14

A

closer look at the wires in the speaker terminal blocks.

Installing the

speakers

The rest of the installation went better, except that had a nice set of component speakers made by audiophile and decided against using them I

I

because

3l

278

I

would have to

pull off the decorative

door padding

in three

1986 Chevrolet Celebrit

separate difficult-to-remove pieces (the continuing legacy of those

psychopathic engineers). Also, the mounting locations were low

in the door and the sound would be much better from even lesser quality 4" x 6" (10.16 cm x 15.24 cm) dash-mounted speakers. felt that the component speakers would make a good front speaker replacement project for the Rabbit instead. I

The

front dash speakers are standard units that are covered by a plastic grill: both are easy to access and replace. Out came the stock speakers and in went the Altec Lansing ALS46 plate speakers. As stated in the Rabbit installation section,

be sure to wrap the speaker terminals with

electrical

tape

or they might short out to metal inside the dashboard. rear speakers were more of a problem. The 6" x 9"s (15.24 cm x 22.86 cm) were held in with quick-release metal clips so that the speakers hung from the underside of the rear deck (Fig. 10-15). Although the speaker clips were both convenient and well-designed, they were only made to fit those particular speakers and no others would fit in. As a result, the only quasi-

The

convenient way to

fit

the speakers in

was

to use the spaces for the clips to

Figure

An inside-the-trunk view of made quick-release clips.

the stock rear-deck speakers with the specially

279

10-15

Installation

techniques and

real-life stories

and to build a new speaker holder. fashioned two speaker-holding from old metal shelving braces and bent them into shapes that fit the speakers with a pair of pliers. Then went belly-up in the trunk and worked the speakers and the clips into place. Overall, the clips work well, but they lock in

I

straps

I

look a

bit nasty.

inviting

•(•)

A

them

to

Then

again.

I

can't imagine trying to impress

spend some time

in

the trunk of

my

someone by

car!

system overview

in the 1986 Celebrity is excellent by most standards. As far as sound quality goes. doubt that any improvement would be very noticeable to me. Even so, the system could probably drop a notch or two in sound quality and it wouldn't bother me. The ability to play a cassette or DCC tape is great, and the DCC tapes that tested are of incredible fidelity, so that is a

The system

I

I

real plus.

The RDS

feature of the head unit

because

didn't find

was wasted (at least for the time being) any stations that were running RDS. But will certainly be looking on my next drive to Philadelphia or Washington. Also, the 30 watts per channel in the front and the Punch 200ix in the back provided much more power than was necessary to keep a smile on my face. As I can see it, the only real holes in the system are that it lacks either a compact disc changer or head unit and a digital sound processor (DSP). I

Like the Rabbit.

now

I

I

plan to drive the Celebrity for at least five

has 117.000 miles on

more years

(it

permanent. Fortunately, don't feel the need to add sound-deadening material to the Celebrity or to work on the interior because it is still in excellent condition. Except for some minor tweaking. expect that this system will remain relatively permanent. it),

so the system

is

relatively

I

I

990 Geo Tracker The sport utility system 1

@

Another friend of mine has a 1990 Geo Tracker "fun mobile." He bought it new and quickly set about to purchase an aftermarket sound system. Instead of working on it himself or asking me to experiment on his new car (heh heh), he took it to a professional sound installer.

280

1990 Geo Tracker

The

picked out something to

suit the special design and uses of a had a growing collection of compact discs, so he wanted a CD head unit. Because his Tracker is a convertible with only a fabric roof between his equipment and a potential thief, he picked a head unit with a detachable faceplate. The Tracker has no rear deck or rear provision for speakers, so the only option was a set of box speakers in the space behind the back seat.

installer

sport-utility vehicle.

My

friend

The complete system

consists of a Pioneer compact disc head unit, a Targa Lanzar box speakers, and a set of Jensen 4.5" speakers

amplifier, a set of (Fig.

10-16).

Figure

Jensen 4.5"

speakers

Lanzar

Head

Targa

amp

unit I

A

box

I

I

I

speakers I

system diagram for the Geo Tracker.

Although

I

in the installation process,

wasn't involved

The panel around

simple procedure.

With no old head

unit to

remove, the

unit to the eagerly awaiting

power

it

should have been a

the head unit can be easily unscrewed. installer

could just connect the head

wires. Next, the front speakers

were

merely drop-ins for the factory holes.

The

amplifier

was placed

in

the only possible place, under the driver's front

seat (Fig. 10-17). This seat slides a considerable distance; therefore, perhaps

the installer did not have to

remove the

seat to install the amplifier.

necessary, seat removal probably was not a

engineers also worked on

The

difficult

If

task (unless the Celebrity

this design).

rear speakers, which are the final element of this installation, are merely

sitting in the

back.

No

installation

work

there.

281

10-16

al-life stories

Figure

10-17

The amplifier mounted under the

A

driver's seat.

system overview

The system works

quite well considering the vehicle that

it

was

installed in.

Although the sound is clear and loud from the rear speakers (Fig. 10-18). the stereo imaging is fair to poor because they are wedged in the space behind the back seat and facing the tailgate. Another problem is front speakers that are located in the lower portion of the dash and face downward! They might sound good at shin level, but they are virtually inaudible at any other time (Fig. 10-19)! In fact, after many hours in this vehicle, never even knew that it had any front speakers until started writing this book and asked/stated, "Your car doesn't have any front speakers, right?" A real improvement here would be a set of component speakers in the doors. I

I

The head

unit

works quite

(before the unit

is

warmed

up) and

when

driving over train tracks

potholes. This skip problem (although not a major issue)

head

unit,

weather and seems to be in the

well, but discs skip frequently during cold

not the installation techniques.

can't say that would do much differently in this system (other than using door speakers), and it is a good model for what you can expect from a system in a sport/utility vehicle. must admit that if my friend were doing it all over again, would push him to shop around and install the system I

I

I

I

himself.

3\

282

The

overall savings are incredible.

The box speakers

fit

The stock front speaker

Figure

10-18

Figure

10-19

nicely behind the backseat.

locations, which

aim

at the passenger's shins.

283

Installation

techniques and

real-life stories

Conclusion This chapter only covered four rather basic systems, none of which involved

custom

fiberglass enclosures or motorized panels or doors.

topics are

more

in the car

To me, these

repair/customization genre than in auto audio.

these systems are all extremely different and show the different approaches that can be taken (and often must be taken when trying to assemble an auto audio sound system). Even if you take the brute-force approach and modify your car extensively, you will find that your installation will be heavily influenced by the physical characteristics of your car. Just be prepared to be flexible, creative, and open-minded, and you can install a system that will suit your needs. Still,

284

Repairing car audio systems Nothing

is

worse than hopping into your

car.

ready for a

trip,

only to find

pounding the dashboard, and although if you do it with enough

that your car stereo doesn't work. Screaming,

cursing won't help your system a

bit.

rhythm, you might eventually land yourself a recording contract. will be minor, and you can take it to a local shop to have it repaired for a low price. Chances are that even if the problem is minor, the repair will still be costly. Either that or the shop will just suggest that you buy new replacement equipment. Don't even bother with the screaming, pounding, and cursing bit in this case because the repair technician won't be interested; he or she can't sign you to a major recording label anyway. If

you're lucky, the malfunction

car audio

Repairing a problem with an audio system usually involves nothing more than replacing a fuse, checking wiring connections, or checking the wiring

Unless you are friends with an installation shop,

you

will

itself.

you are a regular customer at an pay plenty of money to have someone else make installer or

285

Repairing car audio systems

the minor repairs. Aside from saving great

way

effort will in

to learn about

pay

its

money, troubleshooting your system

arrangement, connections, and

off in the long run, enabling

you

to

how

it

works.

is

a

The

do more work on a system

the future.

From an

electronics repair point of view,

1950s have passed. and bolted into large

In

it

is

both good and bad that the

those days, huge, well-built components were screwed

steel cabinets.

The parts were built well enough that down frequently. And they were large

they were expensive, but didn't break

enough

that they could be replaced without difficulty. Today's advantages are

much less expensive components and miniaturization. Tiny components are crammed so tight that it seems that only a talented baby with tweezers could have assembled the circuit boards. The disadvantage is, in turn, that only that same

talented baby could disassemble the board without destroying

As a result, in almost all levels of modern no longer made; instead, the malfunctioning

everything else in the process. electronics, actual repairs are circuit

board

is

pulled out and replaced with another board.

There is very little that you can do to repair failures on these boards, except purchase a few junker units that are the exact same model number as the unit that you own, isolate the problem, and interchange the failed board with one that will work. This is a great possibility, but chances are that you will not find a number of broken-down units that are exactly the same as yours. If you do find a number of these units in an unworking condition, chances are that you picked a poor model and you might be better off dumping yours than trying to repair a cheaply designed piece of electronics.

Most auto audio components are built using the slide-in board method, except for dedicated power amplifiers. Dedicated power amplifiers, especially the highquality American-made models, usually use large, heavy components soldered onto thick circuit boards. These amplifiers could be repaired, but they usually don't break down unless they have been mistreated. Even then, it is usually the power transistors (usually field-effect transistors) that go through meltdown. you can obtain a repair manual from the manufacturer, then you will have a better opportunity to repair your equipment; however, you probably will not be lucky enough to obtain the manual. Unfortunately, most companies only distribute this information to their authorized dealers, which forces nearly everyone to go to these dealers for repairs, or forces you to buy a new unit. In the 1950s and 1960s, a number of American electronics companies provided extensive support for their products with descriptive lists of components, test-point information, troubleshooting information and tips, If

much

286

racking

and the

like.

dow

Everything has changed with the advent of the twenty-first

century, and you are lucky

if

you can get any

free information about

any

electronic gear. is primarily intended for people who have anywhere from no experience to intermediate experience with car stereo systems. It is not a technician-level book; that is. it's for consumers, not electronics enthusiasts

This book

or repair technicians. So don't expect to be able to just flip to this chapter and use it to discover that voltage regulator Q86 is blown in your particular head unit and that you should replace it with a VR86A. Information of this nature would easily fill a very large book on its own. and someday I'm sure that it will. Instead, this chapter covers a few of the troubleshooting and repairing basics that are relatively easy for the beginner to perform and don't require the use of expensive test equipment.

down

Tracking

the problem

if you have no intentions of repairing your own equipment, it is important to search out the problem and tell the repair tech where the problem is and what is occurring. This will help the technician find the

Even

problem

One

in less

time and

it

could save you

some money.

episode of "60 Minutes" several years ago featured a segment that dealt

with the honesty of various electronics repair shops. a

VCR

with a simple problem

(I

They had

a

woman

believe that the drive belt might have

take

been

electronics repair shops in one city. Several of the parts were marked with an ultraviolet pen. The end result of the study was that most of the shops were not honest. Some shops claimed that parts were replaced that weren't; others claimed that they had performed repairs that off) into different

hadn't been done.

Hopefully the car audio shops in your area are much more reputable than would like to think that most in the "60 Minutes" study.

those that were

people

I

who make

customers, but

a career of car audio would be above

this is

not a perfect world. Even

if

scamming

their

car stereo installation and

most honest business on the face of the Earth, there be a few dishonest people out there. With this in mind, don't torture your repair technician with accusations; there's no need to ruin his or her day. Conversely, directly complimenting the shop manager and the repair would be the

would

still

repair technician after a successful repair might yield

some

nice dividends

287

Repairing car audio systems

when something

else malfunctions or

you want

to ask

some questions

regarding a do-it-yourself effort.

You should always be Nothing

subject.

will

as informed

and knowledgeable as possible on the on a repair like knowing what

deter getting ripped off

has failed where and being able to talk about

it

with a repair technician.

Determining faults in a system is a matter of taking educated guesses and almost randomly substituting other components for testing purposes: speakers, cables, wires, transmitters, and the like. The rationale is that if one part isn't working, you will be able find that problem by substituting different components one at a time until the system works. From this point, if the problem is in a complicated component, such as a head unit or an amplifier, you might not be able to narrow it down further without using a multimeter, a signal generator, and an oscilloscope, so you might be stuck at this point if you don't have this equipment. But you should always

problem

first

check the wiring

in the

(and possibly over the whole system,

is

if

area where you think the

you

fail

to locate the trouble).

Faulty wiring or connections will void the entire troubleshooting process

if

you

don't immediately check these possibilities. Also, car audio wiring problems

normally consist of

"is

it

connected or

isn't it?"

By

finding the faulty connection

or wire, you have just saved yourself a trip to the repair shop.

Check the wires by jiggling them and disconnecting/reconnecting them to the power distribution blocks. Beware of disconnecting the wires to the speakers whiie running the system at a high power level; you can cause severe damage to an amplifier if you run it in a no-load condition. The excessive power levels would

just "sit" at

the high-power outputs, which would overheat and fry the

If you have an amplified head unit, this can be especially dangerous because you would lose your amplifier and head

output field-effect transistors (FETs). unit in

one

shot.

example, your system does not work and no sound is reaching the Have you ever had any problems with it? Have you recently added any components that could have created problems with your system? If so, check out the wiring around this component. Next, check for commonsense things that you might have missed. Are the units turned on? Did you forget to plug in any audio cables when installing or rearranging the system? If,

for

speakers, check the wiring.

If

these problems aren't applicable, check the displays and power-on

indicators

288

on the various components.

If

you aren't getting any sound, does

KlBiElMllilBBifl the head unit even turn on?

If not. you should check the connections to the and also check the fuses. If everything else checks out OK and the other components in the car work, but the head unit doesn't, then it is probably safe to pull out the head unit and either check it in another car or have it checked at a car stereo repair shop.

head

unit

Of course, these tracing examples could be drawn out for 101 different minor problems. Rather than delve into all of these problems, which you probably won't ever encounter, and bore you to tears

book covers a few

in

the process, this

basics.

Organizing your work The procedures

to disassemble car audio electronic

equipment are very

complicated, and you must be very careful or you might wind up with a few

As you disassemble the electronic components, don't just pile. Write down the parts that you have removed and either put them in labeled sandwich bags or in small containers. You should even draw a diagram of the assembly/disassembly procedures so that you can "extra parts."

dump

out parts in a

reassemble your equipment and prevent your projects from remaining hopelessly disassembled. (Too many times have torn apart different I

would know for sure how to put the parts back together. Before long, it seemed that had the entire project into hundreds of only remembered how to fix half of the parts in the proper little pieces, and

components and

I

felt

that

I

I

I

location.)

Safety procedures Safety procedures are never fun because they slow

down your

progress.

I

guess I'm just too impatient for safety rules, but it seems as though it takes several catastrophes before get the hint that should be more careful. After a few traumatic experiences, my techniques improve. Fortunately. have grabbed the I've never come close to electrocuting myself, but I

I

I

off avoiding

them //

wrong end

me, you will be better unnecessary mistakes by reading about them than by doing

soldering iron by the

a few times! Believe

yourself!

you are not a technician, or

if

you have very

little

or no experience with

repairing electronic equipment, stay out of it! If you want to learn about repairing equipment, read some books that are dedicated to the topic of

289

Repairing car audio systems

and buy some inexpensive nonfunctioning equipment to experiment of the worst things that you could do is try to repair an expensive piece of equipment (such as a $600 head unit) with minor problems, cause more damage to it, and not have enough money to replace it. repairs

One

with.

you have had some experience working on electronics gear and feel in it, be careful, and connect the power only when taking measurements at the manufacturer's listed test points. When testing and taking measurements on the unit, it is much better to pull the unit out of the car, take it to your work area inside, and connect it to a regulated 12-V power supply that generates enough amperage to match the amperage demands of the unit. This method provides enough space and light to work, If

comfortable

rather than trying to solder upside flashlight in

electronics

your teeth.

workbench

It is

that

is

down on

the floor of the car with a

you have an open work area, such as an clean, stocked with parts, and well lit.

best

if

Be

sure to check for any manufacturer's warranties that you might void by removing the case and digging around inside. For the most part, if you remove the case o' any electronic component, you will void the warranty. Considering that you probably will not be digging around in your new $300 amplifier unless it has malfunctioned, voiding the warranty is bad news.

Electrocution and electrical shocks The

following section

is

alternators;

when working with amplifiers, when working with vehicle batteries and

only a concern

amplified head units, and possibly

no other auto audio components

unamplified head units,

etc.)

(equalizers.

CD

changers,

contain high-powered components. Always be

when working with electronics; there is always the possibility that you make the big mistake and be electrocuted. Several times have heard

careful

could

I

people say that they didn't have to worry about car electronics because only 12 volts, and 12 volts isn't dangerous. This simply isn't true. Any voltage can be dangerous, depending on the amount of current that is flowing.

Remember

the equation for power:

P= where:

P £

the

is

/ is

power

in

watts

the current in amperes

is

290

the voltage in volts

IE

it

was

Safety y procedures

1UUUUU1

If the car is putting out 12 V (usually, it varies between 11.8 and 14.0 V. depending on whether the car is running, etc.) and the amplifier is outputting in bridged mono mode, then: 250

W

250 = /x 12 = 25Q 12

/

/

However, efficiency,

this

= 20.83 amperes

equation only applies

which

is

if

the amplifier

is

operating at 100 percent

not possible. Chances are that the amplifier

percent operating efficiency, for example. With

this

is

closer to

50

being the case:

/= 20.83x2 /

= 41.66 amperes

Although 12 V is a relatively low voltage. 41.66 A is a huge amperage. You might also have heard the old electronics adage "it's not the voltage, it's the

amperage

that will get you." That's not entirely the case;

that might seriously injure or

kill

remember not

amperage.

to neglect the

you.

Still,

the adage

is

it's

the total

good way

a

Part of the reason for ignoring the dangers of 12-Vdc electricity direct current

is

less likely to

is

power

to

because

stop a heart than a 60-Hz alternating current

waveform. So your heart is much more touchy when dealing with standard house electricity than when with a car's power system. It

is still

possible to be electrocuted with 12 V, particularly

if

you are

well-

you are making a strong contact with the electricity (such as if your skin is wet or if it is entering through a cut). To prevent being grounded, don't stand in water, wear rubber-soled athletic shoes and stand on

grounded and

if

a rubber mat,

if

possible. Electricity always takes the shortest path with the

ground. So if you get shocked, you are actually a giant you are grounded through a puddle on the floor, you are a giant conductor. From a safety standpoint, you are much safer being a giant resistor; however, you are much safer, and happier, not being an electrical least resistance to resistor, but

if

component

at

all!

Because of the shortest-path-to-ground rule, it is best to avoid having grounding in a path that leads through the heart. For this reason, one commonly used rule in electronics is to work with the left hand in a pants pocket; thus, if you get shocked with a great amount of power, the electricity electricity

291

Repairing car audio systems

will

not pass through your heart, and you won't get

effective theory,

hand

in

except for one hangup;

it's

really

killed. It's

a simple and

tough to work with one

your pants pocket. After years of working with your hand

in

your

pants pocket, you probably won't get electrocuted, but your scarred right hand

and mangled projects

will testify

as to the clumsiness of the arrangement.

As

stated previously, be sure to unplug the unit that you are checking (unless you are taking measurements at various test points) so that you don't cause yourself bodily harm. And remember from the operational theory of stiffening

capacitors that capacitors store electricity until that charge

charge doesn't quickly dissipate while

an amplifier weeks or months still pack a wallop.

into

it

later

sits in

and

is

dissipated. This

a circuit; you could easily dig

find out that the heavy-duty

capacitors

Usually, for smaller discharging operations, the standard

method

is

to cross the

leads of the capacitor with a large plastic-handle screwdriver; however, to

prevent the possibility of having a charge jump over the shaft of the screwdriver

and

jolt

clip.

Be

you,

it

is

best to attach the screwdriver shaft to ground via an alligator

sure to discharge each large capacitor several times because

most

some electricity even after you have discharged them the first time. For a more scientific discharge method, cross the leads with a resistor of a value that has been recommended by the manufacturer. capacitors

will

still

store

Safety with electrostatics To protect

equipment from electrostatic discharges (also known as you must take almost the opposite mindset and approach than you did with protecting yourself against dangerous voltages. That doesn't mean that you should stand in a puddle of water while groping the insides of a plugged-in cassette head unit, but it is somewhat different. electronic

static electricity;),

Many of today's microelectronic components are intended to handle only minuscule amounts of power. Because of the need for miniaturization in mobile electronics, it is better for the parts to be used closer to the damage tolerances than to be forced to build the piece of audio equipment into a

much

larger enclosure.

levels of electricity that

anything

just

As

a result,

it

is

very easy to

we would have never

damage equipment

with

considered to be harmful to

one or two decades ago.

However, with modern integrated circuits, even a small blast of static can melt a tiny hole through the package and destroy one of the microscopic components or interconnecting wires. These blasts of static

electricity

292

impair the performance of the integrated might not seem like much, but this destructive static electricity is the very same as that which is discharged from your body. Just wearing tennis shoes and walking across carpeting on a dry day will cause an electrostatic charge that is easily powerful enough to destroy a typical integrated circuit. According to an article in Electronic Servicing and Technology, one person (depending on the clothing and other environmental conditions) can build up a charge of static electricity that exceeds 35.000 volts! electricity will either destroy or circuit.

It

As you can see. it is very difficult to handle integrated circuits without damaging or destroying them. To prevent damage, it is important to wear a grounded wrist strap, which is a conductive strap that is connected to ground via a wire. This method is effective because the ground bleeds off the than allowing it to suddenly build up), then releases through the conductive strap to ground. electricity (rather

it

you are working on complicated integrated-circuit-laden units, such as units, be sure to use grounded wrist straps; otherwise, even getting too close to the unit (without touching it) could cause your body to discharge electricity through it and damage components.

So

if

head

%) Repairing speakers Over the

years.

I

have heard stories about

Davies slashed the speakers

how

the Kinks' guitarist

in his guitar amplifier

Dave

with a razor blade, then

taped the shreds back together with cellophane tape. And that's the rumor behind the prefuzz box guitar distortion that helped make "You Really Got

Me"

a classic. (The Kinks have never

chat, so I've never

been able to

dropped by

my house

for a pizza

and a

validate the truth in this story.)

remains that a torn speaker cone will significantly alter the And although that tinny guitar sound rocked a generation in entire song through a torn speaker will ruin the sound of an 1964. running

But the

fact

speaker's sound.

your system.

According to the fundamentals of electronic audio, the speaker cone must rapidly push in and out, like a piston in an engine. Obviously, a hole in that audio piston will destroy its efficiency, will alter its resonant frequency, and will thus make the speaker reproduce some frequencies less effectively.

293

Repairing car audio systems

Never continue to use a speaker with a torn speaker cone, if it has any value That pistonlike action will only cause the speaker to tear even further if you continue to use it. Pull the speaker out immediately and either replace it, stop using your system until you replace it. or disconnect the speaker wires that you would have left hanging. to you.

The options

you are

that

left

with are to either buy a

speaker or to repair the torn speaker. By

buy a speaker, so

it's

this point,

new replacement

you already know how

to

time to repair one instead.

Punctures, tears, and holes Speaker cones can be ripped they

still

somewhat

require

in

a variety of ways, but any

way you

slice

'em,

similar repairs. Small punctures in the speaker

cone are the easiest type of cone problem to repair. Simple, clean tears can be repaired easier than holes and "rough"' tears that branch out from the main tear line (Fig. 11-1).

Figure

11-1

A

torn speaker cone.

Large holes and rough tears all require special treatment, and even after a repair job, you still might notice somewhat of a difference in the sound

good

and the other undamaged speakers. You will probably if you make the major repairs on woofers or subwoofers because the cone is much larger and thicker and the resonant

quality

between

it

notice less of a difference

frequency If

is

low.

you are repairing a small puncture

in

a paper or paper-composition

speaker, try pushing the displaced paper from the backside.

If you can pull dabbing some clear fingernail polish on both sides of the puncture to hold the tiny fragments of cone material back together. If the punctured speaker cone is clear poly or something similar, try

this

paper back together,

294

try

Repairing speakers

creasing the displaced material back toward the center of the hole, and dab either clear fingernail polish or

model airplane glue on both

sides of

and over

the puncture.

If

you have a midrange or tweeter with a

light tear in the

small piece of clean, unwrinkled tissue paper.

Then

cone, cut out a

lightly

cover one side of

the paper with either clear fingernail polish or a thin, heavy-duty, general-

purpose adhesive. Be sure to cover

all

of the edges with the adhesive. After

the adhesive has dried thoroughly, apply a thin coat of clear nail polish over

the edges or else they

resonate. Another

will

be

much more

good method

likely to

peel and potentially

to avoid peeling edges

corners of the tissue-paper patch

is

to

round the

(Fig. 11-2).

Figure

Repairing a torn speaker cone with tissue paper and glue.

Repairing a large speaker tear or hole

will

probably require more ingenuity

and skill on your part. One of the best methods to repair paper speaker cones with large tears is to pull a few old speakers out of your junk box. Unfortunately, most people don't have an electronics junk box so that they can pull out parts for important repairs or fun projects. If you have an old, dead, or cheap speaker laying around the house somewhere, this is the time to sacrifice it for the good of your audio system.

295

11-2

Repairing car audio systems

arrangement would be the same as in the last case: cut out a speaker cone that is large enough to patch over the tear in the good speaker. When you cut the patch out, make sure that it will perfectly adhere to the surface of the cone that you are repairing (for example, you wouldn't use a ribbed cone patch over a tear on a smooth speaker cone). Then apply and cover the patch, as was discussed in the In this case, the

piece of the

sacrificial

previous paragraph.

where the speaker has a large tear or a hole, and if the tear in is in an area that is not smooth, such as a ribbed section, use a tissue-paper patch instead of one from a cannibalized speaker. Be sure to either use another tissue paper patch on the other side from the one that you made, or cover the torn area with a light coat of clear nail polish to seal and protect the speaker cone patch. In this case,

the speaker cone

If you have a large tear or hole in a clear poly speaker, you must have really abused it! Regardless, try to seal it up with a seam of model airplane glue, if possible. If you can't make both sides reach, then get a sheet of the thin plastic that is used to make transparencies for college lectures, group singing, and the like. Just cut a patch out of this material using the methods described in the previous paragraphs. Then use model airplane glue or another type of plastic adhesive to hold the patch/speaker cone together. As in the other cases, be sure to seal up the rough edges with a hard, clear adhesive.

Repair techniques change

woofers and subwoofers, which and heavier speaker cones. Because woofers and subwoofers are intended only to reproduce low frequencies, you can get away with using a relatively heavy patch without causing much of a difference in sound quality. Because of the woofer movement, you should always use a patch to prevent further damage, whether or not the tear is "clean" or not. The cannibalized speaker patch is a good method, whether or not this paper or paper-compound speaker material is heavy or not. Another possibility is a patch made from a paper grocery bag! It's ugly, but it works. generally must have

much

slightly for

larger

Ugly patched speakers Because

I

have

or electronic, is

solid.

As

I

little

in

your car?

concern for the beauty and

don't really care

how

ugly

it

styling of anything technical

looks as long as

it

works well and

a result, ugly, repaired speakers don't really bother me, as long as

OK. do, however, understand that some people might not want have subwoofers that have been patched with paper grocery bags in the rear deck of their hot new car.

they sound to

296

I

Repairing speakers

One way around

this is to tightly

so that the speakers transparent, which

will

not be

means

that

cover the top of the speaker with

visible. Grille cloth is it

grille cloth

acoustically

won't "soak up" the sound or "deaden"

certain frequencies. Parts Express currently sells three different colors of grille

and Scosche offers 11 different colors to match the interior of your With a bit of creativity, you can do a custom installation that looks like was performed at the factory. cloth, car.

(J) Deteriorating

it

surrounds

Aside from dampness, one of the most damaging conditions encountered

in

from the sun. Speaker cones have to pound in and out as your audio system is in use: however, the cones remain generally solid, and it is the speaker's surround that must continuously flex in and out. Surrounds are typically made of paper, cloth, and poly foam. Some of the synthetic materials that were used for surrounds in the mid-1980s have been gradually breaking down in the sunlight. One friend has a car with speakers like this, and the surrounds have developed cracks and thin tears in the foam material (Fig. 11-3). These speakers need

the car stereo environment

is

that of ultraviolet rays

to be replaced.

Figure

Surrounds that have deteriorated after too many years of

ultraviolet light

exposure.

297

11-3

Repairing car audio systems

Rather than pitch out your once-prized speakers with the dry-rotting surrounds, you might consider repairing them. This time

I

don't

mean

pulling

out the grocery bags, blown speakers, tissue paper, and clear fingernail polish. Parts Express currently offers speaker surround repair kits to save your speakers. You must remove the old surrounds from the speaker and install the new surrounds with a high-strength adhesive that is included with

the kit. Unfortunately, the kits are only available for round speakers that are 8" (20.32 cm) or larger in diameter. So you can save your woofers and

subwoofers. which are generally

midranges. but

kiss the

much more expensive than

tweeters and

other speakers good-bye.

Equalizers Most equalizers consist primarily

of variable potentiometers that are used to

adjust the strength of the various frequency ranges. built-in amplifiers

The

Many

equalizers also have

or preamplifiers to boost the levels.

three basic types of separate equalizers are dash-mounted units that also

contain amplifiers, active dash-mounted units (they contain preamplifiers), and active floor- or

anywhere from 3

The

floor- or

units. The dash-mounted units are generally some combination of slider potentiometers, usually

trunk-mounted

those that contain

to 12. either per channel or for both channels (mono).

trunk-mounted models nearly always have dial-type knob

potentiometers instead of the sliding faders. The difference

mounted

is

that the dash-

compensate for or alter the sound of the source. The floor- or trunk-mounted units, on the other hand, are intended only to be occasionally adjusted to compensate for or alter the sound of the system.

As

units are intended to be adjusted frequently to

far as repairs are

concerned, the only weak areas

in

a good-quality

dirt, grease, and and standard knob-type potentiometers will sometimes become scratchy-sounding or intermittent. Spray a cleaner chemical, such as Jet-Lube Terminal contact cleaner, into the potentiometers, and slide them back and forth to work the chemicals into the contacts. Once you have worked the fluid into the contacts, check to see if the potentiometers work any better. If the equalizer is more than 10 years old. some of the potentiometers might be wearing out and need to be replaced, particularly if they were of a lesser-

equalizer are the potentiometers. After several years of dust. use, the slider

quality manufacture.

298

Head

Replacing a single

slider

potentiometer can be tough because

it

units

must match

the original one in value and must perfectly match the size of the others. For

manual for part numbers page through electronics parts catalogs and check the values you find an exact replacement.

best results, either consult the manufacturer or the (if

available) or

and

sizes until

Head

units

Cassette head units often require

more maintenance and

repairs than

any

other piece of car audio equipment because they have more moving parts

and have

to

make

contact with dirty materials.

Cassette decks common

deck to croak, begin sounding bassy, slow down, is when you question why you ever thought that deck sounded great, and you start looking for a new model. Meanwhile, the forlorn deck is sold off cheap or is simply thrown away. It is

for a cassette

or eat tapes after a few years of use. which

Most problems with cassette decks are relatively minor and inexpensive to remedy, so it's a real shame when one of these head units gets pitched. Because of limitations in the scope and size of this book, it is somewhat limited in its troubleshooting and repairing information. For more than 400 pages of information on the subject, read Troubleshooting & Repairing Audio & Video Cassette Players & Recorders by Homer L. Davidson.

Muffled audio, or tapes are eaten The most common problems

with cassette head units are that the audio

is

muffled or that the tapes get eaten by the playback mechanism. There's nothing worse than having your brand-new $10.99 cassette by the Paul

Johnson Trio eaten,

especially

when

this

problem has been occurring with You could even make a fist

increasing regularity over the past few months.

and scream "When will this lust for ferric oxide coated tape ever end?!" But the wanton cassette violence won't end until you stop using the deck, unless you choose a route of maintenance. Although muffled audio and problems with the playback mechanism seem thoroughly unrelated, both can be different symptoms of the same problem. Of course, all standard cassettes consist of a mixed magnetic substance (usually ferric oxide, chromium oxide, or metal oxide) that has been very

299

Repairing car audio system

onto a synthetic tape. After some wear, these oxides

thinly coated

will

up a

light

coating of residue across the parts of the deck that

rub against the tape.

The

residue resembles

eventually build

exactly that

most accurate sound reproduction

The

best

some form

—foreign matter that must be removed

way

to take care of these

in

of

swab or a cleaning

is

an easy

stick into

it is

problems

is

to clean everything that

task. Just

open the

home

is

in

audio

cassette door, dip a cotton

rubbing alcohol, and carefully clean the erase

head, the tape head, the pinch

roller,

Even though an auto cassette head

much more

and

possible.

the path of the tape with rubbing alcohol. With a standard cassette deck, this

dirt,

order to preserve the

your way

and the capstan.

unit doesn't

have an erase head,

it

is still

through the tiny slot to clean the tape head, capstan, and especially the pinch roller. To reach back to these parts,

you

difficult to dig

in

need to use long cleaning sticks instead of cotton swabs. Because of slot, you will probably need to have sunlight directly behind you or a flashlight shining into the hole. If you don't know what the tape head, capstan, and pinch roller look like, see Fig. 11-4. All of these parts look quite similar in head units that have been made by various manufacturers. will

the small

Figure

11-4

Capstan Roller

pinch

The head, capstan, cassette head unit.

300

and take-up

reel

of a standard

The capstan and tape head should be easy to clean; just rub them with the dipped cleaning sticks a few times. The pinch roller is more difficult because it is rubber, and you must rub it hard to remove the tape residue. After the tape deck has been used for some time without being cleaned, you will notice

a stripe of tape residue running through the middle of the pinch

roller.

When

you clean the pinch roller, you must turn it as you rub it clean. Otherwise, only one portion of the pinch roller will be clean. By the time you are finished, you should barely be able to see any of the residue stripe. is a common part of audio maintenance, and it is you clean the cassette heads for every 40 hours of use, although few people adhere to this advice. A clean playback mechanism is essential for the head unit to perform up to its capabilities. When worked a radio station, we were required to clean the heads on the cassette decks and open-reel decks at every use. have to admit that have slacked off

Cleaning the heads

recommended

that

I

I

I

considerably since that time, but a clean playback to achieve

I

good

at

mechanism

is still

essential

cassette performance.

recently talked to a friend about the

playback mechanism.

He

said

"Why

wonders and

difficulties of

cleaning the

don't you just use a head-cleaner

cassette?" Some head cleaner cassettes use abrasive tape to clean the heads. These abrasives can wear out the heads if the cleaning cassette is used too often. Frankly, after paying several hundred dollars for a new cassette unit. would much rather pull out the rubbing alcohol and the cotton swabs than I

risk the life of that

precious magnetic head. Also,

some head-cleaner

cassettes only clean the heads, not the capstan or the pinch

which

really

cassette,

make

sure that

it is

capstan, and pinch roller

roller,

both of

you are looking for a cleaner nonabrasive and that it cleans the heads,

should be cleaned regularly.

If

(Fig. 11-5).

Figure

Compact

disc laser lens

cleaner (left) and cassette head cleaner (right).

301

1 1

-5

epairing car audio systems

If the head unit sounds muffled, a dirty tape head is probably the culprit. If you clean it, but a few stubborn dirt spots remain, try rubbing it very gently with a soft, clean, and unused pencil eraser. Don't use older or dirty erasers because they can leave difficult-to-remove smudges. Don't use pen erasers because they can scratch the fragile tape head.

the primary problem is tapes being eaten, also look around the capstan for any remaining pieces of tape. These pieces can cause further problems with head units getting the munchies. Little pieces of tape are easy to remove from the capstans of home cassette decks because you can easily reach inside. With auto decks, however, all you can do is take apart the case to reach inside, or try to reach the capstan from the outside with a pair of tweezers. If

the sound is still too muffled, try cleaning the heads again. If you still don't have any luck, try using a head demagnetizer, which should cost about $5 to $10, or borrow one from someone. Tape heads become magnetized when they are too close to a powerful speaker or some other magnetic field. I doubt that you'll be setting any 18" subwoofers on the dashboard, but demagnetizing the heads is worth a shot anyway. If

To demagnetize the heads with a hand-held unit, plug in the head demagnetizer, and turn it on. Put the end of the operating demagnetizer in the cassette slot and position it close to the heads, then in one motion pull the demagnetizer out and draw away while the demagnetizer is still operating. If

you turn

off the

demagnetizer while

cassette player, the heads will

it is

close to the heads or inside

become magnetized,

they were originally. Because of the

difficulty in

possibly even worse than

accessing the cassette

chamber and heads of any auto head unit, cassette-shaped demagnetizers are available that you can just plug into the cassette slot and demagnetize the heads, which is a much more convenient method than using a hand-held unit. you have

and the sound

too muffled, check the and blown the tweeters in your system. Try listening to the tweeters where they are. If you are sure that they are working (i.e., they are producing sound), then leave them alone and move on to the other speakers. If you aren't sure about the tweeters, try disconnecting any other speakers (such as subwoofers) in the system. If you still aren't sure if the problem lies with the head unit or the speakers, attach the car speakers to your home-stereo, which should provide a reference concerning the sound of the car speakers, although they will sound different in the much larger setting. If the speakers don't have enclosures, they will sound entirely different than they would installed in your car. If

speakers.

302

tried everything

It is

is still

possible that you have overdriven

ead units

still check out OK. chances are that the heads are wearing At this point, it is best to take the deck to a reputable auto audio repair shop to have it inspected. Heads and the labor for head replacement can be If

the speakers

out.

if this is indeed the problem, make sure that you get a quote so that you can either get an estimate from another shop or you can decide whether the replacement is worth the money.

quite expensive, so

Wrong

or variable tape speed

The most common cause of problems with the tape speed is the drive belts. The drive belts are fine, black, rubber belts that look much like thin rubber bands. They drive the various moving parts in the cassette deck, such as the capstan. If

the head unit

head

unit

is

is

running slow, chances are that the

slipped around the flange of one of the pulleys. at variable speeds, the belt

all

contact with

It

is

is

you have

If

too loose.

the head unit

is

some

If

the

is

it is

lightweight

playing back

loose or oil

or grease.

head unit, open up head unit out of the drive assembly and replace to pull out the

bad enough to

cars, but tearing apart the unit to find

the old belts First

in

of the conditions, the only recourse

the case, and replace the belts.

most

is

might be slipping, either because

because the pulleys have gotten In

belt

playing back at faster-than-normal speeds, the belt might have

pull a

a real annoyance. to try to find the appropriate belt for your

the owner's manual to see

if

a part

number

is

listed for

head

unit.

Check

the problematic belt.

that it wont be listed, so you will have to look elsewhere. Call a few auto audio installation/repair shops in the area to see if they can either provide the part or at least give you the part number: otherwise, check with some of the electronics mail-order companies that handle parts for various audio equipment. Even if the exact part number is not available for your particular model, the sales representative might be able to provide a replacement belt that has the same dimensions. If you have looked everywhere, but you still can't find a belt with the right dimensions, you could try buying a smaller belt and stretching it enough that it will fit and run properly. It's not the best solution, but it beats buying a new head unit.

Chances are

But

how much

tension

is

appropriate for the belts? You can skip

this

question

you have a strain gauge that measures the amount of tension on a belt and you have managed to obtain the privy information on belt tension from the manufacturer. Of course, few people have a strain gauge, which would be if

impractical outside of a small electronics repair business.

303

/£

Repairing car audio systems

Unfortunately, you might have let

alone being able to

some problems

test their

just

accessing the drive

tension at your leisure.

cassette deck in Fig. 11-6 are buried underneath the

playback assembly.

In

order to perform this

The

belts,

drive belts for the

motor and the cassette simple maintenance

common,

you must pull the deck out of the car, open up the top panel of the unscrew the cabling, unscrew all of the screws on the underside, disconnect the front panel, and pull everything out of the box. If you were intent on replacing the belts on this model, chances are that you would break something else while you were just trying to access the drive belts. task,

cabinet,

Figure

11-6

The belts are buried under several layers of electronics and mechanical parts in this

head

unit.

Other problems can result when fitting those thin belts through tiny little nooks and around a few pulleys until they fit properly. Oddly enough. have never read about anyone who seemed to think that this task was difficult. Troubleshooting and repair books just say something like "replace the belts and move on to .."I think that replacing the belts on an auto cassette deck I

.

often

more akin

.

you are seated in a and thread behind your back and underneath the chair's seat! With some patience and perhaps an instrument (such as a ballpoint pen) to help move the belt into place, you can replace the belts. Do not try this when you are in a bad mood or feeling impatient!

is

to trying to thread a needle while

folding chair with your hands, needle,

304

ead units

Compact

disc players

Like all head units, compact disc players are very complicated units packed with tiny components, some of which are sensitive to static electricity; thus,

these units are very

will

properly. Troubleshooting information in this

CD

but

difficult to repair,

perform some easy maintenance tasks that

keep your

book

is

it

is fairly

that are

easy to

discs running

limited; for

much more

head unit information (nearly 500 pages worth), read Troubleshooting Repairing Compact Disc Players 2nd Edition by Homer L. Davidson.

—

&

Safety

Compact disc players of all sorts can be very dangerous to work on. both because of your own safety and the safety of the player. The compact disc player operates somewhat like a record player, but rather than using a needle to pick

up vibrations from the

You can

disable the

front of the

beam

disc,

mechanism

a laser

beam

is

used to read the

that turns off the laser

for a long time.

You won't suddenly

disc.

and put your hand

in

cut through your hand,

any pain. For that matter, you won't even feel anything. was going to be like the laser in "Goldfinger." The CD's laser is not totally harmless because it can damage your eyes if you look at it. Don't look at it! And to keep your eyes safe when working on a powered disc player, place a CD in the machine if you need to poke around inside. The CD will cover the beam. Obviously, your eyes are very important, so be careful when working inside of compact disc players.

and you won't

feel

And you thought

Compact

it

disc players also present a potential for self-destruction. Recall

the safety section at the beginning of this chapter that

compact

from

disc players

are more prone to destruction from static discharges from your body. When working on compact disc players, be sure to use a grounded wrist-strap and ground the soldering iron to prevent dangerous levels of static electricity from damaging the fragile integrated circuits. Some references also state that you should use grounded electrically conductive mats under yourself and the compact disc player that you are working on.

The skipping head The most common

unit

among auto audio enthusiasts is that compact disc Some units skip constantly, some only skip when is

gripe

players skip too much.

it

were fine initially, but gradually began to skip more and more until they were virtually unusable. Although have had a blast making Neil Diamond discs skip so that he sounds like a rapper, skipping cold, or hot, or rainy; others

I

isn't

much

fun otherwise.

305

Repairing car audio system

many compact

more prone to skipping than mechanisms have been built into these players. So if you buy an older, used model, you will probably have more problems with skipping than if you purchase one that has been made more recently. Although have heard a number of good and bad comments about models from different companies, the two companies that have been consistently praised for the quality of their compact disc players are Alpine and Clarion. Owners of players from these two companies consistently speak

The

fact

others.

is

that

Over the

disc players are

years, better antiskipping

I

of

how

they rarely skip.

Other than the skipping problems that are inherent in the design of compact most common skipping problems are caused by poor installations. The problem is that most of these head units are installed well, but not vibration-proof. Vehicle vibrations that are transferred to the head unit will cause the compact discs to skip. Correct this problem by tightening up the mounting brackets in the dashboard and mounting the unit more solidly. Make sure that the unit will not wiggle or vibrate within the mounting when the vehicle is moving. If you have small cracks, you can even try jamming shims around the edges of the mounting to tighten it up further. The shims won't look pretty, but who is listening to shims? disc players, the

A

tight

suspension and consequential rough ride might cause skipping even

the mounting

is

ungiving.

The bounces

will

if

probably be too rough for the

If this is the case, consider mounting the head unit on a layer of which might successfully absorb the shocks from the bumps in the road. Like in any other arrangement, you still must mount the head unit solidly into the dashboard; the rubber layer is not a viable replacement for a solid mounting.

machine. rubber,

The only other

you can make to prevent your from skipping is to alter the suspension in the vehicle so that everything has a smoother ride. On the other hand, the skipping could be caused by other problems that are discussed in the next section.

compact

vibration-related alteration that

disc player

Cleaning the laser optics assembly Aside from a loose head unit or tight suspension, one of the worst causes of skipping is a dirty or dusty laser optics assembly. Little effort is required to clean the laser optics assembly; the task in a cassette

alcohol, dip

assembly.

306

If

deck. Just get

is

very similar to cleaning the heads

some cotton swabs and a

bottle of rubbing

one of the swabs in alcohol, and rub it over the glass laser optics you see other wads of dust inside, clean those up, too, or use a

compact-disc-player cleaning laser optics

kit;

otherwise, the debris might shift toward the

assembly and cause even more skipping

later on.

you are using an in-dash CD head unit, as opposed to a portable CD player been wired to a cassette head unit, then you might have a few more problems cleaning the laser optics. If the head unit is older and you think that the laser optics might be dirty, then you will probably have to pull out the unit and remove the top cover to clean the laser optics. If you don't think If

that has

that this assembly

is

causing the problem, then don't bother tearing

everything apart for no reason. Because the disc entry slot on a head unit so small (which reduces exposure to foreign material), dirty optics are

more

of a

problem with portable

is

much

disc players than with auto units.

Check the source Although chances are that any CD skipping is caused by the head unit installation, it's worth checking the CDs. If problematic compact disc or discs have been scratched or are smudged or dirty, that might be causing the skips. Some people claim that if the discs are scratched, they rub nail polish remover over the scratches. haven't scratched any of my discs, so have not been forced to try this method. I

I

If

you

feel

uncomfortable using varnish remover on your precious audio, you CD Finishing System from Allsop. which is a

might want to check out the disc-scratch repair

directly

If

kit.

This

you can't find from Allsop. which

market, so

if

the discs are dirty, clean

as a

common

available

is

the only

it

in

is

listed in

kit

of this type that

I

have seen on the

a store, you can try writing for information the sources appendix.

them with a plastic-safe, nonabrasive cleaner, such Or try one of the CD optics cleaners that are

glass cleaner.

from a number of

different

companies.

Technical adjustments stated earlier, technical adjustments are well beyond the scope of this book, especially for compact disc players. For most work on CD players, an oscilloscope and other electronic test equipment are required. As a result, there is very little that a beginner is able to maintain or repair on a compact

As

disc player.

307

Repairing car audio systems

Dedicated amplifiers the nontechnician. There are no motors to maintain. Everything is entirely electrical, not mechanical. Because of the lack of moving parts, amplifiers rarely fail (unless they have been driven too hard) and as a result, the better manufacturers have warranties of several years on each amplifier. Normally when something goes wrong, the amplifier fails entirely, and if this happens, the chances are that you're stuck. You must take the amp to a factory service center because if you open up the amplifier to see what failed, the warranty will be voided.

Dedicated amplifiers are a

moving parts and no

difficult fix for

belts or

LED "on" indicator doesn't even check the fuse to make sure that it hasn't blown. If it has, replace only with a fuse of the same value and type. If you use any other value or type of fuse, you won't be able to get the amplifier running. If the fuse value is too low, it will blow. If the fuse value is too high, the electricity will be below the cutoff values of the fuse, but above the ratings of the parts inside. The "on" indicator will probably glow for a few seconds, and in the meantime, the components inside will be getting fried. If

the amplifier no longer operates and the

glow,

If

first

the amplifier won't turn on, but the fuse

is

fine,

check

all

of the

it

power

connections between the amplifier and the battery. Possibly a power

An

way to make sure that the amplifier is power leads with a voltohmmeter: a good digital meter can be bought for about $20 or $30. so watch for a sale and buy one for this and other electrical troubleshooting tasks. While you are connection came loose. receiving

power

is

easier

to check the

checking out the connections and the integrity of the wiring, also check under the dashboard to

make

If

the wiring

properly connected to the amplifier, yet you are that the amplifier has If

the "on" indicator

is

in working order; working order and is can't get it working, chances

sure that the car's fuses are

replace any fuses that have blown.

some

all

in

internal problems.

glowing, but there

and connections from the head

still

is

unit

is

no audio, check the audio

lines

through any other processing boxes to

Then make sure that any of these boxes are turned on and working properly. Check the volume controls on the processing boxes and

the amplifier.

the gain control

appropriate

308

on the amplifier to make sure that they are all set to an (See chapter 3 for more information on amplifier tuning.)

level.

your amplifier appears to be dead or not working properly and you plan to it in for repairs soon, wait a few days. In the interim, check everything over a few more times because you might discover something you missed the If

take

time,

first

When the

and you might think of

an amplifier

power

is

a simple

way

to correct the problem.

overdriven, overheats, and finally melts down, usually

amplifier blows out

Although sometimes a

fair

its

transistors in the final amplification stage.

number

components are destroyed along with fails. As a either severely damaged (many destroyed of

these transistors, at other times this output stage overheats, then result, a

blown amplifier

parts) or minorly

is

damaged

usually

(the final output transistors are destroyed), but

many power transistors are expensive, when you can pick up a few replacement pop them in place to replace the burned-out

usually not in between. Unfortunately,

so

it

is

a

somewhat

rare case

transistors for 50 Conclusion Although the electronics layperson is severely limited by what he or she can do to repair an auto audio system, it is possible to perform some simple maintenance and repair procedures that can save quite a bit of money and prolong the life of your system.

309

o Sources Computer BBSes and networks

Audio Amateur P.O. Box 576 Peterborough,

NH 03458

Audio Cool (206)

248-9453

Audio Projects (608)

Auto Sound & Security 774 S. Placentia Ave. Placentia,

CA 92670

836-9473 AUTOtronics

CrossOver (914)

BBS

253-4357

6420

Wilshire Blvd.

Los Angeles, (303)

CA 90048

447-9330

Internet/Usenet rec. audio, car

1040 MIDI & Music 732-4446

(604)

Magazines Audio 1633 Broadway New York. NY 10019

3!\

31 °

Car Audio and Electronics 21700 Oxnard St. Suite 1600 Woodland Hills, CA 91367 Car Stereo Review

Box 57307 CO 80322 (303) 447-9330

P.O.

Boulder.

Sources

Speaker Builder P.O.

American Bass

5242

Box 494

NH 03458

Peterborough.

Stereo Review

(717)

1633 Broadway New York. NY 10019

(800)

a/d/s Progress

Wilmington.

(313)

Way

MA

01887

(617)729-1140 (508) 658-8498

(fax)

Advent Mobiles

25

Tri-State Office Or.,

Lincolnshire. 1L

(800) (708)

(fax)

#400

826-4697 380-8890

(fax)

Amptech 2305 Montgomery St. Ft. Worth. TX 76107 (800) 364-9966 (800) 324-4405 (fax)

60069

284-7234 317-3826

Aiwa 35 Oxford

296-2213

American Terminal 48925 West Rd. Wixom. MI 48393

Manufacturers

One

Warrensville Center Rd.

Maple Heights. OH 44137 (216)475-9311

(fax)

Dr.

Apogee 3145 Donald Douglas Loop Santa Monica. CA 90405 (310)915-1000 (310)391-6262

S.

Moonachie. NJ 07074

289-2492 (212) 512-3710

Audio Connection

(800)

(fax)

Alphasonik 701 Heinz Ave.

7950

E. Redfield Rd.

Suite

130

Scottsdale.

CA 94710 548-4005 (510) 548-1478 (fax) Berkeley.

AZ 85260

(800)825-7311 (717) 296-2213

(fax)

(510)

Alpine

19145 Gramercy PI. Torrance. CA 90501 (310) 326-8000 (310) 782-0726 (fax) Altec Lansing

P.O Box 277 Milford.

PA 18337

258-3288 (717) 296-2213

AudioControl 22410 70th Ave. W. Mountlake Terrace. WA

775-8461 (206) 778-3166

98043

(206)

(fax)

Audio Gods 5101 Lankershim Blvd. North Hollywood, CA 91601

(818)509-8879 (818) 760-8484

(fax)

(800)

(fax)

311

Sources

Autotek

AudioLink

23241 LaPalmaAve. Yorba Linda, CA 92687 (800) 327-5905 (714) 692-0068 (fax)

Calle

Amanecer

#0

San Clemente, CA 92673 (714)498-2770 (714) 498-5112 (fax) Audiosource 1327 N. Carolan Ave. Burlingame, CA 94010

(415)348-8114 (415) 348-8083

(516)231-7750 (516) 231-7897

99

2630 Nova Dallas,

(fax)

(214) (214)

Dr.

TX 75229

484-8881 484-8819

BBE Sound

(fax)

Inc.

5500

Bolsa Ave.

Suite

245

(714)897-6766 (714) 895-6728

(fax)

(fax)

USA

B&G

(fax)

Mobile Concepts

Box 202902 Austin. TX 78720 (800) 874-8803 P.O.

NY 11001

865-5200 865-5209

(516)231-7750 (516) 231-7897

(fax)

(708)

Authorized Parts

Company

Boss/AVA 3628 E. Olympic

208 Berg

(708)

St.

60102 654-6464 658-0582 (fax)

Algonquin, IL

Los Angeles.

(800)

(213)

(708)

(213)

Autosound 2000

2563

NC 27215

570-0341 (919) 570-1268

(919)

312

(fax)

Blvd.

CA 90023

881-0838 881-0835

(fax)

Boston Acoustics

Eric Lane, Suite

Burlington,

CA 92649

Blaupunkt P.O. No. 4601 North Suburban, IL 60197

Tulip Ave.

Floral Park,

CA 94010

692-2444 (415) 692-2448 (415)

Huntington Beach,

Audiovox 150 Marcus Blvd. Hauppauge. NY 11788

Audison

Rd.

Avalanche

Audioquest

915

855 Cowan Burlingame.

D

70 Broadway Lynnfield,

MA

01940

592-9000 (617) 592-6148 (617)

(fax)

(fax)

Sources

Bostwick

Clif

125 Old Monroe Rd.

1602 Babcock

Suite

200

Designs

Costa Mesa.

GA 30622 543-9494 (706) 369-9519 (fax)

St.

CA 92627

845-7002 685-8547

Bogart.

(800)

(706)

(805)

Cadence 6519 Hwy. 9 N.

Coast Manufacturing Co. 200 Corporate Blvd. S. Yonkers. NY 10701

Howell.

(914)

(908)

(914)

(908)

NJ 07731 370-5400 370-5553 (fax)

376-1500 376-0400

(fax)

(fax)

Sun Electronics Inc. 1000 Brioso Dr. Costa Mesa. CA 92627 (800)678-1115 (714) 631-3709 (fax) Collins

Canton 915 Washington Ave. Minneapolis.

MN

333-1150 (612) 338-8129

55415

(612)

(fax)

Coustic

Case Logic 6303 Dry Creek Parkway Longmont. CO 80503

447-4848 (303) 530-3822

4260 Charter St. Vernon. CA 90058 (213) (213)

582-2832 582-4328

(fax)

(800)

(fax)

Consumer Electronics 13845 Artesia Blvd. Cerritos. CA 90701 (310) 926-9944 (310) 926-9269 (fax) (416) 673-3307 (Canada) Craig

Cerwin-Vega 55 E. Easy St. Simi Valley. (805)

CA 93065

584-9332

Clarion

661 W. Redondo Beach Gardena.

CA 90247

(310)327-9100 (310) 327-1999

Eric

(fax)

Lane

NC 27217 228-9749

Burlington.

(910)

Crazy Dog Beware! 9600 54th Ave. N. Minneapolis.

MN

328-0795 (612) 559-8412

55442

(800)

Clark Audio

2563C

Blvd.

(fax)

Custom Autosound 808 W. Vermont Ave. Anaheim. CA 92805 (714)535-1091 (714)533-0361 (fax)

313

Sources

dB Speakerworks 1430 Dalzell Shreveport, LA 71103 (318) 425-2525 (318) 227-8058 (fax)

Earthquake Sound Corp.

Death Sound

Eclipse

1960 Del Torrance. (310) (310)

Amo Blvd. CA 90501

328-4092 328-2303

350 Lang

Rd.

Burlingame.

CA 94010

344-5897 (415) 344-7233 (415)

19600

S.

(fax)

Vermont Ave.

CA 90502 233-2216 (310) 538-1272 (fax)

Torrance. (800)

(fax)

Denon Electronics 222 New Road Parsippany. NJ 07054 (201) 575-7810 (201) 808-1608 (fax)

Tallahassee.

Discwasher

ETI

46-23 Crane St. Long Island. NY 11101 (718)392-6442

7300 Somerset Blvd. Paramount. CA 90723

Eminent Technology 225 E. Palmer St.

FL 32301 575-5655 (904) 224-5999 (fax) (904)

(310) (310)

633-3987 633-1931

(fax)

Dr. Crankenstein

1536 Winchester Ave. 215 Ashland. KY 41101 (606) 325-7757 (606) 324-3987 (fax) Suite

Dynamic Control P.O. Box 15232 Hamilton. (513) (513)

OH

1048

Calle Las Trancas

Thousand Oaks, (805) 376-3541 (805) 376-3561

CA 91360 (fax)

Fultron

Box 177 Memphis. TN 38101 (901)525-5711 P.O.

45014

860-5094 860-5095

Eton

(fax)

(901)

525-7993

(fax)

Dynaudio

G&S

Box 44283 Madison. WI 53744 (608) 831-2990 (608) 831-3771 (fax)

26227 Research Rd. Hayward. CA 94545

P.O.

314

(510) (510)

783-4440 783-8444

(fax)

Harman Kardon 8400 Balboa Blvd. Northridge. CA 91325 (818) (818)

893-9992 894-1212

(fax)

Infinity

9409 Owensmouth Ave. CA 91311 (818) 407-0228 (818) 709-2763 (fax) Chatsworth.

Harrison Lab

JBL

Box 1349 Parker. CO 80134 (303) 841-5360 (303) 841-2927 (fax)

80 Crossways Park West Woodbury. NY 11797

P.O.

Hart

(516)

496-3400 496-4868

(fax)

International Jensen

Box 186 Kent. WA 98035 (206) 852-4049 (206) 852-1203 (fax) P.O.

HiFonics Corp. 501 Broad Ave. S.

NJ 07657 (201)945-8880 (201) 945-1218 (fax) Ridgefield.

Hirschmann Industrial

Row

Box 229 Riverdale. NJ 07457 (201) 835-5002 (201) 835-8354 (fax) P.O.

Hollywood Sound

11650 Goldring Rd. Arcadia. CA 91006 (818) 301-7828 (818) 301-7833 (fax) Image Dynamics

4215 Konya Torrance. (310)

(516)

Dr.

CA 90503

370-0159

25

Tri-State Intl. Office Ctr.

400

Suite

Lincolnshire. IL

60069

JL Audio 2321 SW 60th Way Miramar, FL 33023 (305) 981-9497 (305) 987-7855 (fax)

JR Speaker 16216 Gundry Ave. Paramount. CA 90723 (310) 529-8900 (310) 529-8909 (fax)

JVC Company 41

of

America

Slater Dr.

Elmwood Park. NJ 07407 252-5722 (201)523-3601 (fax) (800)

KEF

Electronics of

America

89 Doug Brown Way

MA 01746 429-3600 (508) 429-3699 (fax) Holliston.

(508)

315

ources

Kenwood 2201 E. Dominguez St. Long Beach, CA 90810 (310) 639-9000 (310) 604-4488 (fax Kimber Kable

2752

S.

(801) (801)

1900 W.

UT 84401

Ogden,

621-5530 627-6980

(fax

Mass Engineering

KLW 20121 48th Ave. West P.O. Box 1237 Lynnwood, WA 98036 (206) 775-1202 (206) 778-9453 (fax

505 E. Euclid Compton, CA 90224 (800) 678-1910 (310) 603-2260 (fax)

LA Sound 14508

S. Garfield

Paramount, (310)

Matsushita Electronic Corp. of

Kraco

(310)

1647 Acme St. FL 32805 (800) 545-6277 (407) 872-5772 (fax) Orlando,

CA 90723

602-0152 602-1390

Linear

Ave.

America (Panasonic)

50 Meadowland Parkway (201)

Maxitron

2535 W. Woodland Dr. Anaheim, CA 92801 (714)995-6195 (714)

(fax)

Power

11837 Kemper Rd. CA 95603 (916) 823-7891 (916) 823-5649 (fax)

Auburn,

NJ 07094 348-7000

Seacaucus,

MB

995-0241

(fax)

Quart

25 Walpole Park S. Walpole, MA 02081 (508) 668-8973 (508) 668-8979 (fax) Mcintosh

Lynns Corp.

2 Chambers

1195MahaloPl. Compton, CA 90220 (310) 635-8877 (310) 635-1274 (fax)

Binghampton,

316

St.

NY 13903

723-3512 (607) 724-0549 (607)

(fax)

ources

MEI 1166 W. Chestnut Union. NJ

07083

(908)

964-9001 964-9006

MFR

Engineering

(908)

10308

(317)

(fax)

46236

587-4623 587-9623

(fax)

Michael Sears Electronics

#257 27909

1851 W. Ehringhaus Elizabeth City.

515 Sandydale Rd. Rancho Nipomo. CA 93444 (805) 929-3251 (805) 929-3251 (fax) Monster Cable

Indian Lake Blvd. S.

Indianapolis. IN

(317)

Monolithic St.

NC

St..

(919)331-1193

274

Wattis

Way

San Francisco. CA 94080 (415)871-6000 (415) 871-6555 (fax)

MTX 4545

E. Baseline Rd.

Phoenix.

AZ 85044

438-4545 (602) 438-8692

(fax)

Morel Acoustics

USA

(602)

Milbert

18 Warrior Brook Ctr. Germantown. MD 20874 (301) 540-8827 (301) 428-0831 (fax)

M&M 338 S.

San Francisco.

(415)

588-3075 588-3512

St.

MA 02146 277-6663

Brookline.

(617)

MTX

Electronics

N. Canal St.

(415)

414 Harvard

#16

The Pointe

CA 94080

4545

at

South Mountain

E. Baseline Rd.

AZ 85044 438-4545 (602) 438-8692 (fax) Phoenix.

(fax)

(602)

MMATS 863 W. 13th

Ct.

FL 33404 (407) 848-7578 (407) 848-8152 (fax) Riviera Beach.

Nakamichi America

19701

S.

Vermont Ave.

CA 90502 538-8150 (310) 324-7614 (fax)

Torrance, (310)

Mobile Audio Reference Systems

14417 Chase St. Box E-315 Panorama City. CA 91402 (916) 967-0391 (818) 765-8328 (fax)

Navone Engineering

4119Coronado Stockton. CA 95204 (209) 465-3450

317

Sources

Obcon 1305 S.

Pioneer Electronics

WA 98032 813-1600 (206) 813-1556 (fax)

2265 E. 220th St. Box 1720 Long Beach. CA 90801 (800) 421-1404 (310) 952-2247 (fax)

ORA

Polk Audio

9410 Owensmouth Ave. Chatsworth. CA 91311 (818) 772-2700 (818) 991-3072 (fax)

5601 Metro

Suite

Central Ave.

G

P.O.

Kent, (206)

Orca, Design.

1531 Lookout Agoura,

&

Polydax Speaker Corp.

CA 91301

707-1629 (818) 991-3072

(fax)

Oz Audio 1300 SW 10th St. #2 Delray Beach, FL 33444 (407) 279-0072 279-0051

(fax)

Tri-State

Suite

Int'l.

Jensen) Office Ctr.

Int'l.

400

60069

753-6736 (708) 317-3826 (800)

Philips

S.

Phoenix, (800)

Power 38th

St.

AZ 85040

627-6937 437-4427

(fax)

Profile

17211

S. Valley

(310)

View Ave.

CA 90701

802-9007 404-7317

(fax)

(fax)

N.

MN

524-6638 (612) 559-8412

55442

(800)

318

(fax)

Proton

9600 54th Ave.

3i

Precision

4829

(310)

USA

Minneapolis.

01887

5920 E. Slauson Ave. Commerce. CA 90040 (213) 722-3333 (213) 722-1122 (fax)

Cerritos,

Lincolnshire, IL

MA

658-0700 (508) 658-0703 (508)

(602)

Phase Linear division of

Dr.

Power Acoustik

Tempe, AZ 85283 (602) 730-8200 (602) 831-8101 (fax)

25

10 Upton

Wilmington,

Orion 118 W.Julie Dr.

(a

(800)

Mfg.

Dr.

(818)

(407)

Dr.

MD

21215 377-3600 (410) 358-3600 (fax) (416) 847-8888 (Canada) Baltimore,

(fax)

16826 Edwards Rd. CA 90701 (310) 404-2222 (310) 404-2322 (fax) Cerritos,

Sources

Sanyo Fisher

Pyle

501 Center

Huntington. IN

46750

(219)356-1200 (219) 356-2830 Pyramid 1501-60th Brooklyn.

(fax)

Southern Audio Services

St.

NY 11219

(718)436-1616 (718)436-1401

USA

21350 Lassen St. P.O. Box 2329 Chatsworth. CA 91313 (818) 998-7322 (818) 701-4149 (fax)

St.

15049

Baton Rouge,

(SAS)

LA 70819

843-8823 (504) 272-9844

fax

Inc.

Florida Blvd.

(800)

(fax)

Quinn

6322 Seven Springs Blvd. #A Lake Worth. FL 33463 (407) 585-3534 (407) 433-4295 (fax)

Savard

10132 Mammoth Ave. LA 70814 (504) 928-4270 (504) 928-4362 (fax) Baton Rouge.

Raw Power 5730

Lincoln Ave. Tower Des Moines. IA 50310

274-6063

(515)

Rockford Fosgate P.O. Box 1860 Tempe. AZ 85280 (602) 967-3565 (800)238-7011 (fax)

C

Scosche

5160Gabbert Rd. P.O. Box 8099 Moorpark. CA 93020 (805) 523-0687 (805) 523-0761 (fax) Sentrek

751 Racquet Club

Dr.

60101 628-6767

Addison. IL

Rodek P.O. Box 486 Bellingham.

WA

(206)671-0790 (800)238-7011

(708)

(708)628-0911

(fax)

Sherwood 14839 Alondra

Blvd.

98227 (fax)

La Mirada.

R&T

Enterprises

(800)

1310 S. 13th P.O. Box 883 Kelso.

WA

(714)

98686

(800)451-9779 (206) 423-3396

(fax)

CA 90638

962-3203 521-4900

SJA 9344 Glenoaks

(fax)

Blvd.

Sun Valley, CA 91352 (818)768-8011 (818) 768-8013 (fax)

319

ource

Sony

Stillwater Designs

One Sony

P.O.

Dr.

07656 222-7669

Box 459

OK 74076 624-8510 (405) 377-3272 (fax)

Park Ridge. NJ

Stillwater,

(800)

(405)

Sound Barrier 6971 NW51st. Miami, FL 33166 (305) 594-3928 (305) 594-0969 (fax)

StraightWire

1909 Harrison St. #208 Hollywood, FL 33020 925-2470 925-7253

(305) (305)

(fax)

Sound Quest

2600 Commonwealth Ave. 60064 (708) 473-1200 (708) 473-2436 (fax)

Summit 12420 Montague St. Arleta, CA 91331 (818) 890-3025 (818) 890-5103 (fax)

Soundstream 120 Blue Ravine Rd.

Targa

N. Chicago, IL

Folsom, (916) (916)

CA 95630

351-1288 351-0414

(fax)

Sparkomatic

Toshiba

Box 277 Milfurd, PA 18337 (800) 233-8837 (717) 296-6887 (fax) P.O.

82 Totowa Rd. Wayne, NJ 07470 (201) 628-8000 (201) 628-1875 (fax)

Special Edition

U.S.

NW Platte Rd. Riverside. MO 64150 2970 (816) (816)

587-3433 587-3422

(fax)

Speco 1172 Rt. 109 Lindenhurst, (800) (516)

^\

11400 Downey Ave. Downey, CA 90241 (310) 923-7601 (310) 923-6302 (fax)

320

Inc.

Ultimate

NY 11757

645-5516 957-9142

Amps

7325-100 N.W. 13th Blvd. Gainesville, FL 32606 (904) 338-1926 (904) 371-4122 (fax)

(fax)

138 University Parkway Pomona, CA 91768 (800) 829-9919 (909) 594-0191 (fax)

mm

Sources

Universal Electronics

4917 W. OaktonSt. Skokie. IL 60077 (800) 533-3350 (708) 673-8239 (fax)

USD

ABC 116 Craig Rd. NJ 07726 (800) 354-1324 Englishtown,

Audio

1030 N. Main Orange.

St.

CA 92668

(714)997-9880 (714) 997-7360

(fax)

Box 1437

Cedar Ridge.

CA 95924

(916)477-7323 (916) 272-7972

AC

Components Box 212 LaCrosse, WI 54602 (608) 784-4579 P.O.

Audio Excellence 143 West 26th St.

Vertek P.O.

Mail-order dealers

New York, NY 10001 (212)229-1622

(fax)

A&

S Speakers

Volcano

3170 23rd

470 Stanford Rd. Danville. KY 40422 (606) 236-4050 (606) 236-7476 (fax)

San Francisco.

St.

CA 94110

Audio Video

2898

Wave

(800)

4015Scottsdale Dallas.

(214) (214)

#35 33065

N. University Dr.

Coral Springs. FL

348-7799

Dr.

TX 75227

388-3446 381-6467

Beach Sales VFW Parkway

80

MA 02151 562-9020

Revere, (800)

Wrangler

Box 12109 Prescott. AZ 86304 (602)717-1771 (602) 717-1771 (fax) P.O.

Zapco

413

S. Riverside

CA 95354 577-4268 (209) 577-8548 (fax) Modesto.

(209)

BJ Audio Inc. 991 Beachmeadow Cincinnati.

OH

Ln.

45238

(513)451-0112

Damark 7101 Winnetka Ave. N. P.O. Box 29900 Minneapolis. MN 55429 (800) 827-6767

321

Sources

DB

Madisound Speaker Components 8608 University Green

Systems

Box 460 Rindge, NH 03461 (603) 899-5121 P.O.

WI 53744 831-3433

Madison. (608)

Electro Works Inc.

Meniscus 2575 28th

100 Highway 34 Mattawan, NJ 07747 (800) 662-8559

Wyoming. MI 49509 (616) 534-9121

Gold Sound

New

4285

S.

Illinois

1284

CO 80110

NY 10016 684-6363 (212) 684-8046 fax New

Dundee Rd.

Palatine, IL

60067

Parts Express

621-8042

(800)

340

E. First St.

Dayton,

Whitney 1917-19 Archer Ave. P.O. Box 8410

J.C.

Chicago, IL

York.

(212)

Audio E.

(800)

Q

60680

OH

Audio St.

Cambridge,

Music World

59-50 Queens-Midtown

45402

338-0531

95 Vassar

J&R

Unit 2

York Wholesale 2 Park Ave.

Broadway

Englewood,

St.

(617)

MA

02139

547-2727

Expressway.

Maspeth Queens,

Read Brothers 593-B King

NY 11378

Charleston,

221-8180

(800)

(803)

Audio/Video Iowa Lawrence, KS 66046

SC 29403

723-7276

Kief's

24th

&

(913)842-1811

Reference AudioVideo 18214 Dalton Ave. Gardena. CA 90248

LAT

(301)517-1700 (301) 517-1732

International

317 Provincetown Rd. Cherry Hill, NJ 08034

RTRD

Leary Enterprises

Springfield, IL

130 Quigley

Blvd., Suite

New

DE 19720

322

Castle.

A

fax

3021 Sangamon Ave. 62702 (800) 283-4644

Samman's Electronics 1166 Hamburg Turnpike Wayne. NJ (800) 937-3537

Stereo World

SBH

USA

Enterprises

Box 596 NY 10950 (914) 782-6044 P.O.

Monroe.

Brooklyn.

Media Junction 9 Whippany Rd. Whippany, NJ 07981

(800)

(800)

1678 53rd

St.

NY 11204 451-5851

6th Avenue Electronics

1030 6th Ave.

New

NY 10018 394-6283

York.

(800)

The Sound Approach 6067 Jerico Turnpike Commack. NY 11725 (800) 368-2344 Sound City Meadtown Shopping Center Rt. 23 Kinnelon. NJ 07405

872-1002

Wholesale Connection 63-48 108th St. Forest

Hills,

Amplifier

DC

NY 11375 kits

Electronics

Box 3203

P.O.

AZ 85271 423-0070

Scottsdale,

(800)

The

Electronic

P.O.

Goldmine

Box 5408

AZ 85261 451-7454 (602) 451-9495 (fax) Scottsdale.

(602)

Sound Ideas (516) 864-6548 (516) 864-6437

Mark V

8019 The Sound

Seller

2808 Cahill Rd. P.O. Box 224 Marinette. WI 54143 (800) 826-0520 Speaker World 535 Tabor Rd.

NJ 07950 984-5200 (201) 538-2578 (fax) Morris Plains.

E.

Electronics

Slauson Ave.

Montebello.

CA 90640

(213)888-8988 (213) 888-6868

(fax)

Optoelectronics

5821 N.E. 14th Ave. Ft. Lauderdale, FL 33334 (800) 327-5912 (305) 771-2052 (fax)

(201)

323

!WE_Jt3l8L__

Glossary A

active crossover

amplifier

A mono

crossover unit that requires external power.

or stereo

component

that

is

used to boost the signal

in

strength between the audio source (head unit) and the speakers.

antenna Any

object that is used to pick up radio signals. For best an antenna should generally be cut to a length that is resonant frequency at which it is intended to be used.

A

aperiodic enclosure

damped

results,

at the

closed-box speaker enclosure with an acoustically

pressure vent.

Azimuth Locking Pins (ALPs) Two (DCC) player

that pull the tape in

pins in a Digital

Compact

Cassette

from the back side and lock

it

against

the heads.

closed-box enclosure sides so that the air

from that which

crossover

A

bandpass

is

A

simple speaker enclosure that

mass

behind

in front of the

speaker

is

sealed

on

all

entirely separated

it.

system of highpass and lowpass filters)

is

filters

(and possibly also of

that are used to direct low-frequency audio to the

woofers, mid-frequency audio to the midrange drivers, and high-

frequency audio to the tweeters.

damping (magnetic) The

reduction in the speaker cone's ability to

move

properly.

damping materials Sound-absorbing a speaker

*i

324

box

layers that are

to reduce the reflections

and

added

to the inside of

"tighten" the sound.

xxxxxxxxxxxxxxxxx

V X X X X / s /

Digital

Compact Cassette (DCC) A new

information

is

digitally

same size as a standard compact cassettes.

A

length of pipe or

plastic shell.

cassette.

The

DCC

some other

plastic shell

is

is

which

in

is

held

almost the

players can also play standard

ducting material that

transmit energy or to tune an enclosure. In one of applications, the duct

medium

recording

recorded onto ferromagnetic tape that

onto reels within a small

duct

Glossary

connected to the port

its

is

used to

most conspicuous

ported-box enclosure.

in a

dust caps The dome-shaped caps that are sealed around the center of the speaker cone over the area of the voice coil. The main purpose of dust caps is to protect the electromagnetic inner assembly from being ruined by dust or dirt.

Fixed Azimuth Tape Guidance (FATG) mechanism In a Digital Compact Cassette (DCC) player, the set of edges that guides the tape and makes sure that it moves across the tape heads in exactly the same position each time.

ground The which

is

point in a circuit that is used as a zero-voltage reference and connected to the Earth or to a circuit that is filling in as a

substitute for Earth.

ground loops more highpass

Differences

different

An

filter

in

components

the ground reference voltage between two or in

the

same system.

electronic circuit that holds back

and only allows the frequencies

certain point

all

that are

frequencies below a

above

this

point to

pass through.

impedance The line,

opposition to an alternating current, which

component, or

circuit.

Impedance

is

measured

in

is

inherent in a

ohms.

impedance mismatch The

inability to match the impedance (in ohms) between two stages in a piece of electronic equipment. Impedance mismatches can cause damage to either stage of the equipment.

input sensitivity The sound-pressure delivered to the speaker. This

meter from the front of the speaker,

lowpass

filter

level that

measurement

is

is

at a given

output

when

1

W

taken at a range of

frequency (usually

is 1

1

kHz).

An

certain point

electronic circuit that holds back all frequencies above a and only allows the frequencies that are below this point to

pass through.

325

Glossary

A component

with two separate sources of variable resistance. When one resistance element is connected in parallel to the speaker and the other is connected in series. When the L pad is tuned, it

L pad

it is

installed,

can reduce the output to the driver while maintaining a steady impedance.

midrange speakers Speakers

that are designed to reproduce audio in the

middle frequencies.

nominal power handling The

rating for the

amount

of

power

that a

speaker can handle continously.

passive crossover

A

crossover unit that does not require external power.

peak power handling The

rating for the instantaneous

amount

of

power

that a speaker can safely tolerate.

port

A

hole in a ported-box speaker enclosure that

is

used to tune the

system.

A

ported-box enclosure

type of speaker enclosure that features a port

which a tuned duct can be

in

fitted.

resistance The opposition to an electrical signal flow. The opposition dissipates the extra energy and changes it into heat. resistor

An

electronic

component

that limits the flow of a signal through a

wire.

sampling The process by which a compact

disc player plays a sound, then

checks the source, then plays another sound. This cycling occurs 44,100 times per second (44.1 kHz).

skin effect The

scientific

property by which electricity travels on the

outside (the "skin") of a conductor.

skirt In the graphed frequency response of any type of point from where the

where the

filter

signals are entirely cut off.

steeper that this

filter,

the skirt

is

the

begins to cut off the frequency to the point

The narrower

this distance

is,

the

skirt is said to be.

Compact Cassettes (DCC). a protection device that covers openings to the cassette to prevent dirt from entering the shell and to prevent other objects (such as fingers, pencils, etc.) from entering the bottom of the housing and damaging the tape.

slider In Digital all

sound pressure

level (SPL)

sound stage The that affect the (height),

326

and

The

level of

pressure of sound in the

positioning of the sound as you hear

sound stage are front and back and right (width).

left

it.

(depth),

The

air.

positions

up and down

speaker basket A metal basket

that holds the speaker

components and

provides the necessary strength and rigidity to hold the entire unit together.

speaker cone When the voice coil, which is connected to the speaker cone, pumps in and out within the magnet, the cone in turn pumps in and out from the center of the speaker, somewhat similar to the action that a piston makes.

spider Like the surround, the spider

is

connected to the speaker cone and

the speaker basket. Likewise, the spider also helps to control the

speaker cone and prevent a distorted shape that would consequently distort the

sound

quality.

stiffening capacitor

A

very-high-valued capacitor that

is

used

in

conjunction with dedicated power amplifiers to temporarily store

When

electricity.

a large power-drawing signal peak drains

all

available

power, the stiffening capacitor unloads and helps prevent clipping, especially in the bass frequencies.

subs Slang

for

subwoofers. Sometimes considered to be vulgar by

audiophiles.

subwoofers Speakers especially

that reproduce the very low audio frequencies, below about 500 Hz.

surround A soft, flexible material that is used to control the speaker movement and also to absorb energy from the speaker cone. It must be flexible

enough

to allow the speaker

cone

to freely

be strong enough to keep the speaker cone

suspension The combination

of the surround

both

flexible materials that are

as

pumps

it

in

pump

in

and

out. yet

in place.

and the

spider,

which are

designed to spring with the speaker cone

and out and yet hold

it

in

place without shape distortion.

harmonic distortion (THD) When the amplifier produces harmonics of the input audio source that distort the audio. For an

total

accurate reference.

THD

should be rated across the entire audio

spectrum, from 20

Hz

20 kHz.

transmission line

1.

A

to

cable, usually coaxial cable,

where a radio

signal

flows either from a transmitter to an antenna or from an antenna to a receiver. 2.

A

passage that

air

pressure

is

forced to travel through a

small duct at the bottom of a transmission-line enclosure.

tweeter

A

speaker that

is

designed to reproduce high-frequency audio.

327

Glossary

voice coil A very fine gauge of wire wound around a bobbin, which fits in between the permanent magnet and the iron core in the center. The voice coil moves according to the magnetic fields that are created as the electricity flows into the speaker.

speaker cone to

pump

in

and

The

out,

voice coil

which

is

movement causes

the basis for hearing

recorded or transmitted audio.

woofer A speaker

Q

328

that

is

the

all

designed to reproduce low-frequency audio.

X V V V X

•"••••

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Auto Sound

&

Security. 8/94, p. 78-80. Miller, Terry.

"Get Started." Car Audio and Electronics. 3/94,

p.

100-104.

"Heavy Weight Mercury Cougar," Car Audio and Electronics. 36-44.

Miller. Terry.

2/94,

p.

Miller. Terry.

p.

"Tools the Pros Use." Car

Mitchell. Peter p.

Audio and Electronics. 5/94.

78-86.

W. "Does Size Matter?," Car Audio and Electronics. 6/94.

102-116.

Mitchell, Peter

W. "Nine High-End 10-Inch Subwoofers," Car Audio and 106-122.

Electronics. 3/94, p.

332

Bibliography

Navone. David. "Troubleshooting," Car Audio and Electronics. Monthly column.

Navone. David and Clark. Richard. "Back to Mono." Car Audio and Electronics. 5/94, p. 88-94.

"1994 Car Audio p.

Car Audio and Electronics. 4/94,

Directory."

91-262.

Pettitt. Joe. "Sound Decision: Upgrading a Basic Car Stereo System," AUTOtronics. 8/94, p. 74-81.

Pohlman, Ken C. "MD-Go-Round," Car Stereo Review. 5 93-95.

&

6/94,

p.

Pohlman. Ken C. "Test Reports: Philips DCC-130 Portable p. 46-48.

DCC

Player,"

Stereo Review. 12/93.

"The Premier® Optical Electronics

Digital

Reference System," Brochure. Pioneer

USA.

Shackelford. Dale C. "Salvaging Flooded Electronic Products," Electronic

Servicing

&

Technology. 2/94.

Shepler, John. "Data Signals

Technology. 5/92,

p.

p.

Coming

p.

to Radio," Electronic Servicing

&

54.

Shepler. John. "DAT: Digital Audio

Technology. 1/92,

42-43.

Tape

is

Near," Electronic Servicing

&

40-41.

Shepler, John. "Tricks

Enhance Audio Performance." Electronic Servicing

&

p.

Technology. 9/92,

62.

Smith, Manville. "Dual Voice Coils," Car Audio p.

and

Electronics. 6/94,

94-100.

"Speaker Buyer's Handbook", (brochure) Stillwater Designs 1990.

&

Audio,

Inc.,

Auto Sound & Security. "Equipment Report: Rockford Fosgate Punch 200ix." Auto Sound & Security. 8/94. p. 40-42. Staff of

Truesdale. Richard. "MiniDisc Mania," AUTOtronics. 5/94, p. 58-61.

"What

is

DCC?"

Brochure. Philips Car Stereo.

White, Glenn D. Small Technical paper Ziffer.

Amy

V.

Room

number 107.

"What's

New

In

Acoustics DeMythologized. AudioControl, (c)

1991.

CD

Changer Features," Car Audio and

Electronics. 6/94, p. 86-92.

333

t^

Index alternative frequencies (AF).

39

classes of audio,

78-80 principles of. 77-87

86 86

Class-A. 82-83.

Class-C.

83 84

Class-D.

84-85

clipping.

99

current-starved problems.

98-99

308-309 dedicated external, 33-34 design configurations. 94-100 distortion. 93 dedicated,

and equalizers. 34. 106 101-115

equalization

feedback,

kits,

107

ratings.

216 215-218 shortwave radio. 253 phased-array, practical.

space-diversity reception.

104-105

vehicle.

218

213

whip. 209. 211. 214-215

108-110

321

load impedance and

334

104 88-89 supplies. 96-100 repairing. 308-309 size, 76, 105 speaker-level input. 106-107 specifications. 89-92 stereo separation. 100 thermal protection. 107 using stiffening capacitors. 112-115 antenna systems. 209-218 AM reception. 213-218 basics regarding. 209-211 locations and, 211-212 motor noise. 212 power power

shortwave reception. 213-218

87

gold-plated connectors, installing.

102

plug-in modules.

111-112 amplifiers. 20-21, 33-34, 75-116 advantages/disadvantages. 33-34 bridgeability, 107 Class- AB. 84,

106

of available channels.

overload protection, 107

amplifier-level tweaking.

gain control,

92-93

number

82-86

history,

features,

or stereo. 94-96

noise.

noise reduction.

amplification

Class-B.

mono

audio systems. 1-35 stability.

91-92

equipment selection

listing.

26-35

evaluating your needs. 18-26

changers

manufacturers. 311-321

cleaning discs,

purchasing (see purchasing)

cleaning laser optics assembly, 306-

285-309 wiring, 232-236 audio technology. 37-43 repairing.

audition function,

43

51

51

disc capacity,

changer

features,

automatic radio

FM

46

49-51

units,

307

307

automatic bias selector. autoreverse,

head

disc access time,

disc

47 muting. 40

vs.

unit,

26, 41

51-52

transmitters

for,

intro scan function,

226-228 52

226

average input power, 90

portable,

average output power. 90

problems with skipping, 305-306 random access, 51

azimuth locking pin (ALP). 59-60

remote control. 52

B

repairing.

237-238 blank skip, 46

repeat function,

batteries.

building,

305-307 52

307 86 Class-AB amplifiers, 84, 86 Class-B amplifiers, 83 Class-C amplifiers, 84 technical adjustments,

speaker enclosures, 177-185

bulletin-board system (BBS). 13. 140.

310

Class-A amplifiers, 82-83,

Class-D amplifiers, 84-85 cables (see wire and cabling systems) capacitors, stiffening, Carr, Joseph.

112-115

clock time (CT),

common mode

86

cassette decks,

44-47

99 39

clipping amplifier,

compact

rejection

disc player (see

(CMR), 106

CD

advantages/disadvantages, 27-28

competition, sound-offs, xiv

automatic bias selector, 47

control circuits,

autoreverse, basics.

features.

active vs. passive, building,

46

head cleaning. 301 head demagnetizers. 302

299-303

188-189

buying,

188-189

components, 192 cutoff slope,

193

determining parts and values to use,

music sensor. 46 noise suppression,

187-208 189-191

Butterworth, 194-195

45-47

muffled audio,

40

crossovers, 22, 73, 101.

46

44-45

blank skip,

player)

46

power load/power eject, 47 repairing, 299-304 tapes getting eaten, 302-303 tuner call, 46 wrong or variable tape speed, 303-304 cassettes, digital compact, 53, 58-64 CD players. 47-52 advantages/disadvantages, 28 basics. 47-49

200-203 determining speaker crossover points,

197-200 193-194 195-197 L pads, 206-208

first-order,

fourth-order,

mixing/matching different orders

of,

205 orders of, 193-197 resistance,

207-208

335

MMFMMPM' M Index

fixed azimuth tape guidance (FATG). 59-

crossovers continued

194-195 theory. 189-197 third-order. 195-197

60

second-order,

frequency

187-188 197-203 rate. 187

uses

maximum usable. 256 minimum usable. 256

for.

speaker

values. cutoff

39

alternative.

three-way speaker systems. 203-205

130-137

classifications.

236-238. 308

fuses.

G

D

107 297 grounding. 238-240 ground loops. 239 gain control.

damping, 122, 162-164 DAT decks. 52-53

Homer

Davidson,

DCC decks.

305

53, 58-64

63-64

availability,

cassette

L..

DCC differences.

and

mail-order information,

MiniDisc and

DCC DCC

Group head

grill

DCC

58-61

of America.

H head

64

similarities.

19-20. 37-71 (see also

units.

cassette decks:

62

DAT

players:

64

CD

players: MiniDisc

decks:

DCC decks)

advantages/disadvantages. 34-35

units.

equipment selection features. 38-43 high-power. 34-35 installing, 64-71

advantages/disadvantages, 29-30 DeForest. Lee. 78

diaphragm. 118 digital

audio tape (see

digital

compact

digital signal digital

cloth.

DAT decks)

cassette (see

DCC

pullout,

decks)

processing (DSP). 71-72

security

42 299-307 methods, 24

shortwave equipment. 252-253

93

with shortwave radio reception. hearing, damage/loss of.

290-292

electron tubes. 78.

80-81

electrostatic discharge.

106

equalizers. 22-23.

advantages.

34

298-299

F 42 87

22. 186.

Linkwitz-Riley,

336

143-144

amplifiers.

108-110

audio systems

faders, 22.

filters,

91-92

input sensitivity. installation

preamp, 73

feedback.

I

impedance, 146 load.

72-74

74

amplifiers and.

repairing.

292-293

30

xi-xii

76

heatsinks. electrocution, 212.

equalization.

27-30

repairing,

sound processor (DSP), 23

distortion.

listing.

1975 Ford Granada. 268-270 1981 VW Rabbit. 259-266 1986 Chevrolet Celebrity, 273-280 1990 Geo Tracker. 278-284 building speaker enclosures.

195 195

ground,

head

239

units.

64-71. 273-277

177-185

Inde

speakers. 258-260.

o

techniques.

Ohm's

278-280 256-284 wiring audio systems, 232-236 integrated circuit (IC). 79 Internet. 140

law.

91

online services,

140

(see also bulletin

board system: Internet) overload protection. 107

ionosphere frequency changes. layers,

L

255

246-248 peak input power. 90 peak output power, 90 peak power handling, 145 polarity, speaker. 145-146 power. 20-21 amplifier ratings. 88-89 head units and. 40-41 nominal handling for speakers. 145 peak power handling for speakers, 145 watts per channel, 20-21 power load/power eject, 47 power supplies. 96-100 preset memories. 41 program identification (PI), 39

206-208 41 function. 40

pads.

LCD load

display.

load impedance.

91-92

local/DX control. 42-43

M magazines. 3-6. 310-311

magnets. 121-123 mail-order companies, 8-10 dealer

listing,

321-323

traffic.

manufacturers, 311-321

maximum

usable frequency.

256

metal-oxide semiconductor field-effect transistor

(MOSFET). 81

purchasing

midbass, 133

midrange. 132 MiniDisc players. 53-58

advantages/disadvantages, 29, 55-57

CD and disc size.

minimum

mono mono

MiniDisc differences.

55

53-54

beware of stolen equipment, 12, 16 from bulletin-board systems, 13 from classified advertisements, 10-13 from discount department stores, 6-7 from installation shops, 2-3. 13-15 from mail-order companies, 8-10, 13-

usable frequency,

256

94-96 subwoofers. 95-96

amplifiers.

music sensor. 46 mute. 41

15 from pawn shops. 15-16 from second-hand stores, 15-16 from shows and flea markets, 16-18 magazine sources, 3-6 new equipment, 2-10 speakers,

N noise.

39

program service name (PS), 38 program type (PT). 38 propagation. 246-249

92-93

motor,

137-143

used equipment, 10-18 wire/cables.

212

220-221

267 106

reducing. 106.

suppressing,

troubleshooting charts.

242-243

nominal power handling. 145

radio display system (RDS), alternative frequencies,

38-40

39

337

Index

radio display system (RDS) continued

clock time.

39

crossovers: equalizers; faders;

program identification. 39 program service name. 38 program type, 38 traffic announcement identification.

39 identification,

radio technology.

39

37-43

210 receivers.

37

reception (see antenna systems) recording, amplifier-level tweaking and.

111-112 remote control, 42 player,

52

206-208. 223

resistance,

response, speaker.

144

289-293 212

safety,

antenna,

CD

players and.

sampling.

305

48

scanning, 41-42 security.

codes.

23-26

24

semiconductors. 79

shortwave radio. 244-257

antenna systems. 213-218. 253 auto audio equipment. 252-253 broadcasting,

head

249-251

units with reception for.

30

information regarding. 254-257 local

and international broadcast bands.

245 music heard on, 250

246-249 Ill skin effect, 223 soldering. 230-231 sound. 117-121 pressure level, 88 stage, 120-121 waves. 119 propagation.

signal-to-noise ratio.

338

sources.

310-323

speaker cones. 125-128

damaged. 293-294

128

for. 125-127 294-297 sound and, 118 speaker enclosures. 155-185 aperiodic. 168-169 bandpass. 170-171 building, 177-185 closed-box. 164-167 damping. 162-164 designs and techniques. 164-177 materials used for, 156-159 ported-box, 169-175 shapes. 159-162 transmission-line, 175-176 speakers. 117-154 advantages/disadvantages. 31 basket. 129 choosing. 141-143 classifications by frequency. 130-137 components. 121-130 connections. 129-130 impedance. 146 input sensitivity. 143-144 installing. 278-280 interconnecting. 146-152 dual voice coil. 151-152 in parallel, 147-148 in series. 148-149 in series and parallel. 150-151 level inputs. 106-107 magnets. 121-123 midbass. 133 midrange. 132 multiple-driver. 31. 135-137 nominal power handling. 145 peak power handling. 145 polarity. 145-146 purchasing. 137-143 raw. 31

materials used repairing,

radio theory, basic principles regarding.

filters).

22

dust caps.

program

traffic

CD

sound-processing equipment (see

repairing.

response. security

293-298 144 26 143-146

measures

specifications. spider.

V voice

for.

coils.

dual,

129

121. 123-124

123-124, 151-152

surrounds. 128-129.

w

suspensions.

watts per channel (see power)

297-298 128-129 tweeter. 131. 187 voice coils. 121

Weems, David

woofers and subwoofers. 31-33. 133-

coaxial cable.

FM

134

247-248 static electricity. 292-293 stereo separation. 100 stiffening capacitors. 112-115

transmitters for

CD

players,

making connections, 228-231 planning and assembling audio system,

16

subwoofers (see woofers and subwoofers)

256

sunspot cycle.

219-243

225

226-228 grounds, 238-240

sporadic-E skip.

stolen equipment. 12.

158, 177

B.,

wire and cabling systems.

232-236 power cables and

fuses.

236-238

purchasing considerations. 220-

221 222-226 225 230-231

shapes/styles.

thermal protection, 107 total

harmonic

traffic

shielded cable.

distortion (THD).

announcement

93

identification (TA).

39

types,

39

program identification 117 transistors. 79

(TP).

transmission-line enclosures.

175-176

traffic

call.

286-289 noise. 242-243

46 187

230

230

134 advantages/disadvantages, 32-33

33 32

enclosed. free-air.

tweaking, amplifier-level. 111-112 tweeter. 131.

using terminal blocks,

woofers and subwoofers, 31-33, 133-

troubleshooting. eliminating

242-243

221-222

using wire nuts.

transducers,

tuner

soldering.

troubleshooting charts.

mono. 95-96 standard-mount.

32

339

MB

•yxxxxxy

About the author bed with the covers pulled up high. Andrew Yoder began listening to music on the radio late at night when no one else in the house could hear. Since that time he has taken his music everywhere and found ways to make In

is an extension of this desire. In addition to Yoder spends numerous hours glued to the radios, in search of shortwave and pirate broadcast stations.

the system work; auto audio listening to music.

in Radio!. Popular Communications. Popular Jersey Monthly, and he writes regular columns for

His articles have appeared Electronics, and

New

America and Europe. His recent books include Underground Broadcasts. Build Your Shortwave Antennas, and The Complete Shortwave Listener's

several newsletters in North

Pirate Radio Stations: Tuning into

Own

Handbook

—4th Edition.

341

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