IT'S GETTING CLOSER TO HOME
by Ivan Berger
SOUND EQUIPMENT for automobiles has changed over the past few years, and very much for the bet ter. Once it consisted of no more than an AM radio installed at the factory, the only options being pushbutton tuning and an extra speaker in the back.
Today, when only about 15 percent of car audio systems are factory-installed, you can have your choice of AM, FM, stereo FM, stereo cassette or eight-
track tape, and even quadraphonic eight-track. You can also get up to 125 watts of power per channel and two way, three-way, and even bi-amplified speaker systems (that is, separate amplifiers for each driver in the speaker system).
Options that lead to higher-price systems aren't the only reason Americans are expected to spend over a billion dollars this year on sound systems for their cars. Long drives often provide a better opportunity for uninterrupted listening than the same time spent amid the chores, distractions, and responsibilities of home. Traffic congestion and lower speed limits make those drives longer too, and they add to the desirability of having a pleasant sonic stimulus available.
A Car Is Not a Home
Listening in the car is not the same as listening in your living room: it's both better and worse. The list of problems car stereo must overcome is long: high ambient noise (as much as 40 dB or so above home noise levels); equipment failure due to heat, cold, dampness, or vibration; and sound distribution com promised both by the difficulties of mounting speakers where they sound best and the impossibility of rearranging the seats to suit the speakers.
What's good about car listening is that, if you get it right, the sound can combine most of the virtues of both speaker and headphone listening and that the bass you hear is better than even the most optimistic speaker specs would lead you to believe.
Experts differ on just why this should be so. Speaker authority Abraham Cohen of Polydax summed up the most popular view in a recent Audio Engineering Society paper: listeners in the small space of a car's interior are not so much in a listening room as within the speaker cabinet. But Tim Holl, Acoustic Research's director of engineering, disagrees: "It's not that the car forms an acoustic-suspension enclosure; you can open doors and windows and still get more bass from a speaker than one would think from anechoic measurements. We suspect it's that you're held in the near field of the speaker." Acoustic Research is just one company noted for home speakers that's also looking into speakers for the car; JBL and Advent are reputedly interest ed also, and car speakers are already available from Altec (distributed by car-sound specialist Clarion), ADS, AFS, Braun, Cerwin-Vega, Craig, Jensen, Panasonic, Pioneer, Polk, RSL, Tru-Sonic, and Utah. Car speakers are beginning to adopt a lot of home-speaker techniques, too.
Trends in Speakers
The biggest trend is to two-way systems, with separate woofers and tweeters. These are available in coaxial form (with the tweeter mounted within the woofer cone's concavity for easier installation) from Audiovox, Boman/ Astrosonix, Cerwin-Vega, Clarion,Jensen, Lear Jet, Magnadyne, Medal lion, Panasonic, Pioneer, RSL, Sparkomatic, and Utah and in non-coaxial versions by ADS, Audio-Mobile, Polk, and Pyramid (the Pyramid is a 6 x 9-inch oval plate containing a round woofer and tweeter). Jensen's Triaxial, the first three-way loudspeaker for the car, has been joined by three-way coaxes from Audiovox and Kraco. Ceramic tweeters are being widely used in two- and three-way car systems, both to save space and because of their resistance to the moisture, jolts, and temperature variations they suffer in the car environment.
Speaker magnets are getting heavier too. While some inexpensive speakers have magnets weighing 3 ounces or less, others are available with magnet weights of 20 ounces or more, comparable to those in home speakers of equal size. Larger magnets are generally used in the interest of increasing efficiency-a definite advantage when you're trying to overcome road noise with only the typical car stereo's out put of about 3 watts per channel to power the speaker. But they also make the speaker bigger and heavier, harder to install, and more likely to vibrate off its mountings. And AR's Holl points out another problem: "The bigger the magnet, the more the speaker is damped at its resonant point. That means less output at and below resonance and less bass. But that's not necessarily a bad thing. In fact, it may sound subjectively better. We suspect that's because more damping also means tighter control of woofer motion when bass notes end." In other words, better transient response.
There's also a big emphasis on speakers with greater power-handling ability. That's not surprising, 'since in some installations today's car speakers have a lot of power to handle. Car stereo units boasting up to 15 watts per channel are already on the market, and booster amplifiers of anywhere from 8 to 125 continuous watts per channel have been announced. Some manufacturers sell their speakers and amplifiers as matched sets. I've not been overly impressed by the 6 x 9-inch speakers that carry booster amplifiers piggyback, but the deluxe systems by ADS and AudioMobile offer car sound for the "carriage trade," and they are priced accordingly.
The first of the auto-audio super systems was the ADS 2001, a $475 ensemble incorporating two two-way speaker systems in metal enclosures each about the size of two bricks and a bi-amplified electronics package delivering up to 60 watts to each woofer and up to 20 to each tweeter-a potential of 160 watts total. The amplifier has some unusual properties: to overcome road noise it provides a mild level boost at low to medium volumes; then, to protect ears and speakers, it cuts back slightly at the highest sound levels-in other words, level compression. The amplifier's bass is pre-equalized to compensate for bass rolloff in the 4-inch woofer, and since this bass boost plus the amplifier's high power could blow unprotected woofers, a circuit limits high bass amplitudes.
ADS's newer 2002 system is similar, but with smaller amplifiers (25 watts per woofer, 5 watts per tweeter) built into the speaker cabinets, and a correspondingly lower price ($395). Unlike the 2001, which is designed for use with any tape deck or sound system, the 2002 is designed primarily to work with the new Nakamichi 250 cassette player or 350 player/recorder.
AudioMobile's approach is consider ably different. Its amplifier delivers a straight 20 to 35 watts per channel, de pending on the speaker impedance it sees, and the crossovers are passive ones following the amp. And Audio-Mobile's speakers don't come with en closures: instead, each channel has a 4-inch dome tweeter and your choice of a 6 1/2- or 10-inch woofer designed to be flush-mounted in the car's interior panels. The company recommends that you install the tweeters near the front of the car and the woofers in the parcel shelf above the trunk.
Speaker Installation
The type of speaker for you is a function of the sound you want and what you are willing to pay for it. The size of speaker is a function of the spot where you'll install it. Several places are in common use: the rear deck above the trunk, the doors, the "kick panels" un der the dash, and the dashboard itself.
Rear parcel shelves in U.S. cars usually have cutouts and pre-drilled bolt holes for 6 x 9-inch oval speakers; most other spots require smaller, round models.
The ideal speaker spot is one where the speaker won't be in the way, where it will have a good-sized cavity behind it to serve as an enclosure, and where it can direct its sounds at the car's occupants from sufficient distance to ensure good distribution. In most cars, though, there is no such spot.
Surface-mount speakers, with their own enclosures, eliminate the problem of finding a suitable cavity that's in a good location, but the cavities built into them are small, which (except on the ADS models, with their equalized amplifiers) limits bass response. Many such enclosures are labeled "acoustic suspension," but it is not unusual to find vents or other openings in them. In any case, sealed enclosure or not, since many of these speakers give perfectly good sound, you should just ignore the claimed operating principle and pay attention only to what you hear. Be alert to one inevitable disadvantage of surface-mount speakers, however: they stick out. That means a door- or dash-mounted surface mount is likely to intercept your knees or elbows, while a badly located rear-deck speaker may obscure your view of cars behind you.
Many surface-mount speakers have open backs, so you can enlarge their volume by cutting a hole in the panel they attach to and using one of the car's cavities as an enclosure. But as long as you're going to do that, perhaps you might as well flush-mount the speakers. And many surface-mounts let you do just that.
FLUSH-MOUNTING on the rear deck is easy in most U.S. cars. You just lie in the trunk and use the cutouts in the metal surface as templates with which to cut the fiber trim panel--if it's not al ready perforated to act as a grille. The trunk provides a big, beautiful cavity for the speaker.
The upward-facing rear-deck speaker's treble is nicely dispersed by the bounce it takes off the car's slanted rear window. But often a rear speaker's sound can't be heard clearly in the front seat even when it's turned up loud enough to blast rear-seat passengers halfway to deafness. Further more, sunlight beats down on the cone, drying and bleaching it. There are rumors (groundless, I suspect) that speaker cones can be damaged by the sudden rise in air pressure when the CAR STEREO trunk lid is slammed. And AR's Holl reports that in all cars tested, shelf-mounted speakers had a dip of about 6 dB in the 600- to 700-Hz range, perhaps because of boundary effects from the nearby slanted window.
Mounting a speaker facing upward in the dash does give good mid-range and treble coverage to the front-seat occupants. But the dashboard, unless its bottom is sealed (few are), is a poor baffle for bass wavelengths, and so the sound may be a bit thin. Sunlight is still a problem. And any speaker-mounting cutouts in the car dash are likely to be in the center-a good place for a mono speaker, but awkward for stereo-and may be of an odd size and shape (say, 2 x 9 inches) that restricts your choice of speakers.
Door mounts are favored by most commercial installers. Doors provide a nice rear cavity, so good bass is assured. They're easy to work on, and sometimes you can even fit the speaker in somewhere up fairly high and well forward-the best possible place. More often, though, removing the door's fabric covering reveals a solid steel panel or a moving piece of window-winder linkage right where acoustics say the speaker should go. Then the speaker may have to be installed at the rear of the door (good sound for the rear seat, but not for any but the most long legged drivers, who push the seat all the way back), or down near the floor, where its higher-frequency output is in danger of being absorbed by the car's carpet or blocked by the legs of the driver and passengers.
Kick panels provide easier installation-you don't have to take the door apart, and often you don't have to cut into metal. But the cavities behind them are usually too small for good bass (in some cars, there's no cavity at all, just the wheel well), and the potential problems of installation near the floor remain.
The grille you choose for your speaker (assuming that it doesn't come with one) should depend on where the speaker will be. Low-mounted grilles should be of shiny chrome that with stands scuffing. Rear-deck or dash board-top mounts require matte-black grilles to avoid reflections that confuse the driver's rear or forward vision or glare that may distract him at a crucial moment. If you can, make sure such grilles aren't made of plastic that deteriorates with heat or sunlight.
The Program Source
Speakers, of course, are only half the story. The other half is what you feed them. Amplifier power, in my experience, can be quite low by home-component standards and still be adequate for a car. Even though car speakers have more noise to outshout, the normal 3 or 4 watts per channel can do a fine job, letting you hear clearly in all but the noisiest situations. More power is always nice, of course, if you're willing to pay for it. Unless you're buying a unit such as the Nakamichi machines, the Uher 210, or the new AM/FM/cassette deck coming from AudioMobile, your tape player will have at least a few watts of amplifier power available. See if that's enough before you invest in a booster amplifier; you can always add the booster later if you need it. But try to get a demonstration of a more powerful system too, for comparison.
The trend in tape players is increasingly toward AM/FM/cassette combi nations that fit into your dashboard's existing radio cutout. Installed there, they're less visible to a potential thief (especially the models whose tape slots are covered by swing-away tuning dials) and somewhat harder to remove.
They're also easier to feed tapes to-if your car's designer gave some thought to where he put the radio-installation slot, that is.
Concerning the trend toward cassette units, the arguments in favor of it are nearly overwhelming-but not quite. The main advantage of cassette over eight-track cartridge is its versatility. If you have (or plan to get) a cassette deck at home, you can swap tapes between your home and car at will.
And though you could record your own programs on an eight-track cartridge deck, it's far easier with cassettes where you don't have to worry about taping into segments that will fit be tween track-change breaks. With cassettes, you can also tape classes and business notes on a pocket-size recorder, then review them as you drive with your car's tape deck. There are some units that let you pick up a microphone and tape your thoughts as you drive, including models from Sanyo, Blaupunkt, and Becker that let you tape stereo FM programs from their built-in tuners. Also, you can buy a bracket that holds Uher's CR-124, 134, and 210 portable stereo recorders. It connects them to your car's battery and-via a control unit on the bracket-to a matching power amplifier that is included in the package.
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THE COMPONENT APPROACH--IS IT BEST?
CAR stereo components, like those for the home, come in separate units or in integrated combinations. Which is the better bet?
Some of the arguments are the same as those for components versus com pact combinations in a home system: combinations cost less, take up less space (especially important in a car), and simplify operation by eliminating redundant controls. Separates let you update part of the system whenever new technology or wear and tear dictate without forcing you to throw out the whole system and start over (and technology seems to be moving faster in car than in home stereo). And separates also let you send one unit in for repair while you keep on listening to the others.
But there are a few arguments that pertain mostly to the car. Combinations can be installed in your dash board where they're less likely to be stolen (though a determined thief can inflict some expensive damage if he tries to get them anyway). Separates let you move an under-dash tape player from your old car to your new without having either to lower your old one's resale value by stripping its radio or lose the value of your tape player by trading it in with the car. Under-dash tape or radio units can often be re moved readily for use or safekeeping elsewhere. And the service problem alluded to above can be quite serious in an integrated unit that combines AM, FM, tape, and perhaps CB in a unit the size of an overstuffed sandwich which then alternately bakes, freezes, and gets shaken like a cocktail.
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For a cassette unit that matches eight-track's convenience of music that goes on until all tracks are played with out requiring any action from you, you have to pay $40 or $50 extra for automatic reverse. On the other hand, cassetter give you real fast-forward (eight-track "fast forward" is only about double normal speed) and rewind. Thus you have instant access to any desired spot on the tape: pop listeners can go straight to the song they want (though it would help if all car-cassette units had digital counters), and classical listeners can easily re-start a symphony from the beginning instead of from the point where the tape last stopped.
Classical tape material seems to be in better supply on cassette than on eight-track (although in pop it's still the other way around). And since the cassette market seems to be strongly hi-fi oriented, sonic improvements are likely to show up in cassette tapes and equipment first. Cassettes are smaller, too, for easier storage, and they are less likely than cartridges to jam. But, on the other hand, at least some cassette-deck mechanisms seem to be less reliable than eight-track units.
One final thought: discrete four-channel tapes continue to remain avail able in the eight-track format, and machines to play them on are sold under a number of brand names. Nonetheless, eight-track-once dominant-is expected to cede half the market to cassette this year.
Radio Tape lets you listen to the music of your choice when you want it, it comes without commercials, and it doesn't fade as you get further from the station. But it can't do everything.
Radio can bring you current news, traffic reports, ads for local shopping when you're in an unfamiliar area, and music that you didn't bring along and therefore haven't tired of yet. And there's little question that you should get both AM and FM. With its longer wavelengths and its many clear-channel stations, AM can carry much greater distances than FM. And there's more news, sports, and talk on AM.
But for high-fidelity music, FM is un surpassed, with far less static and distortion and with a wider frequency range than AM. Also, FM has stereo and fades less when you go under bridges or through underpasses. Be sides, there's a lot of music and even a bit of talk you'll hear only on that band.
For either band, easy tuning is doubly necessary in a car radio. Since you're moving out of range of some stations, you'll need to tune more of ten, and since you're usually driving at the same time, you have less attention to spare. So the first requirement of a good car radio is a dial that is reason ably readable at a glance. (Heath's FM-only tuner kit has one of the better CAR STEREO ones.) The second is some sort of tuning aid to make that dial unnecessary most of the time. The commonest such aid is a row of pushbuttons that can be preset to bring in your favorite stations. In the more expensive radios, you'll usually find five buttons that can be tuned so that each will summon up one AM and one FM station, or ten stations total. Next most useful are but tons that can be set to any combination of five AM or FM stations. Then come the sets which dedicate some buttons just to AM stations, others just to FM.
Pushbuttons are most useful when your trips all lie within the same area, even if it is a large one (I knew a sales man once whose FM buttons followed the Concert Network throughout his New England route). For travel into unfamiliar areas, though, signal-seeking automatic tuning is an even greater help. All you do is push a button and a signal-seeking radio will look for the next strong station on the dial, then lock it in until you either tell it to hold that station or to move along and try the next. Signal-seekers are available from Delco (factory-installed on GM cars only), and from Becker, Blaupunkt, and J.I.L. But with the exception of the $1,200 Blaupunkt " Berlin," which has six station presets on its goose-neck-mounted remote-control module, car radios have either signal-seeking or pushbuttons-not both.
If your car has stereo, get stereo FM.
But look for a set with a manual stereo/ mono switch. Any radio will automatically switch to stereo when the signal is strong and clear, or mono when it isn't (for reduced noise and distortion). But when you're skirting the fringes of a station's stereo signal area, hearing the radio switch back and forth between clean mono and degraded stereo can be very annoying; a mono switch will pre vent that.
Tone controls in most car-stereo units usually consist only of a treble cut control: turning the control to the left may seem to give you more bass, but what it really does is give you less treble. Turning it all the way to the right restores nominally flat response.
Separate bass and treble controls are better, even if they only turn down their respective ranges; controls with both cut and boost are better still. More elaborate controls, including separate bass, treble, and mid-range controls, are available in some car amplifiers, and Clarion has a 15-watt-per-channel amp with a built-in five-band equalizer.
WHAT with equalizers, multi-way speaker systems, bi-amplification, high-power amplifiers, electronic tape-speed controls, and vastly improved FM tuners, the list of home-stereo techniques used in the car gets longer every day. But perhaps the most significant incursion of component ideas has been in the realm of specifications. Slowly, first with car amplifiers, and now with Pioneer's Supertuner FM series (which lives up to its name), units are appearing whose specifications can be compared with those of home units. And as that happens, more and more such units will bear up well under the comparison. All in all, it sounds good for the road.
Ivan Berger, who has written widely on audio subject matter, was recently named senior editor of STEREO REVIEW'S more technical sister publication, Popular Electronics.
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A SAMPLER OF EXTREME TEMPTATIONS
Motorola's TC876AX AM/FM plus cassette unit designed for in-dash installation.
Superscope's CA-20 has AM, FM, and a cassette player with both fast forward and rewind.
Preamplifier of the Uher CR 200 (power amplifier not shown) and CR 134 recorder.
The Pioneer TP-900 "Supertuner" contains an eight-track or cassette tape player.
The unique " cobra-head" control module for Blaupunkt's " Berlin" model multi-band radio.
The ADS/Nakamichi 2002 system provides exceptional cassette playback performance.
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THEFT: HOW SAFE IS YOUR STEREO?
WHILE I was writing this piece, my CB and an Audiovox converter that added TV sound to my car radio were stolen from my car. My tape deck and my radio weren't. I accept the blame for the loss, but I also take full credit for what was saved.
In the first place, my car was on the street, not locked in the garage, and I'd forgotten to lock the door on the passenger side, so getting at the stuff was easy. I'd left my CB antenna up, a fairly sure tip-off that there was a CB radio inside to be stolen, and though I had re moved the CB from its slide-in mount, I hadn't locked it in the trunk, just hid den it from view beneath the seat. The TV sound converter, normally bolted beneath the radio where it looked like a permanent fixture, had broken free of the plastic under-dash panel it was fastened to and was lying loose on the floor, so it looked like easy pickings.
How did I manage to keep my radio and tape deck? The first was firmly mounted in the dash-too much trouble to steal. And the second was in the trunk, where no one would even know I had it.
There are some obvious conclusions to be drawn: whatever isn't mounted in the dash should be removed from the passenger compartment entirely and stowed where a thief isn't likely to find it (in the trunk or inside the house).
Signs that you possess electronic goodies should be concealed as much as possible: CB antennas, microphones, and tapes should be stored in the trunk.
You should also keep, your car locked, and in the safest place you can find.
Don't trust in lock mounts to keep your stereo safe if it is in plain sight.
Some mounts are easy to break into; most are easy to break loose, and a thief who does that is likely to damage your car as well.
What about insurance? Most companies who used to cover sets under the "comprehensive" sections of their automobile policies have recently excluded them and now offer separate cover age for about 10 percent of the unit's worth each year. These policies apply only to units "permanently installed" in cars, which, according to agents I've talked to, means either in-clash units or those bolted under the dash. Units on slide-in mounts are not covered, even if you've hidden them in the trunk or taken them into the house (where they're not covered by homeowners' or tenants' policies either).
So insurability is another plus for in-dash units--if you want to pay the extra cost of the insurance. But I think If d prefer a removable stereo, which I can probably prevent from getting stolen, to an under-dash one whose theft is more likely, though it is more insurable. Whether you will make this choice depends on how likely you are to remember to hide the set each time you park the car and whether you prefer the sure but minor nuisance of re moving the set to the possible major nuisance of having it stolen and waiting for your insurance company's check.
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Also see:
EQUIPMENT TEST REPORTS: Hirsch-Houck Laboratory test results on the: Audio Pulse Model One time-delay system, Avid 101 speaker system, Realistic SA-2000 integrated stereo amplifier, and Shure M24H stereo/quadraphonic phono cartridge, JULIAN D. HIRSCH
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