GRILLE CRAZY

Optical Inputs

People with hearing problems often put their glasses on to answer phone calls-and not just when those glasses have hearing aids built in. The phenomenon is well known, but its cause is still a mystery. A while back, the British magazine Electronics and Wireless World suggested that clearer vision might lighten the load on those areas which process both hearing and sight. The item also suggested that "if our glasses make us see better, then subconsciously we expect all our senses to improve." Our sight affects our hearing in other ways. For example, we're likely to perceive more and lower bass from big speakers than from small ones which measure the same. Philips used to demonstrate a small, feedback-controlled speaker by hiding it within a huge speaker enclosure until listeners got used to its bass.

More recently, researchers at Wharfedale proved that perceptions of a speaker could be altered by changing the color of its grille cloth! More than 300 college students were asked to compare ostensibly different speakers, which could be identified by their grille colors. Actually, the speakers were identical except for the color of the cloth. To the students, speakers with red grilles seemed more bassy, speakers with yellow grilles seemed louder, and blue grilles made the sound seem clearer.

Speakers with black or brown grilles--the colors most commonly used-were considered lifeless or dull. When the grilles were secretly interchanged, the listeners continued to feel that red meant more bass, and so on, even if during the swap, the red grille was put on the "clearer sounding" speaker that previously had sported a blue grille.

Cost vs. Culture

The LP record offered music lovers better sound and greater convenience than the 78-rpm disc which preceded it, just as CD offers the same advantages over LP. But the LP also cost less than the format it replaced. As a result, the 33 1/3-rpm disc (and the new convenience of record mastering on tape) spawned a musical revolution, allowing listeners to hear composers and performers they had never heard before. I doubt that Pachelbel, Neville Marriner, or Philip Glass would be well-known names today without the low-risk appeal of LP's economy. I suspect the same would be true of many pop, jazz, and rock artists.

So far, the CD is spawning no such revolution. Quite the reverse, in fact. It is, as Francis Davis recently wrote in The Atlantic Monthly, "a format still so expensive that consumers feel safer sticking with the tried and true." It's easier to take a flier on the unknown when the price of the flight is $6 rather than $16.

However, the price of CDs is creeping downward, for three reasons: Initial investments in CD plants have been partially amortized.

Improved production technology is cutting costs. And a temporary excess of production capacity is forcing manufacturers to cut prices, both to attract business away from their competitors and to increase overall CD sales.

At the same time, DAT offers a relatively inexpensive, portable mastering medium that should encourage recording companies to try new musicians in new venues, just as tape did in the '50s. So far, DAT does not match open-reel tape's ease of editing, but because digital tapes can be copied with no loss of quality, there should be no problem dubbing DAT masters to other digital formats for which studio editing facilities are available.

Because DAT is a two-channel medium, it may lead to better sound by forbidding the sloppy techniques and overmiking which 24-, 32-, and 48-track tapes allow. Just as they did in stereo's early days, engineers will have to get their mike placement and mixing right, and musicians will have to perfect their performances, rather than "fixing it in the mix." This, too, harks back to the early days of stereo tape mastering (except that many early stereo masters were on three track tape). Add DAT convenience to CDs priced below the $10 consumer acceptance barrier, and you could easily have another flowering of musical adventurousness.

Nonetheless, there are voices in the record industry crying against any reduction in CD prices, arguing that lower prices will cut CD profits without expanding the market. Only people who get their recordings free from friends in the business could believe that lower prices would not increase sales. And while lower prices would cut industry profits in the short term, market expansion would eventually make up for that.

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Down the Drain

For the average driver, the power drawn by a car stereo system is most significant when the system and the car are in operation. We've all heard tales (and maybe seen examples) of systems which drew so much current that the headlights dimmed on every beat. For city-dwellers like me, however, what matters most is the drain on the electrical system when everything's shut off.

For moving around within the city, it's usually easier (and faster) to take a cab than to take my car; as a result, I sometimes do not drive my car for three or four weeks at a time.

When my car was full of stereo equipment, it usually wouldn't start after two weeks in the garage, would rarely start after three weeks, and never started after a month of inaction. The drain from an inactive stereo is minor-a few pilot lights, some preset station memories, the amplifiers' turn-on sensing circuits, and perhaps a digital clock-but it does add up, over time. Assuming a 50 amp-hour battery must lose three quarters of its power before it can no longer start the car, then a constant drain of only 100 milliamps or so will render the car un-startable after two weeks. That's why I've mentioned battery problems several times in this column. When the system was in, my jumper cable was my most valuable audio accessory.

But then I removed the stereo system, in preparation for my shift to a new car. I didn't drive the old buggy again for six weeks after that; when I did, it started right up.

In my new car, I think I'll add a cutoff switch to limit the battery drain when the car is not used for several weeks. Anyone know where I can get a big, fat, 12-V relay that can stand the underhood environment?

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Phasing the Music

Books on stereo, and most amplifier or speaker instruction books, stress the importance of ensuring that the left and right speakers are in phase with one another. Otherwise, if the left speaker pushes when the right one pulls, low bass frequencies are cancelled, and imaging becomes uncertain.

In car stereo, we must also make sure that the rear speakers are in phase with the front ones. A red-faced industry executive just told me he'd belatedly discovered that this had not been done for his car. When he corrected the anomaly (a simple matter of reversing the leads of both rear speakers), bass response picked up considerably.

The simplest way to check the phasing of your car's system is to slowly move your system's front-rear fader control from one extreme position to the other while playing music with plenty of low bass. If you hear less bass when the fader's at its middle setting than when it's set to full front or full rear, then you probably have this problem, too.

If this is inconclusive, reverse the wiring on your rear speakers and run the test again. Whichever wiring setup gives you more bass when the fader's centered is the correct one.

How much more bass will correct phasing yield? We recently compared frequency response curves from two cars of the same model, one with improperly phased rear speakers, the other with correctly phased speakers. The results are not 100% accurate because the tests were performed in different labs, but even allowing for that, the difference is striking. With all speakers playing, the misphased system had a substantial roll-off below 160 Hz, and its output was down (re: 1 kHz) about 15 dB at 40 Hz; the correctly phased system's output was actually up 2 dB at 40 Hz!

(adapted from Audio magazine, nov. 1988; by IVAN BERGER)

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