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dbx Soundfield 1A speakers

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology
 

Simple gray rule


dbx Soundfield 1A speakers: 8 woofers, electronic EQ and the best way of clearing out the house
 

By Al Fasoldt

Copyright © 1986, The Syracuse Newspapers

It is not hard to make a loudspeaker that sounds good. Ever since the first acoustic-suspension speakers were developed three decades ago, loudspeakers have been sounding better and better. But that does not mean they have been sounding accurate. The fact that those two concepts are not necessarily related was brought to mind during a long-term evaluation of a new and expensive speaker system from dbx.

The system is the Soundfield 1A, which consists of two large loudspeakers and a small electronic device called a controller. The list price is $2,950. In a day when discount hi-fi stores are selling loudspeakers for $110 a pair, what makes the Soundfield speakers worth nearly $3,000? The answer, based on months of listening, amounts to only one thing: in all conceivable situations, they sound real. That, of course, is the same as saying that the big dbx speakers are accurate.

They achieve their startling you-are-there quality by a combination of two techniques. One is a brute-force approach to basic sound reproduction. Knowing that the very lowest frequencies are the ones that are hardest to generate, dbx's engineers placed four large air-suspension woofers in each enclosure. With eight of these woofers working together, bass notes are no challenge at all. Even the chest-thumping sonics of pipe organs pose no problem. They rumble up from the floor around the dbx speakers, just as if you were sitting in a cathedral.

The electronic controller makes the bass even more impressive by shaping the left and right stereo signals for optimum low-bass accuracy. As an added touch, the controller eliminates all signals that are too low in pitch to hear, so that turntable rumble and other sonic garbage can't ruin the sound. Multiple tweeters help also, as do a pair of powerful midrange drivers.

The tweeters ring the upper surface, beneath a protective wooden cap. The other technique is a brilliant application of an old way of making the sound seem to fill the room. As Bose has shown with its successful Model 901 speakers, by bouncing most of the sound off the side and rear walls, speakers can produce a stereo effect that seems larger than the actual room.

For orchestral recordings, this can put Symphony Hall right in your living room. But this enlarged effect doesn't work well with smaller groups, and sometimes speakers that bounce the sound around can make a jazz combo seem like it was playing inside Carlsbad Caverns.

What was needed, according to dbx, was a way of controlling the amount of sound that reflects off the walls and other surfaces of the room. What the company did was to take the listener into account, to make sure that no mater where you were seated, you would get the proper combination of direct and reflected sound. The engineers did this by aiming each speaker's primary sound output not at the listener but at the other speaker.

In other words, the Soundfield loudspeakers talk mostly to each other. This strange state of affairs is not as weird as it seems when you consider what happens to the stereo sound all around the speakers. If you sit directly in front of the speakers, halfway between them and 10 or 12 feet away, you will hear equal percentages of the left and right channels, and the stereo image will be balanced. If you move far to the left, you will be closer to the left speaker than the right one, and so you will hear the left one clearly.

But you will also be right in the firing line of the right speaker, which is aimed toward the left. As a result, you will get clear sounds from that side, too. The stereo image will remain balanced, with equal sounds from left and right. The same thing happens if you move over to the right.

In fact, as my investigations showed, no matter where you sit or stand, you cannot shake the stereo image loose. Even if you position yourself directly over one of the speakers, the spread of stereo sounds is still clearly laid out from left to right.

The effect is no less than stunning. The regular speakers that I use for my own listening are very good, and the sounds they produce are pure and airy, but in terms of accuracy they are no matches for the speakers from dbx. In fact, in the illusory art of producing a stereo perspective that sounds realistic anywhere in the room, the Soundfield speakers probably can't be beat.

In another way, the dbx speakers are probably untouchable, too. They will play louder at all frequencies than just about any pair of high-fidelity speakers available to the public. Some designs may play louder at the easy-to-play midrange frequencies, but it seems clear that the Soundfield speakers are the ones to consider if you like organ music, the sound of giant Indonesian gongs, or the roar of orchestral drums running full tilt.

And the dbx speakers are perfect for clearing guests out of your house, too, as I found out while running routine checks of low-frequency performance. I was playing, as loudly as possible, the first band from a test and demonstration compact disc called "The Digital Domain," which begins with birds chirping and ends with the landing of a jetliner.

My houseguests found the tweet-tweets entrancing, and they marveled at the soothing bubbling of a mountain brook that followed. But when the Boeing touched down, the ceilings quaked and the floors palpitated _ and my guests ran outside to see whether a 747 was about to hit the house. If that's not realism, I'll eat my CD.


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