YOU PROBABLY think the only way to get better stereo sound is to buy a stereo that sounds better. A couple of years ago you would have been right. But a series of ingenious new inventions -“black boxes” in audiophile parlance -has changed all that. They plug right into your hi-fi and heighten fidelity in a way that a better stereo can’t: by giving music the stunning realism of a live performance.
These black boxes are also surprisingly affordable, costing as little as $100. As one Dallas audio consultant put it, “For the owner of a reasonably good stereo who is dissatisfied with its sound, the black box approach will yield by far the best dollar-for-dollar improvement.” And what your dollars will buy is music with the impact and immediacy of the concert hall -any time you want it -right in your own living room.
The reason stereo systems don’t sound like real performances has relatively little to do with the fact that recorded sound is electronically processed; the problem is with your listening room. The concert hall is a large, open, acoustically designed space; your living room isn’t. The symphony orchestra -even the rock or jazz band -occupies a sizable stage from which sounds emerge at precise locations. The stage in your living room is only as wide as the distance between your speakers (say eight to 10 feet), and the sounds only come from its outer edges. More than anything else, these spatial properties make the concert hall sound brilliant and immediate, with visceral impact and an enveloping warmth. They also make the stereo in your living room sound like a stereo in your living room.
So what about these new inventions? They will amaze you, that’s what. There are several types, each one designed to eradicate a specific sonic difference between the concert hall and your home; and they do it surprisingly well.
Before getting down to details, here’s the bottom line: Suppose you have just purchased a box setup and are sitting down to enjoy some Wagner. After you place the record on the turntable, you move to your “listening chair.” (Black boxes can be very finicky about where you sit, where you put your speakers, how things are situated; indeed, you have rearranged your living room for the best effect.) You are listening to a full romantic orchestra -30 violins, 16 woodwinds, thunderous percussion -and it sounds like nothing less. You are in a warm bath of music, with the tonal fullness of a large hall, rather than the thin line of sound your system used to produce. Even though it’s the same recording, the soft passages are softer and the loud ones louder than before. And when the music gets quiet, the hiss, pops, and ticks you used to hear don’t mar your enjoyment; other than the instruments, there is only silence.
Most of all, you are struck by an effect so astounding that you can hardly believe what you are hearing. To your ears, the orchestra is arrayed on a stage as large as the one at the music hall. Close your eyes and, sure enough, the sounds are clearly emanating from an area that goes beyond the walls of your listening room. And everything is where it should be. The violins extend to your left, the double basses bellow on your right, the timpani thunders from deep at the back of the stage. And you are (where else?) front row center. Open your eyes and you’re in for a shock. The sonic illusion doesn’t disappear, only now it’s obviously an illusion. You can clearly hear the first violins projecting through the door from your dining room; the cellos are perched on the bookshelf at the opposite wall; and the remote corners of the stage aren’t even in the house-all of the percussion is in the front yard, and the double basses are in the driveway. Or so it sounds. All the while, incredibly, there stand your two speakers, a few feet apart in front of you-the left one among the second violins, the right one between the violas and the cellos.
Technically, black boxes are electronic circuits that change the stereo signal before it reaches your ears. Some look like hand calculators, others like receivers or cassette decks or other familiar audio gear. They have awesome-sounding names: sonic holography generators, image restoration systems, dynamic range expanders, autocorrelators, peak unlimiters, digital time delay systems, ambience, restoration devices, dynamic noise filters, parametric equalizers, and transient noise eliminators. Your hi-fi dealer will probably refer to them collectively as signal processors.
But forget the jargon; there are really just five types. Image enhancers (the ones that put the bassoonist on your neighbor’s patio) are the most interesting technically; they literally expand the stereo stage over a much larger area as well as sharpen and localize the position of individual voices and instruments. Time delay systems recreate the patterns of sound waves in real performing environments, an essential part of the concert experience. Equalizers ensure that a stereo system gives the same emphasis to all audible frequencies. Dynamic range expanders restore the extremes in volume that the recording process removes. And noise reduction devices suppress the various types of unwanted noise that sneak into recorded music. In summation, black boxes attack whatever separates your stereo from the real thing. Let’s take a peek at each type of black box, the problem it confronts, and the way it does its magic. The way they work is every bit as amazing as what they do.
Image Enhancers. Remember the advent of stereo in the Fifties when every new console system came complete with a demo record? The announcer started with a few sonic parlor tricks like walking between the speakers and bouncing a ping pong ball; then he glibly worked up to the skidding car that scared the family half to death. It was all pretty flaky, but he had a point: Stereo reproduction creates a spatial image.
It begins with the recording process. In a concert hall, music is recorded on two or more microphones at different locations. By directing sounds recorded on the left side of the hall through your left speaker and sounds recorded on the right side through your right speaker, your stereo recreates the positions of the instruments on the stage. In the recording studio, where instruments may be taped separately, the performers are artificially positioned on the stereo stage during the mixing process.
But your stereo’s reproduction of space is beset with “cross talk,” the blurring and condensing of the image because the sound of each instrument is reproduced by both speakers rather than at a single point in space. The result is a vague localization of instruments on a small stage between the speakers.
A few years ago, an audio engineer from Woodinville, Washington, named Bob Carver set out to change all that. He began by studying the workings of the human brain. Scientists have long known that we perceive the direction of a sound by the difference between what the two ears hear. A sound emanating from one side is heard first by the near ear, then by the far one because it takes time (a fraction of a second) for the sound to travel the distance around the head. The farther the sound is to the side, the greater the delay. The brain notes this and automatically computes the direction of the sound.
Carver’s idea, borrowed in part from studies that date back 20 years, was nonetheless brilliant. If you could present each instrument to the listener’s ears with the same time-delay characteristics heard at a live performance, the brain’s little reflex calculations would precisely reconstruct the original positions of the performers; put them all together and the entire orchestra would burst into realistic dimension. But that would require two things: sufficient information in the stereo signal and the ability to distill it from obscuring cross talk. As it turned out, common stereo record grooves were up to the task, as was Carver. Hence, the double basses in the driveway.
But be warned, image enhancement devices are no picnic to set up. They hook easily enough into your system with a few patch cords, but the problem is speaker placement. Under any circumstances, putting speakers too close to reflective surfaces,- especially side walls, creates reflected waves that keep the image from developing. This is also true with image enhancers; you have to experiment with different placements that open up the image without ruining the decor. These devices are not for active listeners. They are most effective in a small area roughly equidistant from the two speakers, so you need to sit down and stay there. Carver’s first model of a year ago had a particularly narrow range, requiring a “listening chair,” but more recent versions have enlarged the prime location somewhat.
Once you hook it up, arrange your speakers, and plop down in the right place, there is nothing vague about what you hear. With everything correctly adjusted, not only does the stage expand dramatically (both in width and depth), but there is also an uncanny sense of pre-ciseness about exactly where each performer is located. With the lights out, our au-ditioners all had the same eerie sense that the room was occupied by sonic ghosts. The sounds really do emerge from exact points in space corresponding to the positions of the performers during the recording. With a small ensemble, each instrument and voice is clearly etched in space (separated by several feet rather than tumbling out on top of each other) so the listeners can turn their attention from one to another, hearing nuances previously unnoticed.
If you enjoy listening to music at home, an image enhancer can make even very familiar material fresh and exciting. You might even find yourself going back through your record collection from start to finish.
There are several image enhancers on the market; we have heard four of them. The Carver unit, now a second generation model, yields the greatest expansion and is free of audible side effects. Available at Melody Shop, it comes in three formats.
The C-4000 is a veritable pantry full of black box circuits, including a full-function preamplifier with some of the most flexible tone controls ever designed, a dynamic range expander, a noise reducer, and a time-delay system. For somebody ready to take the plunge, they are all here in one package. Given what you get, the $960 price tag makes it a steal. The $550 C-l is a preamplifier with the image enhancer built in, and the $279 C-9 is an image enhancer by itself, ready for installation in any stereo system.
The IR2100 Image Restoration Control by Sound Concepts is almost as dazzling as the Carver and has several unique advantages. First, it is small enough to fit in your hand, and since it is connected to your system by a 12-foot cord, you can make all adjustments (as well as a direct comparison between processed and unprocessed sound) right in your listening chair. Second, it’s more adjustable than the Carver. To a great extent, you can tune the unit to your speaker location rather than the converse, which removes much of the hassle. Third, this system is at its best with the speakers near rear walls (not side walls), which is usually more convenient than Carver’s away-from-all-walls recommendation. The Sound Concepts unit is also available at Melody Shop for $250.
A system called the Omnisonix 801 Imager is available for both home and car stereos. We haven’t heard the mobile version, but the home unit struck us as less effective than the Carver or the Sound Concepts models. However, it did afford noticeable expansion, was inexpensive ($199), and seemed not to care a whit where the speakers were placed. It can be purchased at Hillcrest High Fidelity, Arnold & Morgan Music Company, Recorder Center, and Melody Shop.
A very interesting development is Yamaha’s move to include a spatial expander circuit in its entire line of superb receivers (radio tuners together with complete amplification and system control). They offer a significant imaging improvement for anyone interested in a quality receiver. Yamaha products are sold at Hillcrest High Fidelity and Arnold & Morgan Music Company.
Time Delay Systems. The biggest single disparity between the concert hall and your home listening environment is the size of the room, which makes an enormous difference. The problem is that sound bounces. What you hear in a performing environment is a mixture of two types of sound waves: those coming to you directly from the instruments (which reach you first), and those that have been reflected off the walls, floor, ceiling, and other reflective surfaces (which are delayed due to their circuitous routes). Indeed, in many halls, 80 per cent of what you hear is reflected sound; the tonal richness and resonant timbres of the concert hall derive from it. For the most part, it is this proper proportion of reflected sound striking the ear from all directions that we miss at home. Sound bounces in your living room, but the small dimensions impart an unnatural effect, and the music is thin by comparison.
Audio engineers have devised a solution as ingenious as it is complex: the time delay system. Although there is a vast difference both in approach and sophistication, the various models all work their magic by creating replicas of music hall reflections and injecting them into your listening room. First, the audio signal is split in two; one path goes to your speakers as usual, the other is sent through the time delay circuitry where it is processed to sound like the reflected waves in a concert hall. Then it is played through two or more small additional speakers so that it mixes in your room with the main signal. Voilà! Instant realism. Not that it really knocks you over the second you press the button; but listen for a few minutes and then turn it off. The music collapses from all around you back into the main speakers, and the musical richness and warmth you were enjoying are gone. With the unit back in operation, listen carefully; the music really does sound like it’s being made in a large hall.
Like all black boxes, time delay units must be set up properly to be effective. The added time delay speakers should be located at the sides of the listening position and placed so as not to fire directly at it. Also, the numerous possible settings should be made with care. Particularly, too strong a delayed signal or one with too much reverberation will sound artificial. But hook it up right, and it will do more than anything else to make your music sound real.
If you’re interested in a time delay system, you’ve got more than two dozen choices. They range in price from $400 to $5000. Additionally, many of them require the separate purchase of speakers (about $300 per pair) and even an amplifier (another $200). We’ve heard a number of them and can recommend three. Two excellent units are the ADS 10 Digital Time Delay System ($1150 with amplifier, but without speakers) and Benchmark Ambience Retrieval Unit ($829 without speakers or amplifier). Both are very flexible (turn your room into a nightclub, symphony hall, or cathedral – you pick the exact size and sonic characteristics -at the touch of a button) and will produce incredibly realistic results. The ADS can be purchased at Recorder Center and Arnold & Morgan Music Company, and the Benchmark at Hillcrest High Fidelity. We consider another model, the Koss K/4DS Digital Delay System, to be an exceptional value. Not as sonically stunning or as flexible as the best units, it is nonetheless easy to use and offers a good measure of realism and depth of sound. The best part is that it costs $430 complete with amplifier and speakers. Melody Shop carries it.
Equalizers. No listening environment should emphasize or de-emphasize any part of the audible spectrum. If that occurs, tonal balance disappears and, depending upon the nature of the imbalance, music can sound bad in any of a hundred different ways. It is a hard and fast rule that good sound requires even treatment of all frequencies.
Unless you designed your room around your stereo, you’re in for some tonal aberrations, maybe some serious ones. If that is the case, your stereo won’t sound good no matter how much it costs. The answer is an equalizer. An elaborate tone control, it allows you to make detailed adjustments to the response of your system throughout the audible range.
The most common setup is called an “octave equalizer” because it contains a control for each of the 10 audible octaves. Most offer a separate set of controls for each speaker (20 in all). Better still is the “third-octave equalizer,” which gives three controls for each octave. Each control cuts or boosts (at your option) the volume of sound in its range, usually as much as 12 or 15 decibels. You boost the tones in which your system is deficient and cut those that are overabundant until your tonal response is even. This kind of “equalizing” provides substantial benefits to most home setups and very often makes the difference between unsatisfying sound and great sound. It also has been a real money saver for many home listeners who had thought they needed a new system. The equalizer is truly a black box for the masses because of its relatively low cost (from $120) and universal benefit.
So how do you know by listening which controls to adjust and how to adjust them? You don’t. Equalizing by ear is like target shooting in the dark. And unless the Force is with you, you’ll most likely make matters worse. Proper equalization is done by reference to an instrument known as a spectrum analyzer. By using a microphone, test tone, and visual display, the analyzer tells you how much and where you need to cut and boost and when you’ve got it right. Buy a spectrum analyzer or hire an audio specialist who has one. Your best bet is to purchase one of the several new equalizers that has a spectrum analyzer built into it; you can get a very good one for $550.
There are probably 50 equalizers on the market. The Audio Control C-101 Equalizer is a high-quality octave equalizer with an excellent spectrum analyzer built in. It comes equipped with a calibrated microphone and test tone generator that allow hassle-free equalization 10 minutes after you’ve read the owner’s manual. It also includes two types of noise eliminators and an attractive display screen that analyzes the tonal response of any music played on your system. At $550, it is cheaper than most analyzers alone. For the budget-conscious, the Audio Control 520B offers a five-band-per-channel equalizer that will work well in most applications and costs only $120. Audio Control products are sold at Hillcrest High Fidelity and Melody Shop. For the price-is-no-object set, dbx makes a $1500 equalizer/analyzer/computer that automatically equalizes your system at the touch of a button for each of 10 different locations in your listening room, stores each in a memory, and recalls any of them, or their average, at your command. You can see one do its stuff at Hillcrest High Fidelity, Arnold & Morgan Music Company, Recorder Center, and Sound Climaax.
Dynamic Range Expanders. Variations in volume level have a great deal to do with musical impact. Unfortunately, the composer’s meticulously noted pianos and fortes often don’t make it to your stereo system because of limitations in tapes, records, and FM broadcasts. For a variety of reasons, those media suffer from muted loud passages and boosted soft ones to produce a kind of mid-level mush. The records are getting better, at least on the classical front, but there seems to be no immediate hope for radio and prerecorded tapes.
Dynamic range expanders make low-level sounds play lower and loud ones play louder. The result is a much broader volume spectrum and increased impact that is more like live music. After you’ve listened to a good one for a while, it’s hard to live without it. The increased dynamics they give to music can be particularly appreciated by apartment dwellers and other low-volume listeners.
If musical impact is important to you, a good range expander will make you happier with your stereo sound. RG Dynamics makes two excellent expanders ($255 and $420), and dbx makes three good ones ($260 to $700). We like the RG approach better because it processes each channel separately, which aids the stereo image. See RG products at Hillcrest High Fidelity and dbx equipment at Recorder Center, Sound Climax, Arnold & Morgan Music Company, and Hillcrest High Fidelity.
Noise Reducers. Everybody is familiar with hi-fi noise. Turntables rumble. Tape decks hiss. Records snap, crackle, and pop. Any of these intrusions can turn your listening enjoyment into irritation. Better equipment and newer recordings will cure the problem. But let’s face it; even though your records and tapes may not be in great shape, you’re not about to spend several hundred dollars replacing the whole batch. Besides, maybe you like your 1962 version of Fidelio.
Hi-fi noise reducers operate with varying degrees of success. Three years ago, none of them seemed to work well. Now there are several that do their job very effectively. We tried two hiss reducers that were extremely competent in reducing the noise level without causing ill effects on the music until we increased their action to the maximum; the hiss virtually disappeared, but so did the highest musical tones. Still, on some very hissy sources, we preferred the maximum setting. Also, the pop and tick reducers miss some of the smallest crinkles and leave muted thumps in the place of very loud pops. But most of the noises disappear without a trace, and the thumps are far less obtrusive than what they replace. Clearly, the owner of a vintage record or tape collection can upgrade the purity of his sound with the better noise reduction equipment.
We consider the best hiss suppressor to be Carver’s “autocorrelator.” It has a manual setting knob and a computer-controlled automatic level control. The automatic setting really quiets the hiss and doesn’t seem to affect the high frequency music at all. The only problem is that it is available only as part of Carver’s decked-out preamplifier, the $960 C-4000; Melody Shop carries it. Phase Linear’s $400 model 1000 Series Two offers an excellent hiss and rumble reducer together with a dynamic range expander; Pacific Stereo stores stock it. Advanced Audio-System’s DNR-450 is a good new $200 hiss reducer; as yet, however, we haven’t found a Dallas store that carries it. For pops and ticks, SAE’s 5000A does a good job (but make sure you’re getting the 1981 improved version), as does KLH’s TNE 7000. Hear the SAE at Pacific Stereo and the KLH at Melody Shop.
That’s the state of the black box art today. What new magic can we expect in the near future? How about a computer with an image enhancer, time delay system, equalizer, and analyzer built in? After it automatically reads the sonic characteristics of your listening room, you decide where you want to hear your next selection. Oh, say Carnegie Hall. You punch in a code. Done. It copies -down to the last decibel and cubic foot – the best acoustics on the globe. Why not? It’s only a matter of consolidating present technology into one instrument.
The ultimate question is whether black boxes offer good sonic return for your stereo dollars. Most experts agree that if you love music, the answer is yes.
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