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By E.T. Canby
For twenty years and more we have been trumpeting about hi fi equipment in all its ever-improving diversity, and yet we've had scarcely a thing for sale that might directly help the acoustic matching element which is most important of all for hi-fi ( except, of course, your ears)-the listening room. Now, to my pleasure, the hi fi makers have discovered the front parlor, and are doing something about it. Many things, all of them, needless to say, costing money; but the intent is to give you satisfaction in return. I think we are on a right track.
We've made a certain amount of fuss over the placement of stereo speakers and, before them, the lone mono speaker that previously had the job of providing an orchestral spread of sound from a single point in the room. We've talked living room decor, and cabinetry and convenience and connections. But the implication has been, right along, that if you buy good equipment, you buy good sound--and don't worry about the room; it'll have to take care of itself.
Nosy I've never subscribed to this particular subscription, not even in my hi-fi youth when I was collecting 78-rpm 12-inchers to play through a huge Midwest 16-tube radio via one of the earliest phono attachments. Even then, I learned to aim my big fat console for maximum distribution and reflection-I hated to have a speaker playing straight at my knees. And when separate speakers came along, I began all sorts of experiments with room sound, having decided by that time that if one could tell where the sound was coming from there was something definitely wrong. I was literal about "filling my living room with glorious sound," if not about that putative best seat in the concert hall.
My preference was to aim an unobtrusive speaker diagonally towards a corner, from one side, with enough hard reflecting surfaces in the way-the curve of a grand piano, backs of wooden chairs--to blur and spread the apparent sound source so that the music seemed to come from a wide area quite removed from the speaker itself. This stunning illusion of space was my special pride and I would have it again, if there weren't stereo to change things. It gave as much realism to mono sound ( which has no literal width whatsoever) as could ever be achieved in that medium. And it took maximum advantage of the living room itself.
Stereo, I might add in parenthesis, creates its own spread of space by the interaction of its two spaced-out signals, as they reach the ear from different directions. The more reflection, the less stereo you get-but our recordings are designed for an average amount of general room diffuseness in reproduction.
A good stereo system, like my mono arrangement, completely disguises the speakers' locations for the ear. The sound is heard from virtual-image sources all the way across from speaker to speaker and (so theory says) well beyond on either side, and all this without the aid of reflection, which now merely smooths down and blunts the sharp directionality.
So, ideally, our rooms are much more adaptable to stereo, just so they don't overdo the reflection business. Too much reflection and you revert to mono. No directionality left.
For this reason I view with some jaundice one of the popular answers now being provided for stereo room trouble-reflecting speakers, aiming up or back or all over, to diffuse the sound source.
My best judgment is that this a fine panacea, substituting a very attractive near-mono effect for a poor stereo one.
A net gain, in many a bad room situation! But not the ideal solution, to my way of thinking. If you're going to hear stereo you've got to have point sources, reasonably direct and unimpeded. Two of them. Real or imaginary.
Real speakers, of course. But also, to an extent, the strange “virtual images" created by Jensen's new one-box speaker system, discussed in detail in Audio for November, 1969 (p. 62), which I have been trying too. Especially in a confined space, the Jensen "Stereo 1" ( one of the year's clumsiest titles) is an interesting answer to room problems.
Definitely, from its single cabinet with the matrixed speakers comes a stereo spread and a stereo sound-but, oddly, I could not really tell left from right.
It did not seem to matter, for the important thing in stereo is, speaking subjectively, the heightened immediacy of apparent hall sound, at least for classical music, my main fare. The Jensen system projects it remarkably, and should do well in boats, camper busses, hotel rooms, where the virtual images will seem to emanate straight from the other side of the nearby walls.
One element in the listening room, though, has until now been carefully left alone, for lack of much that the manufacturers could do about it, that frequency balance of the total room, with associated resonances, standing waves and what-not, which converts the flattest of loudspeaker emissions into a jagged and peak-filled "curve" in every living room. We live all the time with these gross distortions of the original, and the living isn't half bad. But it would be good if we had at least the power to do something about it. Only the pallid tone controls, raising or dipping a wide butterfly wing of highs and lows, have been provided in the attempt to match our systems to our rooms. Suddenly, a whole array of gadgets is now available designed precisely to cope in detail with this very problem. I note three, including the one I have been trying myself, the Advent Frequency Balance Control, designed to plug into your system before the amplifier and warp its sound selectively to mirror the room characteristics in reverse.
Now it happens that in 1964 CBS Labs put out its "Seven Steps" test record ( for which I wrote the rambling commentary), a gallant attempt to provide specific tests for room sound as your ears actually hear it via ingenious subjective comparisons, octave by octave in frequency over the entire sonic range and point by point (to pick up stray buzzing resonances) via glide tone. This pink-noise test, along with some simpler equipment adjustments, indicated the desirable corrections remarkably well--but there was nothing we could do to put them into effect. The over-all tone controls were virtually useless.
And so I have just mated together the 1964 test disc and Advent's astonishingly similar octave-by-octave contouring gadget, a beautiful little machine with two rows of ten vertical sliders each ( for stereo), moving above and below a "flat" center-line position, each slider controlling a sharply defined octave of boost or cut, from 40 Hz to 20 kHz. It works! Even though the successive CBS test tones, comparing a pink-noise burst with a loudness reference frequency (also pink noise) are more closely spaced than Advent's sliders, two or three to each octave. So much the better. It was astonishing how accurately the Advent picked up the CBS third-of-an-octave bands of pitched noise (covering approximately a musical third in pitch width) and boosted or attenuated them, via the slider, to match the standard reference tone in loudness. On a single playing of the record I was able to come out with a visible room "curve" which, just incidentally, rather neatly matched a known deficiency in my speaker system, a dip in mid-range. I can see that on more careful repeated trials I could narrow down some of the room resonances which show up vividly on the glide tone (which sounds like a piston plane going through a thunderstorm) and adjust narrow single segments of the frequency range to reduce their impact on my ears. Never before has this been possible outside of a fairly fancy audio lab. Who listens to music there? The Advent Balance Control is an intriguing toy, too, and you will have as much trouble as I did getting down to systematic work with it. Fascinating to hear the selective vowel-like whines, as one or another segment of, the spectrum is suddenly boosted 'way up. Interesting to discover how much harder it is to hear "holes" of the very same magnitude. Is that significant for listening! The peaks are what show. Wonderful to find that a sharp boost as high as 160-320 Hz still gives the impression of a bass boost, however addled; whereas 320-640 (next slider) is for the ear clearly treble.
That tells something about small speakers and hyped-up low ends. Nice to realize that the middle ranges, from 500 up to 5000, are so thoroughly in control of apparent volume level. Boost any segment in that range and the overall volume pops up. Not so nice to find that the extreme right slider, 10,240 to 20,480, has no audible effect at all on my ears. That's for kids.
I hate to think how we're going to raise the cash to pay for such beautifully built gadgetry as this. But I also hate to think of giving up my newfound corrections. Granted that our biggest listening advantage is that we get used to our own sound situation and quickly learn to treat it as normal or "flat," just as we adjust to colored light after a while and see it as white. Even so, in the quest for perfection it is always better to start right and adapt later. So I am all in favor of this development, for those who can afford it. Perhaps a slightly-very slightly-simplified version may some day appear in our best amplifier-control systems for the home?
(Audio magazine, Apr. 1970)
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