WAS PHASE THE ANSWER?
Two continuing items this time around: The Stereophoner of Dr. Hermann Scherchen, and more fun & games with Technics' Studio Collection.
Things are seldom what they seem, observed Gilbert & Sullivan a century ago, adding that, all too often, skimmed milk masquerades as cream.
Can mono masquerade as stereo? In the 1950s could an enhanced mono, two channels derived from one, be taken as a serious popular challenge to the then complexities of true stereo, with two of everything? Indeed it could and Dr. Scherchen's Stereophoner was not the only try, then or since, towards a mono-derived dimensional soundspace in audio reproduction for a big improvement over the point-source beaming of sound from a single loudspeaker, most people's only audio experience before stereo.
As per my May account, an impressive variety of European listeners "raved" over the novel effect of Scherchen's realistic spread of sound. His device was perhaps unique in having behind it such an energetic and famous, even awesome, promoter during its brief success.
I left the Stereophoner in May at the point of its somewhat sensational meltdown in my kitchen, filling the place with noxious fumes, running red rivers of hideous potting gunk to reveal at last the inner components of this peculiarly elementary gadget. Inside the small metal cube there could only be a handful of parts of the sort that were standard in the 1950s. Maybe even none at all? Just an illusion, a sleight of ear? Possible but not probable. Dr. S. could hardly have gotten away with that, if indeed he wanted to.
Inside the de-potted box I found only three components and a bit of wire. One leg of the mono input (15 ohms) did in fact run straight through, a solid ground to the metal case and maybe the nearest water pipe. No floating grounds in those days. (If I am right, most early stereo used the same sort of common ground for both channels.) The other input leg, "plus," went to the business elements, a pot or rheostat marked 50 ohms, a small unmarked electrolytic "condenser" (capacitor), aluminum clad, and a choke coil with a laminated iron core, this last covered with dense varnish as well as potting gunk. That was it.
My cooperative technician friend in San Francisco, working at Pacific Stereo, took one look at the mangled mess I sent out to him and pronounced himself "aghast." But he wasn't about to leave it at that. He immediately reassembled the Stereophoner (minus gunk) and, without measuring anything, set it to work. Good man! Listen first. That's the attitude I like. "Gadzooks!" he exclaimed, and made this further comment: "It does indeed provide a convincing bass-right, treble left early fake-stereo image. Could be quite nice to listen to." This from a man who has heard a million stereo systems of much more recent date. Might the sound have seemed even better for listeners in the late 1950s? I should think so.
He found it surprising that the Stereophoner worked at all after so long, plus my enforced meltdown. Good, British quality components. Even so, it was clear to him, as it may be to you, that the Stereophoner with one unexplained exception was nothing but a simple crossover circuit, much like thousands still used today in more modest two-way speaker systems. Instead of applying the crossover to woofer and tweeter in one speaker box, it merely sent its pair of signals right and left to spaced-out speakers.
Such a lot of fuss over nothing! The "minus" mono input being ground, the other leg was divided. The choke coil sent bass towards the "R" output, while the capacitor and resistance in series delivered highs to the "L" output. My friend's meters zeroed in at an 800-Hz crossover. The slope each way was mild, at 6 dB or less.
Nothing special at all. The variable pot, he said, served for balance, to attenuate the highs as desired.
But to his report he added one very significant item: "Does not keep good phase relationships." He wrote this first as a criticism, which would surely apply to any speaker crossover of the usual sort. Then he did a double take. As I did too, reading him.
Phasing! There, by golly, might be Dr. Scherchen's secret, neatly buried in potting gunk. For is not phasing, between several channels of info, one of the major creators of audio directionality and spatial illusion? We should not forget that the entire corpus of matrix four-channel coding and decoding had to do with highly subtle matters of phasing. Phasing, too, is of the essence in genuine live two-eared soundspace. If that simple crossover circuit was inaccurate in the phasing of its derived left and right channels, might its designers have so intended? Might they deliberately have designed in a phase inconsistency, to give an illusion of depth? And a species of directionality over and beyond the simple volume contrasts of lows emphasized on one side and highs on the other? And so the plot thickens.
I began to describe all this to my neighbor, whose mind works at the speed of light. I had no sooner got the word "crossover" out of my mouth than he bellowed "PHASING!" Instantaneous perception. He wouldn't stop for 10 minutes. Of course it must be the phasing, and he told me why in enormous detail.
So you see, maybe old Dr. Scherchen was not as simple-minded as you thought. Maybe the skimmed milk was cream? And all those authoritative 1950s listeners were not as gullible as they appear to be. There is indeed something tricky in this Stereophoner that no doubt accounts for its unusual impact as much as Dr. Scherchen's backing and the then rudimentary state of commercial true stereo.
Even if I were to give you the exact values for those three components, I suspect that you would not have a Stereophoner. (The pot was 50 ohms, the capacitor estimated at around 10 µF at 50 volts, the coil unmeasured--but if you know how, you could easily derive an 800-Hz crossover circuit of the same sort.) However, I would not want to try to analyze that phasing inconsistency's effect on the sound.
That, surely, was Dr. Scherchen's special ingredient. The original specs may exist somewhere, at Gravesano or perhaps in the files of the British-licensed firm which manufactured the 1959 "Symphony" line of hi-fi. Or you can dial Dr. Scherchen in Heaven. Betcha he won't tell you a thing, though.
I never did think I'd get to try all of Technics' Studio Collection simultaneously, and I haven't yet. But I have used the speakers long enough to know their smooth, shiny sound and to note that their angular distribution to the sides is not quite as broad as I would like for walk-around stereo. But my biggest fun has been with the ST S8 quartz synthesizer AM/FM tuner and, of course, the quartz direct-drive linear turntable described in January.
(There are other lesser models using the same linear drive principle.) I continue to be amazed at how faultlessly this table performs, considering the once-insoluble complexity of a sidewise-driven arm tracking an irregular spiral groove. And I am glad to note that its special Technics cartridge is now congruent with a number of other makes, including an Audio-Technica and an adaptation of the Shure V-15 Type IV. Please, let's keep our hard won compatibility! I caught the Technics table off-base only once, and it was all this mag's fault. The machine is so foolproof that without a thought I pulled out our Bob Carver insert record and put it on the table, closed the lid, and pushed the start. Phew! The arm moved inwards, dropped down-and played all four corners of the square, flopping wildly up and down and sidewise; I frantically pressed everything in sight, but these automatics move at their own majestic pace and it took many disastrous seconds to stop the thing. But the experience was useful. No damage to arm, cartridge or stylus. Some systems really can take it, miniaturized or not.
As for the Technics tuner, it is the first of the new breed with which I have become really intimate and it has been an experience. I began, first, with a useful comparison, my earlier Pioneer TX-9500 II, an excellent late representative of the traditional tuner with the familiar dial and tuning knob, plus meters for signal strength and channel center. Give the TX-9500 II knob a spin and it runs the whole length of the dial; mark your preferred stations where they fall, all in numerical order. This tuner has two degrees of muting and with the strongest I still could pick up some 43 FM stations with my roof antenna pointing SSW towards New York 100 miles away. With less muting, and more fuzz, I counted well over 50. There's a sort of dial on the Technics, so small you can hardly see it, but no tuning knob. Only micro-touch buttons with memory, two stations on each button, short-push and long push, which have to be programmed in, to your choice, in any old order and either FM or AM. You can make a hideous jumble, dialwise, or even tune them all to the SAME station. Crazy and wonderful. But with all those frequencies to remember, it is common sense to program in numerical order, the tiny dial serving as a rough indicator of where you are via little red LEDs.
Even this isn't too easy, because the 16 tunable channels are staggered over those eight buttons, channels 1 and 9, 2 and 10 and so on, a short push for the lower number, long push for the higher. It's zigzag at best, and I ended up tuning both channels to the same station, in case I mis-pushed.
Moreover, the fancy memory button also has two modes, short-push and long, the latter going into automatic scan, erasing EVERYTHING and setting up its own array of stations which, of course, are merely the loudest ones around. I don't know how many times I erased my entire selection because, trying to push long with one hand and short with the other, I got them mixed up. It's like driving your first time with a manual-shift transmission.
But I enjoyed the main tuning buttons, one for up and one for down or left and right. These also are short push and long. The short tunes step-by-step, frequency by frequency, AM or FM; the long runs rapidly over the "dial," coasting to a stop when you lift your finger. If your memory channel buttons are haywire, you can always find your station quickly this way, but you do have to remember its frequency.
You get the idea: Tricky. But once you learn to drive it, this is really a fabulous tuner, even on AM (which is skimpy on many tuners). The sound is terrific, the sensitivity and selectivity in practice are far ahead of anything I had previously tried and, best of all, the inevitable stereo hiss somehow is reduced to the mildest ffffff, just a velvet pur. I could pick a lot of minor criticisms and I don't much like the cybernetics, the almost invisible lettering, the long row of identical pushbuttons, the narrow eye-level readout, but I mention only that one really serious blunder--the memory button that you keep setting off by mistake. Instant erase! You can have that, thanks.
by Edward Tatnall Canby (adapted from Audio magazine, Jul. 1982)
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