Behind The Scenes (July 1970)

Bert Whyte

I had hoped to give you a report on live recording of four-channel stereo, but have had to shelve the project temporarily.

Not from lack of equipment or anything like that, but for the more basic reason of lack of co-operation among the parties involved. Not to worry . . . I've gone through this sort of thing before in the early days of stereo, and these problems will soon be resolved.

There has been considerable activity on the four-channel front, some of which is quite significant. I think that even the most enthusiastic advocate of four-channel sound would have to admit that in the general hi-fi scheme of things, this "new sound" has had relatively little impact on the status quo. There are those who say that four-channel sound is largely a promotional gimmick, something that given time might catch on with the affluent audiophile. There is certainly an element of truth in this, but a recent development is about to change the entire four-channel picture.

As noted elsewhere in this issue, RCA has decided to exploit four-channel sound in a big way. What was an esoteric development and the plaything of the audio avant garde, has suddenly become a product, which will be promoted with all the power of mass merchandising. It is interesting that RCA is the company involved, sort of like history repeating itself, since they were the first major company to issue two-channel stereo tapes in 1954 and that really started the stereo boom. I do not mean in any way to denigrate the pioneering efforts of Vanguard. They were first in the field and deserve much credit for the courage of their convictions. And I am sure we will see more forward-looking developments from this enterprising company. However, it is obvious that a company like RCA has the money and the means necessary to make four-channel sound a viable entity in the field of consumer stereo. Let us take a brief look at what RCA has developed.

We can guess that some smart lad took a good look at an RCA Stereo 8 cartridge and the light suddenly dawned that here was a quick and easy way to provide four-channel sound ... to wit: instead of four two-track stereo programs, the same eight tracks could accommodate two four channel stereo programs. This is just exactly what RCA has designed. Thus they have ready for marketing this fall what they call the YZD-400 four-channel sound system. This consists of what appears to be a conventional 8-track cartridge player, mounted in a cabinet with self-contained speakers to the left and right of the player unit. However, the player has a four-channel head and four amplifiers and two external speakers are provided which plug into the player unit to furnish the rear audio channels. Left/ right balance controls are provided for front and rear speakers and there is a ganged volume control to raise or lower the level of all four channels. The four channel cartridges which RCA has dubbed "Quad 8" look like the conventional 8 track variety, but use slightly thinner tape. These Quad 8 cartridges will provide up to 25 minutes of music on each of the four-channel programs, thus making them roughly equivalent to the playing time of the average LP record. This matter of playing time puzzles me somewhat. In standard 8-track cartridges you can get up to 80 minutes of playing time. One would assume that with the use of a thinner tape, even more playing time would be provided. Since the four-channel head will shift from one four-channel stereo program upon it's conclusion, to the second four-channel program (on the endless tape loop basis) there would not seem to be any technical reason for the overall playing time to be less than that of the standard 8-track cartridge. I suppose we will know the reason for this before long. In any case, if a total of 50 minutes is the limit, certain music like some of the Mahler symphonies and most operas would require more than one Quad 8 cartridge. The new Quad 8 player is completely compatible with present 8 track cartridges. Initially, the player unit will have a "mode adjust" button, which selects either four-channel or conventional two-channel stereo. It is hoped that eventually a "sensing slot" can be molded into the cartridges which would allow the player to select automatically either two channel or four-channel stereo modes of operation.

Now here is a quote from RCA which has hidden significance: "Players will have left front and rear, and right front and rear speakers with completely discrete channels for each. The new dimension of realism is thus achieved without sacrifice of conventional stereo separation." At this time there are a number of quadraphonic systems in being which employ various methods to produce four channels of sound which differ from the original four-channels-in-line on tape as used by Vanguard, for example. At this stage of development, it would not be fair to reveal which process was involved, but this particular one was demonstrated to RCA and obviously on the evidence of the Quad 8 development, was rejected. One of the criticisms most often leveled at these systems, is reduced stereo separation, which apparently is why RCA makes a particular point about their "conventional stereo separation." The four-channel stereo systems I have been using in my home costs thousands of dollars. Thus it is slightly shocking to find out that the cost of this RCA YZD-400 Quad 8 is $199.95. Obviously with small speakers front and rear and low-powered amplifiers, one doesn't expect a very opulent sound. Nevertheless, it will be interesting to hear to what extent the four-channel stereo aids the sound we normally expect from such inexpensive equipment. More to the point is the fact that four-channel stereo is being offered at a low price to the mass market. The ramifications of this are enormous, and unquestionably this development is reshaping the thinking of many in the industry. One thing seems reasonably certain . . , in one format or another, four-channel stereo is no longer the exclusive province of the audiophile and it looks as though it is here to stay.

Presumably RCA will eventually offer their four-channel player in deck form, and this, combined with amplifiers and speakers of good quality, will receive the attention of many audiophiles. As to RCA four-channel repertoire, they have been recording in this mode for many months now and have built up a catalog of some 25 titles ranging from "Hair!" to the Mahler 2nd Symphony with Ormandy and the Philadelphians. All of their recording is now done in four-channel stereo, so the catalog should build up quite rapidly. This being so, one can surmise that when circumstances dictate, RCA could move quickly into four-channel cassettes and in whatever form the four channel disk finally appears. May I respectfully suggest to RCA that the oft maligned but quality-conscious audiophile is still the man responsible for this entire hi-fi industry. Give him a break. Do as you did in 1954 . . . issue your four channel stereo on open-reel tape. It is just as easy, in fact more so, than your new Quad 8 cartridges. Why not go whole hog and issue them in "Dolbyized" form as well? You'll get a very grateful group, who will broadcast your message everywhere with typical audiophile fervor.

In a parallel development, Motorola announced it was building automobile players for the RCA four-channel stereo cartridges, that they had already demonstrated the system to major car manufacturers, and that it was expected to appear in some 1971 and 1972 models.

Cadzooks! To use a well-worn cliche, the mind boggles. One must assume that virtually all four-channel car tapes will be of the pop variety, because the high noise levels of the mobile environment would swamp the rear reverb of classical productions. In any case, this is but one more indication that things are moving very rapidly in the four-channel field and it can no longer be dismissed out of hand as a mere gimmick.

You know, in this audio business you can never take anything for granted. Or assume that if a problem is solved, it stays solved. A good case in point is this business of spherical versus elliptical styli. Over the past few years it has been generally assumed that the elliptical styli tracked better and produced less distortion, especially at the inner grooves, than it's spherical counterpart . This was held to be true even with records cut with a stylus correlator, which meant RCA records since the correlator was used only by them as part of the original "Dynagroove" process. Incidentally, for many years now, the only part of the "Dynagroove" still used is the stylus correlator.

While the name still appears on RCA records, it is no longer meaningful. Now it appears that some of our diligent researchers and theorists have come up with new information which seems to reverse the present ideas about elliptical styli. Although all the research is not yet conclusive, it would seem that better tracking and less distortion are obtained with spherical styli of 0.7 and 0.5 mil radius.

They are even experimenting with 0.35 mil styli! If mention of the "half mil" stylus seems to ring a bell, you may remember that spherical styli of that radius were considered the last word in the later days of the monophonic cartridge. At any rate, I am being sent some 0.7and 0.5 mil styli and we will have a listen. These same researchers are upsetting other apple carts too ... For example, in the matter , of skating-force adjustment, which is a feature of most modern arms, you are told via a chart that at X stylus force, you should dial in X skating compensation.

All well and good . . . except that our friends have determined that the various á record companies use varying types of vinyl compound to press their records.

These differing types of vinyl have different co-efficient of friction, thereby invalidating any so-called standard setting. But take heart, there are still those engineers who pooh-pooh the whole idea of skating compensation. In fact, as one engineer friend of mine who is quite prominent in phono cartridge research said recently . . ."you can prove that cartridges and records have all kinds of distortion, but most of it is in fairly exotic areas and if you take care to eliminate or reduce the most basic distortions, the ear can happily ignore all the rest." My friend went on to say that the "basic distortions" in many cases can be traced directly to poor installation of arms, especially as regards correct positioning between the turntable spindle and the arm pivot, and the correct turntable/arm height adjustment. He also pointed out that when cartridges are installed in arms, the slightest deviation from true perpendicularity to the record surface can aggravate several forms of distortion. Finally, the thing he deplores most is the fetish of super-light stylus forces. In a certain few arms, he said, they can operate successfully at one gram or less. For the rest, he says that more distortion is produced by the stylus rattling in the record groove at excessively light forces than all the rest of the arm/ cartridge distortions put together.

(Audio magazine, July 1970; Bert Whyte)

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