Behind The Scenes (Aug. 1974)

THE ANNUAL conventions of the Audio Engineering Society are always interesting to attend, both from the standpoint of the scientific papers presented and the opportunity to see the "latest and greatest" in audio engineering equipment.

The audio industry today is a very dynamic business, and there are usually some significant new developments revealed at every convention. The 48th AES convention, held in early May in Los Angeles, carried on in this tradition.

I am going to go out on a limb and state that the BASF people have come up with one of the most provocative new magnetic tape products in some time, and one which is bound to have far reaching implications for the entire industry. With virtually no fanfare, BASF introduced the "Unisette," which is billed as a "professional 6.3 mm (1/4-in.) cassette." Picture if you will a conventional cassette, scale it up in size some 40-odd per cent, use standard quarter inch magnetic tape, and operate it at 3-3/4 ips. Now design the cassette shell so that we can have such niceties as .. . openings to accommodate erase, record, and playback heads (making possible true monitoring facilities), tape drive with one or two capstans, and two other openings which can be used for tape tension control. the BASF Unisette has all this and more. For example, instead of tape guidance being carried out in the cassette itself, as is the case with our present minicassettes, which is said to be "disadvantageous" to azimuth as well as wow and flutter, tape guidance in the Unisette is exclusively controlled by the machine. In the words of BASF, "when the Unisette is placed in the machine, those parts which are in contact with the tape, are automatically put in the correct position by the machine. These parts are the two roller guides and the two hubs. The accuracy of the tape guidance is adjusted on the machine and remains invariable for all Unisettes used." Other features of the Unisette include a "hub brake," which automatically locks the hubs when the unit is not on a machine, thereby preventing tape loops or loose tape, and two nonmagnetic metal plates to protect the tape wind, so that no layers will come off during transport or from rough handling. As in conventional cassettes, there is provision to prevent accidental erasure. Recording on both sides of the Unisette at 3-3/4 ips, regular 1/4-in. long play tape gives a total time of 30 minutes; double-play tape gives 40 minutes, and triple-play tape 60 minutes.

Needless to say, inclusion of a two speed motor in a machine will permit operation at 1-7/8 ips with subsequent doubling of recording time.

At this juncture someone is bound to say that the Unisette is interesting, but haven't we traveled this route before? Indeed we have; some 12 or so years ago there was an ill-fated attempt by RCA to market a somewhat larger "cartridge" which used 1/4-in tape and ran at 3-3/4 ips. What happened? Perhaps the time was out of joint, and it was an idea that came too soon. Perhaps a technical problem was contributory .. . remember, this was pre-Dolby, and there were no fancy low-noise, high density tape oxides, etc. In any case, it never got off the ground.

BASF feels that the Unisette has particular application for automated radio programming, professional portable recorders, high quality audiophile recorders, language laboratory machines, etc. It is obvious that all the technology that has been lavished on the minicassette is equally applicable to the Unisette. I talked with one of the Unisette project engineers at the BASF exhibit, and in his technical manual he showed me the track layout for quadraphonic sound ... four channels "in-line," single pass from supply to take-up hub.

Using Dolby B noise reduction and with the track widths about the same as used on reel-to-reel quadraphonic recorders, signal-to-noise ratio should not be a problem. Okay, you say ... the Unisette sounds like a dandy idea, where do we go from here? For once it looks like there will be relatively quick action in getting this kind of product to market. None other than the prestigious Willi Studer is reported to be readying a Unisette recorder to be available in the fall of this year with a projected price somewhere "between $450-$500." (I think that may be a bit low, but no matter.) Negotiations are also reported under way with Sony and TEAC to produce Unisette recorders. It all sounds very enticing, and at the moment I'll do my best to keep you informed on new Unisette developments, and leave the pros and cons on this new concept for a future time.

My head still full of the intriguing possibilities of the Unisette, I wandered into another of the AES exhibit areas, and at the Haeco booth, in all it's shining glory and precision, was a fully operating Scully disc recording lathe.

Beautifully indeed, but nothing new here. But hold on a second ... I hear Haeco president Howard Holzer explaining to a visitor that all the variable pitch and depth automation on the Scully is operating without any signals from an advance (preview) head! How can this be? As you probably know, in the usual disc-cutting set-up, whether it be Scully or Neumann, the tape passes over an advance magnetic head, which tells the logic automation on the lathe what to expect from the program signal, and gives the logic time to act on this information. For example, if a triple fortissimo passage of music passes over the advance head, the logic "knows" that it must open up the lines-per-inch control and adjust the variable depth control to accommodate this high level signal. If in the next second a pianissimo passage is encountered, the reverse holds true and the lines-per-inch can be increased. Naturally, music consists of many complex waveforms at varying dynamic levels, and so the advance head furnishes the lathe logic the information it needs to operate on this same dynamic basis. This system is the reason that in recent years we can get better than 30 minutes on one side of an LP, with little or no reduction in level or in bass response. I have oversimplified this a bit, and should have mentioned that any equalization, filtering, noise reduction, limiting or other signal processing equipment that the program signal is going to pass through, must be duplicated for the advance head signals so that the lathe computer gets the correct information.

Now back to the Haeco booth ... there is indeed no advance head in this disc cutting set-up, and Howard Holzer proudly introduces me to his new brainchild, the Haeco VP-1000 digital lathe control system, occupying a mere seven inches of rack space. Our clever friend has designed a 15-bit stereo digital delay line which provides a 300 millisecond delay of the program signal. In other words, the lathe control circuits receive the identical signals as the cutting system. As Howard puts it .. . "any minute change made in the program channel is automatically (seen) by the lathe 300 milliseconds prior to the cutting transducer." Howard pointed out that one of the advantages of his VP-1000 unit was that duplicate signal processing equipment used as part of the advance head system is eliminated. He also said that with his digital system, more time than ever will be able to be cut on a disc, since groove geometry is now completely governed by the recording level. He further stated that lines-per-inch and depth changes are made only as required by the program material with variable pitch information updated every 15 milliseconds and variable depth.

information every 100 milliseconds.

Coming on the heels of the Neumann SAL 74 computer cutting system I reported on in the June 1974 issue of Audio, the Haeco VP-1000 is further proof of the vitality of the venerable phonograph record and the continual updating of disc cutting technology. One absolutely intriguing aspect of Howard Holzer's new device is its application to direct disc recording. You have probably heard about the Sheffield Record Co. in Los Angeles which has issued a series of three recordings in which the output of the studio mixing console is fed directly into the cutting amplifier. Obviously since there isn't any tape, there isn't any advance tape head, and thus there is no possibility of lathe automation as far as variable pitch and depth are concerned. This is a handicap, and it is a tribute to the lathe engineer that he does so well and achieves a stunningingly clean and dynamically exciting recording. Nonetheless, with a potential 80-dB dynamic range on a direct-cut lacquer, with the Haeco VP-1000 able to provide lathe automation, more of this great range can be realized and the result would probably be utterly spectacular.

While the Unisette and the Haeco units were outstanding items at the AES convention, there were, of course, many other interesting developments.

In the quadraphonic area, JVC and Panasonic (Technics) both had operating CD-4 demonstrations in which they used their long-anticipated IC-chip demodulators. These prototype units were less than a third the size of their present demodulators and on a rather superficial hearing, each seemed to do an exemplary job presenting nice, clean, well-separated quadraphonic sound. The JVC and Panasonic chips are both made by Signetics, but the engineering approaches differ. The JVC chip is the product of their engineering group, while the Panasonic chip was designed by Lou Dorren of QSI. I expect to be testing one of these IC chip demodulators before long. At the Sansui exhibit, they were once again demonstrating their QS variomatrix, this time with a splendidly atmospheric and fascinating recording of the recent royal wedding of Princess Ann and Captain Phillips. Nippon Columbia is evidently solidly behind Duane Cooper's UD-4 carrier/ matrix quadraphonic disc system, as they have announced they will be making demodulators and software available by this fall. So we will have to wait until then, to put this system into perspective with the competing quadraphonic systems.

BGW Systems, manufacturers of a number of high-powered amplifiers, including a new quadraphonic unit of 4 X 150 watts per channel (!), was showing an impressive looking quadraphonic pre-amp with a multitude of controls for versatile signal processing.

Price is reported to be "around $800." Mark Levinson was on hand with his superb standard LNP-2 pre-amp, I reported on some months ago. Now he has a new pre-amp, with simplified controls and less facilities, but the basic specs and the overall quality are the same as in the LNP-2 at a little more than half the price.

Affable Clyde Moore of Crown International was on hand with his new M600 power amplifier, busily lighting up 600-watt light-bulbs, which as the visual purple in my eye told me for a long time afterwards ... are very bright indeed! Also on hand, a neat looking prototype of the new Crown electronic crossover, intended for us with Crown's electrostatic hybrid speakers and similar applications requiring bi- and tri-amplification.

Everywhere you looked there were professional tape recorders. As might be expected, pride of place at the Ampex exhibit went to their new model 440C. 3M and Scully had their top-of-the-line machines on hand, MCI created a lot of interest with their recorders which are now well in production. Studer, striking out on their own leaving the fold at Gotham Audio, was showing a huge 24-channel unit, as well as their well-known 2- and 4-channel units.

With the establishment of several regional offices across the country, Studer will evidently take a more active role in the American market.

Gotham Audio has, in turn, taken on the German Magnetophon, which claims exceptionally low wow and flutter specs.

As is usual, there were ever more complicated mixing consoles, with enough controls to frighten a 747 pilot.

And there were new digital delay units, and equalizers, and ... well, you name it. I could fill up many pages with descriptions of worthwhile recording or measuring equipment. If anyone feels slighted, my apologies.

So went the 48th AES convention and with any sort of luck I may recover in time for the 49th convention at the Waldorf-Astoria in New York ... come September.

--Bert Whyte

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(Audio magazine, Aug. 1974)

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