Behind The Scenes (Dec. 1973)

by Bert Whyte

THE AUDIO ENGINEERING SOCIETY must have influence in "high places." The annual New York convention of the Society was held earlier than usual this year, settling in at the Waldorf-Astoria on September 10th, and just missing a steamy, debilitating 10-day heat wave, with its concomitant power brown-outs.

This 46th convention of the Society was the third and final one of the year, a fact that was greeted in certain quarters by sighs of relief. For the doughty technicians and engineers of the various exhibitors, charged with the responsibility of setting up a properly functioning display and then tearing down and repacking everything, it has been a "long, long trail a-winding" from Rotterdam, to Los Angeles, to New York. As usual, the Grand Ballroom of the Waldorf was jam-packed with every conceivable kind of audio equipment.

Some of the gear had been seen at the earlier conventions . . . after all, one doesn't design a new mixing console every other day! But there were plenty of interesting new items. DeWitt Morris of United Recording Electronics Industries was on hand to show us the production models of their Electronic Crossover Systems. These are active crossover networks on plug-in cards.

Crossover frequencies are continuously tunable ... the 521-L from 200 Hz to 2 kHz, and the 521-H from 1 kHz to 10 kHz. Filter characteristic is 2-pole Butterworth yielding 12 dB per octave.

The cards plug into either the 521-P chassis with internal power supply or the 521-E for external powering. Cards can be combined so as to give bi-amplification, tri-amp (3-way), or four-way amplification. There is currently a revival of interest in multi-amp speaker systems. Many people are experimenting with exotic low frequency systems, such as transmission line, corner horn huge infinite baffles with 24or 30-in. drivers or outsize acoustic suspension systems. These are being combined with various electrostatic and dome-type tweeters.

The various levels of efficiency between the low and high frequency units dictate bi- and tri-amplification and hence the need for a good electronic crossover network. I expect to have one of these new UREI units before long, for use in some fairly exotic speaker configurations I have been pondering for some time.

Two new tape machines in the "advanced audiophile"/semi-professional category made their debut at the convention. One from Revox was the long-awaited successor to their A-77 model. The machine had arrived just a few days prior to the show and there wasn't even literature available, so details are a bit sketchy. It has a very advanced servo-motor drive system which I gather is of the crystal-controlled reference oscillator type. A "fail-safe" logic tape-handling system is a feature as is an integral four input mixer. The tape drive is of the closed-loop type. There are much larger VU meters than on the A-77 and I believe there are peak "hold" facilities. While the present machine is available in quarter- and half-track stereo in normal and high speed (7 ½, 15 ips) versions (there is no quadraphonic unit as such), it would appear that conversion to this format at some time in the future could be easily accomplished. The new Revox is expected to cost around $1,800, and as soon as we get more details and/or a unit to play with, we'll bring you up to date.

The other new tape machine is the British-made Ferrograph Super Seven. This 10 1/2-in. reel machine has a host of features, some of them quite unusual. It is a three-motor/three-speed/three-head unit with variable speed on fast forward and rewind to eliminate over-tight tape wind. It has, of all things, electronic editing! To quote Ferrograph, "no clicks, no pops, new material replaces old without annoying bias transient noises." If this is what I think it is, this would seem to be a "first" in an audio tape recorder. Heretofore, electronic editing has been found only in super-expensive video tape machines.

Among other goodies, there are pushbutton bias readings, automatic demagnetization of tape heads, and this I have to see . . . endless-loop cassette facilities! To further gild the lily, Dolby B-Type noise reduction is optionally available for a nominal $125.

The Ferrograph Super Seven is available in quarter- and half-track stereo at 1 7/8, 3 3/4, and 7 1/2 ips, or in the high speed version 3 3/4, 7 1/2 and 15 ips at no extra charge. Price with Dolby B is $1075.00. Speaking of Dolby, at their booth Ray Dolby showed me his new Cinema Equalization unit. Dolby noise reduction for use with motion picture optical tracks is an ongoing thing. It is a project which takes time, but new developments are hastening the day when Dolby encoded prints will be industry standard. The object of Dolby noise reduction with film is not an improvement in the signal-to-noise ratio in the movie house as audience noise would swamp the 10/15 dB Dolby reduction. For many years motion picture sound tracks have been saddled with restricted frequency bandwidth.

There exists the "Academy" or Cinema Equalization Curve, which is supposed to give a bandwidth on optical tracks from 50 to 7500 Hertz. In actual practice, they are lucky to get 80-4000 Hertz.

The reasons are numerous, a combination of the optical recording process, the type of film stock, and film development techniques. Even with modern film stocks of fine grain, high resolution, and super high acutance developing chemicals, the cumulative noise still restricts the bandwidth. The use of Dolby noise reduction allows optical tracks to achieve a frequency response from about 40 to 10 kHz. This gives a less distorted, far cleaner sound with better articulation in dialogue, more natural sounding music, and more dramatic special effects (low frequency cannon fire in battle scenes, more realistic thunder). The print must be released in the Dolby "compressed" (encoded) state and in the theater played back (expanded, decoded) through the special Dolby Cinema noise reduction module. Of course, most theater sound systems are set up for the old Academy curve. The purpose of the new Dolby equalization module is to adjust the theatre sound system to the characteristics of the Dolbyized optical tracks. According to Ray Dolby, over 100 movie houses in England have installed his noise reduction modules, and there are a half-dozen films now shooting in England that will be released as Dolby prints. Film executives and engineers in this country have been impressed by a number of Dolby film demonstrations and hopefully it won't be too long before we can enjoy this improved sound in theaters in this country.

In the Waldorf ballroom, New York engineers had their first look at the imposing new 3M Series 79 tape recorders available from mono all the way up to 24 tracks. Ampex was on hand of course, and I had a fascinating demonstration of their synchro-lock system. A color TV monitor showed a picture played back from the new Ampex 7900 video tape machine. A 440 servo recorder furnished the audio track for the picture. Through headphones, you could hear the audio master in your left ear and the recorded track from the video machine in your right ear. You watched the picture for lip-sync. No matter how wildly the video recorder was deliberately started out of sync, a touch of a button on the synchro "black box" would snap picture and sound into perfect sync.

You could start the audio master late, but no matter ... sync was established in a twinkling.

A lot of action on the fifth floor of the Waldorf where the sound demonstration rooms were located. Here was where the quadraphonic action was.

Sansui had an elaborate set-up to demonstrate their new Vario-Matrix IC chip. They are claiming 12/15 dB of separation with this chip with possible expansion to as much as 20 dB. The A/B comparisons between master tape and decoded disc were impressive and certainly seemed to support their claims.

Columbia, not to be outdone, was playing their SQ discs through their new IC chip, which I believe combines full logic plus "variable blend." This latter addition has virtually eliminated the rear channel "pumping" and "breathing" of the earlier matrices to which some people objected. What I heard was nice clean four-channel, but I think some better records could have been chosen to demonstrate this advance.

JVC was, of course, playing CD-4 discrete discs, including some of the new Elektra titles. Separation was beyond cavil, but the sound could have been of better over-all quality had they used some higher quality loudspeakers.

They were once again showing their fascinating and unique MM-4 peak and VU level meter for quadraphonic sound utilizing a "plasma film." I gave a more detailed description of this meter in my Los Angeles AES report in the August issue. It seems production on this unit has been delayed, but I still hope to have a unit for test in the next few months.

Mark Levinson had a room in which he was demonstrating his super pre-amp (of which I spoke last month) along with his JC-1 cartridge pre-amplifier.

Mark was sharing his room with Jon Dahlquist, who was demonstrating his new model DQ-10 "Phased Array" loudspeaker. The speaker at first glance looks like the British Quad electrostatic unit, but in the rear is a good-sized bulge, which I would assume acts as the woofer enclosure. The speaker is a four-way dynamic system using five drivers in an acoustical configuration which is claimed to provide on-axis compensation for time-delay effects.

The speaker is stated to have a response from 32 to 25 kHz, with very low IM distortion and wide vertical and horizontal dispersion. Big claims indeed, but the speaker has made a considerable impression on many people, not the least of whom is Saul Marantz who has gone into partnership with Jon Dahlquist. In the limited time I listened to the speaker, I found it exceptionally smooth, with really good transient response, a bass response hard to believe from such an odd configuration, and good stereo imaging. In short, a very clean, natural sound remarkably free of coloration. In due time, I hope to have a pair of these speakers at home for more of an insight into such areas as power handling, etc.

In the Gotham Audio room, president Steve Temmer proudly showed me the new EMT 424 Flutter Analyzer. This fabulous instrument is the last word for really nailing down tape motion parameters. It is much too complicated to explain everything, but among its features is a memory hold on the meter, so you don't go nuts trying to figure a value. There is an automatic analyzer section which scans the entire frequency range between 1 and 100 Hz in 20 seconds. The results can be seen on a graphic pen recorder or on a memory oscilloscope.

At Burwen Laboratories room, Dick Burwen was playing a recording of Mahler's 3rd Symphony made with his noise eliminator system. Very clean sound indeed. He was also showing his dynamic noise filter. I have had one of the filters at home for a while and it is a unique and interesting item on which I will report in the near future.

All in all, the 46th AES convention was a success. Many important papers were given, especially some on digital recording. The convention was also a good scene for some AUDIO Magazine people, past and present. This was the 25th anniversary of the AES, and former Editor and Publisher C. G. McProud, a charter member of the AES, was guest speaker at the banquet. Our own Ed Canby was made a Fellow of the AES, a long overdue reward. Also made Fellow was old friend and associate Bob Fine. Dick Burwen was similarly honored. My dear friend Murray Crosby, "Mr. Multiplex," having already been made a Fellow, was awarded an Honorary Membership.

Needless to say, Jack Mullin's fabulous collection of historical recording equipment was as big a hit at the Waldorf, as it had been at the Hilton in Los Angeles. Thank you, Jack! Well, that is the AES convention activity for 1973. Perhaps we will recover in time for the Copenhagen 47th convention in the springtime!

(Audio magazine, Dec. 1973; Bert Whyte)

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