Behind The Scenes (Dec. 1974)

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THE THIRD act of the Audio Engineering Society road show, otherwise known as the 49th Convention, opened on September 9th in its usual venue, the Waldorf-Astoria in New York.

As in past years, the ballroom of the Waldorf was crammed with exhibits of the sleek, glittering equipment of professional audio engineering. As usual, manufacturers who offer active demonstrations of their products were ensconced in rooms on the fifth floor. The papers presented at the various sessions were as informative and interesting as ever and, for the most part, well attended. New at this convention was a series of four seminars: "Introduction to Programming for Desk-top Computers," "Application of the Desk-Top Computer to Audio Engineering," "Tape Recording Alignment-Why, What, and Where," and "Practical Studio Acoustics." In other words, the usual ingredients for a successful AES convention were on hand. Yet I couldn't help feeling that the show was a bit subdued ... rather low key. Maybe it was a reflection of the depressing times in which we are living. Perhaps it was due to the fact that there wasn't as much new equipment nor new ideas, as we have come to expect at the AES conventions. In any case, whatever it is that gives a show "pizazz" was a bit diluted.

Which is not to say that there weren't some highlights, and some very interesting items. It would be a very rare AES convention indeed that was totally bereft of provocative ideas and innovative equipment! In my report on the 48th AES convention, I singled out the new BASF "Unisette" 1/4-in. tape cassette and Howard Holzer's digital cutting-lathe control system as very significant advances in audio technology. Those who had somehow missed the introduction of the "Unisette" concept in Los Angeles were given the full run-down on the system in a paper presented by Klaus Goetz of BASF. It appears that Willi Studer will still produce the first recorders that utilize the "Unisette," however, I have been told that the introduction of these units will be somewhat later than anticipated, with a good guess being late Spring of next year. It would also appear that the original cost of the recorders, stated as being "around 400 dollars" was extremely optimistic.

I could not elicit any further information as to the "Unisette" activities of Sony or Teac. Nothing really surprising about all this . "start-up time" is usually a problem with most new audio products. With an idea as exciting as the "Unisette," you can be sure I'm going to watch its development very closely.

At this convention Howard Holzer was to have presented a paper on his "Advance Headless Variable-Pitch/ Variable-Depth Lathe Control System." I am very sorry to report that Howard was killed in a private plane crash in Mexico, several weeks before the convention. This tragic accident has deprived the industry of a most dynamic man with one of the keenest minds in disc recording technology. Howard's son Mark presented his paper, and I understand will continue the operation of Haeco.

Although I am not certain of all the facts, I believe that Atlantic Records, here in New York, has, or will shortly install, the first of the Haeco (Howard Holzer's company) digital-delay cutting systems. I look forward to hearing some Atlantic discs cut with this clever, new system.

A number of interesting new items were being demonstrated in the sound rooms on the fifth floor. For example, old friend and audio pioneer Rudy Bozak was showing off a new speaker system designed for high-output Rock-music enthusiasts.

In an enclosure roughly twice the size of his well-known 302 system, are mounted four 8-in. speakers of a new design, which crossover about 2500 Hz, where a curved array of light 2-in. tweeters carries on up to the high frequencies. Rudy has also entered the consumer amplifier market with a husky 150-watt-per-channel unit. The new speaker, driven by this powerful amplifier really puts out a lot of loud, but very smooth and clean sound.

In the North American Philips room they were demonstrating their amazing little motional-feedback loudspeaker, along with the Model 209 electronic turntable. Also on display were a wide variety of AKG microphones, which they represent in this country, as well as the new BK 20 AKG professional reverberation unit. I recently visited Philips in Eindhoven and AKG in Vienna, and it was a fascinating and most educational experience. I will report on this trip shortly and discuss the above mentioned products in detail.

In the Panasonic/Technics room they were demonstrating the new IC-chip demodulator. This is the IC developed by Lou Dorren of QSI and made by Signetics. Rather surprisingly, the new SH-400 demodulator is larger in size than the present discrete SE-405 unit. John Eargle, the newly installed President of the Audio Engineering Society, visited with me the weekend before the Convention and brought one of the new SH-400 demodulators with him.

(John's JME Associates consulting firm has most of the CD-4 people as clients). We played around quite a bit with the unit and the quality, separation, and the sheer "discreetness" of the music on a wide variety of CD-4 recordings was truly outstanding. All that fancy new circuitry obviously makes quite a difference! A full report on this new IC demodulator will appear soon.

At the Nippon Columbia demonstration room, Prof. Duane Cooper (new President-Elect of the AES) was showing off the versatility of his UD-4 quadraphonic disc system. Mono and stereo compatibility was emphasized, and then a recording would be switched progressively through the matrix modes and finally to four channel discrete. Very impressive, and it now appears that of all things, the UD-4 system with software and demodulators, will have its first public outing on the English market.

I had the pleasure of meeting Dr. Takeo Shiga, Director of the Acoustical Products division of Nippon Columbia, and Takayasu Yoshida, Deputy Gen. Mgr. of the International Trade Division. Dr. Shiga has visited the U.S. many times and has been frequent contributor to the AES Journal. A man of wide technical attainments, at this 49th Convention he was awarded the Silver Medal of the Audio Engineering Society at the presentation banquet. I had a most interesting conversation with these gentlemen, and learned that Nippon Columbia has a digital tape recorder and has actually made some commercial recordings with the unit. I have been promised some of these PCM (Pulse Code Modulation) discs and I am agog with anticipation! If the "Unisette" and the Haeco lathe control unit were the outstanding new items at the 48th Convention, a new development from Pioneer Electronic of Japan must be reckoned as the most important item at the 49th Convention.

Four engineers from Pioneer's Acoustical Engineering Research Laboratory presented a paper entitled "Electro-Acoustic Transducers with Piezoelectric High-Polymer Films." The term "piezoelectric" has heretofore been in the audio vocabulary as applied to cheap low-fi phono cartridges utilizing ceramics such as Barium titanate and crystals such as Rochelle salts and quartz. Recently we have had the high quality piezoelectric tweeters produced by Motorola and, in fact, there was also a paper concerning them at this Convention. What the Pioneer engineers have discovered is that a high-polymer film of poly (vinylidene flouride) has piezoelectric properties, with a piezoelectric strain constant almost ten times greater that that of quartz.

Evidently research into the piezoelectric potentials of various substances has been going on for quite a while. Russian workers found that wood had piezoelectric properties in the 1940's. In the 1950s highly crystalline biological substances, such as collagen, bone, and silk, showed piezoelectric qualities. In 1959, a biological high polymer, such as whale bone and tendons, were actually used in a phono cartridge! Poly (vinylidene fluoride) is a fluorocarbon resin. The process which renders piezoelectricity to the high polymer is described in the Pioneer paper ... "The films (8 to 30 microns depending on their applications as transducers) are uniaxially stretched up to four times the original length at 60-100°C. Then aluminum is evaporated on both sides of the film as electrodes. The films are then polarized with a high d.c. electric field at 80-100°C for about 1 hour. The process is similar to that used for piezoelectric ceramics. When a high a.c. field is applied to the film, a hysteresis loop between the applied field and the polarization has been observed." The piezoelectricity of the film is quite stable even at 100° C, and it is not affected by moisture or dust.

In essence, this Hp (high polymer) film involves the transducing functions in themselves. The application of a.c. makes the film vibrate in a transverse direction and when the film is curved, the vibration is transformed into a pulsating or "Breathing" movement. Obviously this sort of diaphragm can be used as transducers in such things as headphones, loudspeaker tweeters, and even phono cartridges and microphones. At a room upstairs in the Waldorf this amazing film was being demonstrated. The first commercial application is in the form of Pioneer SE-700 High Polymer stereo headphones.

These $80.00 phones weigh in at only 13 ounces and are extremely comfortable to wear. With their HP diaphragms, they can be plugged directly into 4-16 ohm headphones jacks on receivers or amplifiers. They are quite sensitive, 3 volts giving 100 dB SPL. They can take inputs up to 30 volts and 120 dB SPL without clipping.

The sound was very wide range and smooth, akin to the best electrostatic phones. Also being demonstrated was a loudspeaker of the column type, with downward firing woofer. This crossed over to a circular "mid-range" HP film unit operating from 2 kHz to 7 kHz, where a smaller

cylindrical tweeter carried on up to 20 kHz. The pattern of the two HP units is truly omni-directional. The sound is characterized by extreme smoothness and excellent transient response. We were also shown non working models of a mike and a phono cartridge. I spoke to Dr. Takeo Yamamoto, Pioneer's Director of their research lab, and he stated that the HP diaphragms could just as easily be direct-radiator types as well as the omni-directional type on demonstration. When I asked him about the feasibility of making up say 4-by-4-in.

panels of the HP film in multiples, a la RTR, Crown, and some other electrostatic speakers, which would permit high output with very low distortion and full frequency range without crossovers, he indicated it was just a matter of implementation. Certainly this HP material opens up whole new avenues of experiment in areas where light mass and low mechanical stiffness and the self drive of piezoelectricity can be applied to transducing functions.

Next AES convention will be the "Golden Fiftieth," and will be held at the Cunard International Hotel in England during March of next year.

I see by the calendar that this is the Christmas issue, and I have a jimdandy of a present for anyone who owns tape recorders and does any sort of editing. This is a new kind of tape splicer made by Nagy Research Products, Box 289, McLean, Virginia 22101. If you've ever tried to cut mylar tape with the usual single-edge razor blade, you know how tough mylar can be. It can wear out blades very quickly. Mr. John Nagy uses the same dove-tail splicing groove to hold the tape as in the familiar Editall units.

But ... his blocks are equipped with stainless-steel, self-sharpening shears.

Remember to keep a bit of pressure to the left side of the lever type shear and the Nagy will cut the mylar cleanly and as easily as a hot knife through butter and sharpen itself at the same time. The simplest Model 6S25, is $16.95, the more elaborate Model 25STS with a splicing tape dispenser costs $24.95. The one I have is the top of the line TS-250 and it is a real beauty. It has the tape-cutting shear, then a splicing tape dispenser mounted on a hinge, and when the desired length of tape is pulled from the dispenser, then the assembly swings down on the hinge and positions the splicing tape precisely on the two pieces of tape you want to join.

Now this is hard to visualize, but there is yet another cutting shear that cuts the splicing tape and through the ingenious design does not cut the magnetic tape. It all works much easier than this description. With it you get professional quality splices with an absolute minimum of fuss.

At $49.95 this is a super gift for the tape recorder buff.

(Source: Audio magazine, Dec. 1974; Bert Whyte)

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