Behind The Scenes (Aug. 1979)

Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshooting

The annual Los Angeles convention of the Audio Engineering Society was later than usual this year, May 15-18, and unfortunately coincided with the gasoline shortage hysteria that swept California. While the 63rd AES Convention was bigger than ever, and set new records for the number of exhibitors, the gasoline crunch kept the attendance at about the same level as last year.

Just prior to the convention, May 1113, UCLA Extension, in cooperation with the AES and Audio magazine, presented a seminar on "The Revolution in Home Entertainment: New Technology's Impact on the Arts." Chaired by Martin Polon, Director of Audio-Visual Services at UCLA, who was also the Chairman of the 63rd AES Convention, this symposium suffered a reduction in attendance as a consequence of the gasoline problem.

Nonetheless, there was quite a respectable turnout, with the attendees ranging from engineers of the audio manufacturers, salesmen from audio retailers, inquisitive audiophiles, and even Wall Street analysts. Everything from digital recording through direct disc to the latest developments in speakers, amplifiers, tape technology, all aspects of video, laser communication, and satellite broadcasting. Finally, "Visions of the Year 2000" was presented by a panel of speakers which included Dick Heyser; John Eargle; Bart Locanthi of Pioneer Development Laboratory; Stan Ricker of JVC Cutting Center; Emil Torick, former President of the AES and a Director of the CBS Technology Center; Jeffrey Krauss of the FCC; Bruce Apar, Editor of Video magazine; John Dykstra, supervisor of special effects for "Star Wars" and producer of "Battlestar Galactica," and yours truly. As the first effort in what apparently will be an ongoing series, the symposium had some organizational rough-spots and awkwardness in presentation, but most participants felt the event was worth their time and enjoyed the lively repartee with the panelists.

As expected, some pretty "far out" ideas were in the scenario for home entertainment in the year 2000, with the consensus being that the home will have a central "media room," where at the punch-up of a program in a personal computer you command an incredible diversity of audio-visual sources, all presented in wall-sized three-dimensional holographs and 360-degree "live" sound. It was sort of ironic that this vision of the "brave new world" was being proposed in the midst of a gasoline crisis, since the energy requirements for this kind of installation and, indeed, many of the materials of the media complex itself are dependent on petroleum. It is obvious that, 21 years from now, we had better be operating on fusion power and have developed alternative materials for our "media rooms" or they will forever remain a fantasy. Martin Polon is to be commended for initiating this important new symposium and given a vote of appreciation as well for a smooth running AES convention.

As for the 63rd AES Convention, digital recording was as expected a prime topic, but rather surprisingly, not as dominant as in the past several conventions. Now I'm not saying that there is any diminution of interest in digital, merely that some of the manufacturers involved with digital equipment encountered problems which have delayed the debut of certain new digital products. For example, 3M's elaborate Inter-Technology Exchange (ITX, Ltd.) digital editing system evidently ran into a few "glitches," and it was deemed "not quite ready" for demonstration and subsequent production. Similarly, the long-anticipated debut of the Ampex digital recorder has been delayed. I believe they were quite close to its introduction, and, in view of this, perhaps we will see a special presentation of the recorder rather than endure the long wait until the November AES Convention at the Waldorf. However, counter to these unfortunate "no-shows" was the introduction of a new digital recorder from Technics; and an electronic editing console from Sony for its PCM-1600 digital recorder, an upgraded version of their original PCM-1 unit, now called the PCM-100, and a unique sampling rate converter, Model DSX-87.

The Technics open-reel digital recorder uses a dosed-loop tape transport based on their by-now-familiar RS-1500. This system is a radical departure from anything previously shown by Technics and features an entirely new digital code format. Tape width is one-quarter inch, and tape speed is 15 ips. It is claimed that this will permit one hour continuous recording on a 10 1/4-in. reel. This recorder (as yet un designated as to model number) uses 16-bit linear quantization with a sampling rate of 50.4 kHz. The unit uses the unique thin-film magnetic head for recording and a magneto-resistive thin-film head for playback. These thin-film heads are made by photo etching techniques similar to that employed in the manufacture of semiconductor devices. Because of this, uniformity of the heads is extremely high and costs comparatively low. This Technics recorder has four audio channels, but future formats would be 32 channels on one-inch tape and 48 channels on two-inch tape. Actually, there are 20 tracks on this quarter-inch tape ... four audio channels, and four tracks to record each channel (three data and one parity), and four auxiliary tracks for such things as SMPTE time codes and analog tracks which would permit cut-and-splice editing techniques. This machine uses the data block system, and one data block of each track consists of one word of sync, 14 words of data, and one word of CRCC (cyclic redundancy check code). One word consists of 16 bits for data and CRCC and 12 bits for sync.

All this adds up to complete parallel processing for bit-error detection and dropout countermeasures. Dynamic range of this digital recorder is rated at better than 90 dB, with THD less than 0.05 percent, and a frequency response of 20 Hz to 20 kHz plus or minus a mere half of a dB. With the SMPTE time code that is recorded on one of the auxiliary channels, electronic editing and assembly is possible, although at present no editing system is available. A great deal of interest was shown in this Technics digital recorder, especially when it was announced that the price of the unit is expected to be about $20,000, making it the least expensive 16-bit, fixed-head recorder thus far available. There, in fact, is the rub ... production of this recorder is not slated until the fall of 1980. The new Sony DEC-1000 editing controller is a very sophisticated electronic editing and assembly unit for use with their PCM-1600 digital audio processor and U-Matic VCR. This is a really slick unit, which actually permits edit points to be selected with a manual search dial and rotating the reels back and forth in the manner of present analog recorders. An auto search system is also provided. As with all present electronic editing systems, two VCR transports are necessary for editing lay-out and recording. In use, an approximate edit point within a six second range is selected and stored in a memory. Then this six-second segment is scanned and searched for the exact edit point. Edits can be previewed, shifted in two millisecond steps over a 100-mS interval. Butt and cross-fade edits are available, and edits are claimed to be accurate within 90.8 microseconds (equivalent to four 16 bit data words on the PCM-1600). Even level differences can be cross-faded over seven selectable fade times from 0.5 microsecond to 100 mS. Various LED indicators are used for editing functions, and an SMPTE time code generator and reader are available. Digital tape counters for the lay-out UMatic VCR units are provided. This DEC-1000 electronic editing system is contained in a convenient desk-type console. No pricing information as yet.

Sony was also showing its interesting two-channel DSX-87 sampling rate converter. With its own internal clock, this unit can convert in real time the 44.056-kHz sampling rates common in video-type PCM units to the 50.4-kHz sampling rates used for fixed-head digital recorders, like the Sony 3224 24 channel model, and vice versa. With inputs for external clock systems, sampling rate changes up to 55 kHz can be accommodated. The big point with this converter is that sampling rate change can be accomplished without leaving the digital domain. Conversion errors are claimed to be held to one LSB (least significant bit) for input frequencies from d.c. to 20 kHz. Last, but not the least of the new digital products from Sony is their PCM-100, which is the successor to the original PCM-1 system. The PCM-100 is a two channel unit which is the first to use the new Japanese standard 14-bit linear quantization system, although the sampling rate is still at 44.056 kHz.

Sony claims much improved error detection and dropout correction in the PCM-100, using their Cyclic Redundancy Check Code, interleaving and interpolation up to 64 horizontal lines.

With the PCM-100 and two VCR units, direct digital-to-digital dubbing can be performed with no signal degradation.

Dynamic range of the PCM-100 is claimed to be better than 85 dB, with THD of less than 0.03 percent and a frequency response of less than plus or minus a half a dB from d.c. to 20 kHz.

Here again no price information on this unit, but considering the ravages of inflation, it is unlikely to be less than the $4,000 tab for the PCM-1.

At the JVC demo room, they too had an updated PCM unit, this one using 14-bit linear encoding. It is claimed that the new PCM processor can handle either Beta or their own VHS format. JVC played a flamenco PCM recording through their new Super A amplifiers and some prototype Zero-9 speaker units which have new Dynaflat ribbon tweeters with a claimed response to 50 kHz and high power handling capabilities. The sound was exceptionally clean with fine imaging, and the high energy transients of the flamenco foot-stomping were very sharp, with impressive impact.

Dr. Tom Stockham's Soundstream digital recording service is kept very busy these days (as reported in my last column), and he was demonstrating a wide variety of recordings through the new Infinity Reference 4.5 speakers, bi-amplified with the Infinity solid-state/tube hybrid amplifiers. While the analog LP record, which is the end product of the Soundstream digital mastering system, produces some impressive sounds, there simply is no contest when you hear the sound of the digital master itself through such a high-quality system. There is no question in my mind that digital recording will only make its full impact on the audiophile market felt when it is available in true digital format, either in prerecorded digital video-cassette tapes or on laser, VISC or capacitance type digital discs.

While Ampex didn't turn up with their digital recorder, they did have an interesting new product based on digital technology. This was the ADD-1 Audio Digital Delay for disc mastering preview. Ampex was promoting this unit as part of what they termed "The Ampex Mastering System," which consists of an Ampex ATR-100 recorder equipped with their new two-channel head for half-inch tape, Ampex Grand Master tape that is, and the ADD-1 digital preview unit. I've had one of these new heads for some months now, and the increase in signal-to-noise ratio and higher head room makes a significant improvement in stereo recording. For the engineer, who is doing "purist" type simple mike setups for classical recording, this two-channel, half-inch approach is the way to go! As I am sure you know, when cutting a record, the dynamics of the recording are "previewed" by a magnetic head spaced a certain distance before the program playback head, with the time span dependent on the requirements of a particular model of the cutting lathe. The preview signal is fed into the computer system of the lathe, and from this signal the pitch and depth of the grooves is automatically controlled, before the program signal reaches the cutting amplifier. Typical delay is 1 to 1.3 seconds, with the information from the preview head continuously updating the computer. With the Ampex ADD 1, the preview head is eliminated, and instead, digital delay feeds the dynamic information to the lathe computer before the arrival of the program signal. The ADD-1 offers preset pushbutton selection of delay times up to 5.12 seconds and variable delays in 5-mS increments up to the 5.12 maximum.

The ADD-1 is a 16-bit system with sampling rate up to 50 kHz for a full 20-kHz bandwidth. An optional 100 kHz sampling rate is available for ultra wide-band recording, with a maximum delay of 2.56 seconds at this rate. The unit allows up to 30-ips mastering speed, can be used for half-speed mastering, and, of course, since there is no preview head, the wow-and-flutter performance of the tape playback machine is not degraded. The system has a dynamic range of 90 dB, which obviously will handle digital inputs. A most fascinating feature is that it can be used (on the actual recording session, of course) to preview direct-disc recordings and presumably permit more time to be recorded on a side. Ampex claims that with the combination of the ATR-100 and the two channel, half-inch head, plus the Grand Master tape and the ADD-1 delay, an 80-dB signal-to-noise ratio can be delivered to the cutting amplifier. The Ampex ADD-1 digital delay unit with 1.3 seconds of delay costs $14,500, with additional increments of delay available in optional modules at extra cost.

Before we leave the digital arena, I should mention that at the convention, news came of the digital recorder developed by the Central Research Laboratory of EMI in England. Unlike the helical-scan system of Decca, they apparently use a fixed-head open-reel unit at a speed of 30 ips in yet another new digital format. No information as to sampling rate, but one presumes it will in the 50-kHz area in a 16-bit system. Reportedly, EMI released a 12-in. single of a jazz/fusion band ..." Morrissey/Mullen" cut from their digital master. They are also said to be continuing developmental work on their editing system.

That is just about the extent of digital news from the 63rd AES Convention. Meanwhile, back at the analog ranch ... there was the usual proliferation of new audio gear, and I will report on some of these items next month, as well as bring you a review on the Calrec "sound field" microphone and ambiphonic "surround sound," which was finally demonstrated in this country and deserves special mention.

(Source: Audio magazine, Aug. 1979; Bert Whyte)

Also see: Behind The Scenes (Sept. 1979)

= = = =

Prev. | Next

Top of Page    Home

Updated: Sunday, 2018-04-22 6:35 PST