At the Winter CES there was a considerable amount of comment that many manufacturers
were not showing anything really new and were per haps holding back on their
new models and innovative products until the Summer CES in June. While there
undoubtedly was some justification for these attitudes, an excursion through
the audio exhibits at the Convention Center, and a thorough tour of the Jockey
Club (head quarters for the high-end manufacturers), enabled one to ferret
out a number of interesting new audiophile products. So here with the concluding
section of the WCES report.
If "hope springs eternal in the human breast," nowhere is this better exemplified than with the manufacturers of exotic audio electronics who exhibit at the Jockey Club at the WCES, or at the Pick Congress Hotel at the SCES.
These brave folks always seem to be willing to confront the electronic establishment with new and better mousetraps in the form of new preamplifiers, amplifiers, etc. Many fall by the wayside after a brief moment of glory in the pages of the audiophile press, usually victims of undercapitalization, bad management, or both. But there is no denying that if the products are really worthwhile and the financial and marketing pitfalls can be avoided, a star can be born.
One of the most musical sounds heard at the Jockey Club was produced by the system demonstrated by Spectral Audio Associates of Sunny vale, California. Intended ultimately as a complete integrated system, their System One consists of a pair of Quad electrostatic speakers driven by the Spectral CPU-One digital control hybrid FET amplifier. This unit uses FET hybrids and operates in Class A at 75 watts per channel/FTC. Slew rate is claimed to be in excess of a rather in credible 1,000 V/ NS, with a power bandwidth extending from d.c. to 10 MHz! A microprocessor constantly monitors all operating parameters and instantly disconnects the load if any anomalies are encountered. Above 7 kHz, a pair of Spectral MS7 direct-drive ribbon tweeters is employed and extends frequency response beyond 30 kHz. The tweeters are powered by their own Class-A 30 watt/channel, MOS-FET amplifier. From 80 Hz down, a pair of proprietary distributed bass subwoofers, each powered by its integral Class-AB 200 watt/channel amplifier, is used. This tri-amplified set-up is controlled by the Spectral MS-One preamp, which is actually the only unit now in production; the other products will be coming on stream by the fall of this year.
The MS-One is a slimline unit of modular construction. A dual mono preamp design, it shares only a specially shielded volume control; all ground circuits and shields are completely separate. Each amplifying stage is isolated with its own power regulator, and there are a total of 12 individual regulation circuits. All p.c. boards are said to be of aerospace quality, with all switchware gold over silver contacts. The MS-One has an extremely large bandwidth (3 Hz to 3 MHz); is very fast (slew rate 250 V/uS), produces minimum feedback, and has very high gain circuits to allow the use of moving-coil phono cartridges without step-up devices.
The price of the Spectral MS-One preamplifier is $1,595.00. The companion MS-100 a.c. sequencer automates the a.c. control of system components. For use with multi-amplifier systems, it has eight a.c. outlets and em ploys two separate a.c. delay circuits to turn on system components in a controlled sequence. Delay status is monitored by advancement of front panel LEDs, and this $400 unit indicates incorrect line voltage and also includes filters to minimize power surges and r.f. interference.
Obviously, the Spectral firm has em barked on an ambitious program.
Their System One offered exceptionally wide-range, clean, smooth and well-detailed reproduction, with good depth and excellent stereo imaging.
The use of tri-amplification permitted a much higher SPL output than would normally be associated with the type of speaker components involved.
Switching On To Switching Amps
Sony had a very large and impressive display of new receivers, cassette decks, and other components, but the focal point for audiophiles was their TA-N888 pulse-width modulation stereo amplifier. This is Sony's successful embodiment of the Class-D switching amplifier, which a number of companies have tried to produce. In a Class-D amp, the transistors act as switches and are either fully on (zero resistance) or fully off (infinite resistance).
The conversion of varying amplitude input signals to constant-amplitude pulse widths requires the audio signals to be sampled by an ultra-high frequency, in this case 500 kHz. Complex circuitry ultimately produces 500-kHz pulses such that at each sampled instant, the width of the pulses are directly proportional to the amplitude of the audio signals. The varying width pulses are amplified, and then a passive low-pass filter demodulates the pulse-width output back into the original audio signals. Sony found that conventional transistors did not function well at the 500-kHz frequency needed for pulse-width modulation amplification, so they utilized their special Vertical Field Effect Transistors (V-FETs) for the purpose. The Sony V FET has a high slew rate, very fast rise and fall time, and is considered quite stable and reliable. In contrast to typical Class AB or B amplifiers, with aver age efficiencies on the order of 30 per cent, this Sony Class-D amp has an efficiency approaching better than 90 percent. In a relatively small (18 7/8 in. W x 3 1/8 in. H x 14 1/8 in. D) package that weighs 24 pounds and without massive heat sinks or cooling fans, there is 160 watts/channel FTC with less than 0.5 percent THD. One of the big ad vantages of this design, according to Sony, is its soft clipping characteristics when pushed beyond its rated power output. In fact, the company claims the N88B can be pushed up to 250 watts/channel without significant in crease in distortion. This is in marked contrast to the rapid and steep in crease in THD of conventional transistor amplifiers, which exhibit hard clipping when driven beyond their rated output.
Some years ago when Infinity was working on Class-D switching amplifier design, one of the guiding lights on the project was John Ulrich. One of the founders of Infinity, he now has formed his own company, Spectron Electronics, Inc. in Chatsworth, California. Evidently John decided that further research into switching amplifier design was worthwhile, and now here he was at the Jockey Club proudly displaying a Class-D switching amplifier. In the Spectron configuration, two 250-watt mono amps are mounted on a single 3 1/8 inch thick rack-mountable package weighing 18 pounds.
Power supply is a pulse-width regulated switching type operating on either 115 or 220 V at either 50 or 60 Hz. The unit is furnished with an LED bar graph to display output levels. At 18 pounds there obviously are no large heat sinks involved, but a small fan is provided for horizontal cooling so the amplifiers may be stacked in rack mounting. Price of the Spectron Class D amplifier is expected to be around $1,500.
Towers of Power
For some time now, a company named VMPS Audio Products has been advertising in the classified advertising section of Audio. They manufacture columnar-type loudspeakers, utilizing multiple driver units and making some fairly outrageous claims for performance, and all at quite modest prices. Lo and behold, in my journeys through the corridors of the Jockey Club, I found a demonstration room for this company, which turns out to be a division of Itone Audio of El Cerrito, California. I must confess that I was preconditioned to this type of loudspeaker, having heard many examples, mostly of foreign manufacture. For the most part, they were sonic abominations, usually characterized by incredibly boomy exaggerated bass, midrange peakiness, shrill and searing high frequencies, no depth, no imaging, and every sonic coloration you can imagine. When I walked into the room, my heart sank because there was this huge black column standing 83 inches high, covered with assorted sized speakers from top to bottom.
Determined to hear this "thing," I gritted my teeth, activated my auditory protective filters, and asked the young fellow in charge for a demonstration.
Well!!! It is rare that anything in audio surprises me after all these years, but I was literally flabbergasted by hearing some of the best sound at the Show! Partly my shock was the totally unexpected reaction to hearing such excel lent sound from what previous experiences had led me to expect would be the worst. It didn't take long to find out that the enthusiastic young man in the room was company president and designer of the speakers, Brian Cheney. He is a veteran audiophile and a devotee of the minimum phase-response theories of Audio's Dick Heyser. VMPS Audio manufactures four speaker systems, the Mini-Tower 2, Tower-2, Super Tower, and Super Tower-2, the system to which I had been listening. All are of the minimum phase-response configuration and are sold either fully assembled or in kit form at considerable savings.
Because of space limitations, I'll concentrate on the top of the line, the Super Tower-2. There are a total of 16 drivers in each of these speakers. One 15-inch driver is bottom-firing and slot loaded; another 15-inch driver is front-firing. This is the subwoofer section.
Then come two 12-inch low-bass drivers with staggered resonances and compliances. Next is a 12-inch mid-bass coupler. Midrange is handled by four 5-inch butyl surround drivers with staggered resonances. Five 1-inch soft dome tweeters are in a vertical line source array, and two piezo-horn super-tweeters are at the top of the line source. The speakers are sold in mirror image pairs, and either full range or bi amp operation is possible without external crossover. Bi-amping is recommended for the Super Tower-2, and Brian Cheney was demonstrating them in this mode using Bedini Class A, 100 watt/channel and 25 watt/channel amplifiers.
Doesn't sound like much power? Well, the efficiency of the Super Tower-2 is 103 dB at one watt/one meter. If you would like to feed in the maxi mum 500 watts, you will get a chest-squeezing 132-dB output! If you want bass, the-3 dB point of low-frequency cut-off is 17 Hz. Cheney is very proud of the fact that he can quote distortion figures for the Super Tower-2 at less than 0.25 percent THD, 22 Hz to 30 kHz, with one-watt input. He played a variety of music, all of which was very smooth and clean, highly detailed with tight, rock-solid bass fundamentals, minimal coloration, and in spite of the multiple drivers, no sense of disparate sound sources. Imaging, in fact, was quite good. Then Brian played the Telarc 1812 Overture, and not only were the cannon reproduced with gut-thumping power, but you heard the real low-frequency fundamental with no doubling.
I am certain that this speaker is one of the few that will have no difficulties handling the dynamic range of true digital recordings when they finally arrive on the audio scene. You can buy the kit version of the Super Tower-2 for $799. The cabinet is fully assembled, and Brian states that about five hours of work installing the drivers is about average. For those who don't dig kits, the speaker costs $1,299 in black and $1,499 in rosewood. Prices quoted are for each speaker. Warning:
The Super Tower-2 is a BIG speaker and shipping weight is 300 pounds.
The moral of this tale is obvious-even if the speaker looks a bit weird, take time to have a listen.
Cartridge and Arm Wrestling
There are those who will tell you that the analog disc and the phono-graph cartridge and arm are in the twilight of their long history, that there is little technological progress that can be made or is worth bothering about before this music reproduction system sinks into oblivion. It has been said many times before. But when stereo tape threatened their existence, we learned how to put two channels of sound in the grooves. The quadraphonic sound era started with tape, but even with that, we figured out how to put four channels of sound in the groove. This time, maybe digital audio will indeed knock the tough old analog disc out of the ring. Perhaps it is inevitable, but there are some pretty sharp marketing people who think the ultimate demise is still a long way off and that further refinements can be made in the existing technology.
For all his genial exterior, Dave Fletcher of Sumiko, importer of the Supex moving-coil cartridges and other assorted phono gear, is a very savvy and canny guy. He's figuring that his segment of the high-end phono market is still very much interested in up grading the quality of its phono reproduction, hence his marketing hand- made Koetsu moving-coil cartridges, at $1,000 each. Similarly, he is introducing what will be known as The Arm, a high-technology design using super-precision bearings expected to sell for a cool $1,100! You don't think audiophiles will pay these prices? With inflation whittling the dollar's value down to 48ยข, it's possible.
In the same rarefied area, Dynavector has recently introduced what they call their DV-Karat and DV-Karat Diamond moving-coil cartridges. There is much new technology here, including the fact that the cantilever on the DV-Karat is made from solid synthetic ruby, while the DV-Karat Diamond, rather incredibly, has a solid diamond cantilever. Moreover, the cantilevers are very short, only 2.5 mm rather than the usual 6 or 7 mm. I had the pleasure of meeting Dr. Tominari, President of Dynavector and inventor of these cartridges. He was Prof. of Mechanical Engineering at Tokyo University, speaks fluent English, and we had some interesting discussions about these radical cartridges. In order to mount the diamond stylus in the cantilever, a special new type of laser "drilled" the very tiny hole. The cantilevers themselves are specially ground and polished from blocks of ruby, sapphire, or diamond. The coils are very tiny and wound with silver wire, samarium cobalt rare-earth type. Unlike most moving-coil cartridges, these have relatively high compliance and are meant to be used in low-mass arms. Tracking force is also low, 1.5 grams optimum. Dr. Tominari pointed out that because the cantilever is so short and Karat Diamond is composed of the hardest material known, wave propagation is very fast.
I have been using the diamond cantilever cartridge recently, mounted in the Technics EPA-500 arm. The total weight of the Diamond Karat is but 5.3 grams and, mounted in this Technics arm tube specifically designed for the compliance range up to 15 x 10^-6 cm/ dyn (which just happens to correspond with the cartridge compliance),, arm/cartridge resonance interaction is minimal. As you might expect, tracking is superb. The sound is exemplary in every aspect and is the best I have heard from a moving-coil cartridge.
The greatest point of superiority, most probably due to the short diamond cantilever and the fast wave propagation pointed out by Dr. Tominari, is the blazing fast transient response.
Playing a direct-to-disc recording like the M & K release of Ed Graham's Hot Stix is a revelation. With cartridges like this and other ongoing developments, there is bound to be life in the old discs yet!
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(Source: Audio magazine, May 1980; Bert Whyte)
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