Frank Van Alstine, modifier of Dynaco amplifiers and producer of the new Van Alstine Model One preamplifier, was the first speaker of the evening. He began by citing some key points of his audio "philosophy" and how they relate to the evaluating and modifying of electronic components. The first point he raised centered on the question: Are you sure your evaluations of audio products correctly describe what is actually taking place? Product evaluators of both the mass-market and esoteric audio magazines can be deceived by perceived changes in the sound of a system containing a new component. For example, a reviewer might take a system with which he is intimately familiar and substitute a new preamp for his old one in order to "test" it. Any differences he then hears, Van Alstine argued, will be attributed to the newly introduced preamp. The problem with this is that the new preamp may be so much better than the previous one that it reveals troubles elsewhere in the system. If the system with the new preamp sounds "brighter" and "grainy," it may be the case that one is hearing problems with the arm bearings or cartridge which the other preamp obscured. In this way, he argued, reviewers often end up evaluating the wrong component in a system. He also suggested that sonic differences between phono cartridges, especially those between samples of the same cartridge, are probably more often caused by differences in the adjustment of the tone arms (e.g., vertical tracking angle, overhang, etc.) used to evaluate the cartridges than to the cartridges themselves. Van Alstine claimed that one can easily hear differences as small as two minutes of arc in vertical tracking angle, differences which could be mistakenly attributed to the cartridge involved.
He next offered a statement of what he regards as the purpose of an audio system: "to recreate the illusion of live music in your room in three dimensions." The more accurately "the out-put follows the input the better the system is going to sound." On this latter point he criticized Bose (though not by name) for building speaker systems that do not attempt to accurately reproduce the sonic equivalent of their input but instead add the "distortion" of artificial concert-hall reflections to the sound.
As to the proper way to evaluate audio components, Van Alstine remarked that he regards listening tests as the "objective" test of a component because the "object" of the component is to play music. Electronic measurements he argued, are "subjective" because they don't, at this time, correlate well with the sound reproduced.
The Van Alstine modifications of Dynaco components are expressions of this philosophy,
he maintained. Dynaco products are well designed components which employed parts which often interfere with the function of the unit intended by the
designer. Therefore, he said, he substitutes higher quality electronic parts for the originals to enable the units to behave as the designer
intended. Among such changes he cited were the substitution of 1% metal film resistors for 5% car-bon composition types, silver mica replacements for
Mylar capacitors, and the replacement of transistors with selected low noise units.
Finally, Van Alstine offered the members some tips on how they might improve their own audio systems. Specifically, he suggested that one can damp the high frequency resonances intone arms by pressing a small (1/4 inch diameter), 1/2 gram glob of modeling clay (the kind that does not harden) onto the rear underside of the headshell, just behind the cartridge. Also, he suggested, the hard dome in the center of many dynamic speakers can produce audible ringing, and that a disc of clay (1/2 inch for a midrange, 1 inch for a woofer) pressed onto the dome could eliminate this effect. For soft dome tweeters, he (rather tentatively) suggested poking a hole the size of a pencil lead into the dome. (Representatives of Allison Acoustics and Acoustic Researching the audience suggested yet another effect of poking holes in tweeters -- cancellation of warranties.) Van Alstine admitted that one could not tell in advance if this treatment would help his speakers and cited no satisfactory way to fill the hole in the tweeter dome if the treatment did not work.
A demonstration of the tone arm damping using modeling clay was then attempted with the following components: a Phillips turntable, ADC XLM cartridge, Van Alstine Model One preamp, Van Alstine modified Dynaco 400, and Cizek Model One speakers. After playing sections of the EMI pressing of Holst's Planets (Previn/LSO) both with and without the clay connected to the head-shell, Van Alstine polled members as to whether or not they heard a difference (about half did) and whether the clay improved the sound (no clear consensus on this). Because of time pressures, great care could not be taken in this A/B test, and significant factors (e.g., tracking force) were only approximately equal. Recognizing this, Van Alstine suggested that each member of the audience try it on his own system and see if it works.
The ensuing question and answer session was lively and often heated, with Van Alstine
being challenged on several of his assertions. Two of the most controversial points seemed to be
his cavalier attitude toward electronic specifications (on the ad sheet for his preamp he cites as
a damping factor "unit should not get wet") and his claim that substituting higher quality parts in
a well designed amplifier would a priori result in a better sounding component. On the former,
Van Alstine said that he really didn't know the precise frequency response of his preamp but that
it was essentially flat to within one dB "over several megahertz." He argued that this was of
little importance anyway since, in his view, "raw differences in frequency response" were not a
major factor in the differences between the sounds of preamps. This comment led to a heated
exchange between Mark Davis of MIT and Van Alstine, Davis reporting that in tests done by BAS
members, it was found that provided that noise was kept to a reasonable level, frequency response was
the most significant factor in determining the sonic performance of a preamp. Further, Davis
stated, once the relative frequency responses of various preamps were carefully matched, they
became sonically indistinguishable. Van Alstine doubted that this was the case.
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