Stop Digital Madness! JGH Responds
Anyone who extracts from a manufacturer, as a condition for returning a preamp for repair, a promise that no digitized music be played in the room with it, and then denies being antidigital, is trying to kid somebody.
Despite the prolixity of Prof. Reilly's response to my editorial, she has still made no attempt to address the questions I see as crucial to this whole affair. These questions are:
1. Who were the "others" whose "independent tests confirmed" that ultrasonic information accompanies digitized music? Names and publication attributions, please.
2. At what frequency, or between what range of frequencies, are these "spuriae" supposedly observed?
3. Who were the "we" who found microcracks in spindles of turntables that had played digitally-mastered discs, and not in ones that had not? How was access gained to the electron microscope necessary to observe the microcracks? Names of people, location of microscope, please.
4. Who were the "experts," in which "two large companies," regularly working in which "fields," who found these microcracks? Four names, please.
5. What were the test results for analog-mastered discs, but which had been digitally-remastered or were cut using a digital delay for groove pitch and depth control? How were such discs identified, if at all?
6. Since digital audio's sampling pulses are absent after D/A conversion, what does Prof. Reilly hypothesize as the source of those "ultrasonic spuriae" from digitally-mastered discs? Any reasonable guess will suffice here.
7. What is the nature of the transmission path by which "ultrasonic spuriae" reach a platter spindle? A reasonable-looking guess will suffice here, too, pending subsequent confirmation.
8. Since the books Prof. Reilly cited as referencing microcracks due to ultrasonic energy are not readily available here in Santa Fe, I must ask the good Professor what energy levels they mention as being capable of causing structural damage? Quantities, in watts, please.
9. According to those references, below what intensity, in watts, will ultrasonic energy not produce microcracks in hardened steel? Or is it posited that any measurable quantity of ultrasound will cause damage over time? Here we need a quantity, a yes or no, or an admission of ignorance.
10. The term "smear" is generally used to describe speed variation occurring too rapidly to be heard as flutter—at a rate of about 50Hz or more. Such variations are, however, definitely not "outside the range of conventional audio measurements." Why not use a spectrum analyzer to display a test tone and its sidebands? This approach is a valid way of measuring frequency deviations at modulation rates up into the gigahertz range. Give one good reason why it couldn't be used here?
Finally: While Neil Levenson is a likable chap and a respected audio reporter, he has never laid claim to a strong technical background. His failure, in his Fanfare report on Prof. Reilly's activities, to raise the questions I have just raised again in this magazine, may have "compromised" his reputation more than anything I said about him.—J. Gordon Holt