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RE: "J. Gordon Holt tested the ABX Switchbox and declared it was sonically invisible."

"While members of the Boston Audio Society DB-tested it and found to the vaunted 99% confidence level that its insertion was fully audible"


The only problem with that story is that it never happened.

There is something you may be remembering, incorrectly. Micha Schattner and I discovered that the ABX high-current module, used for power amp switching and equipped with high-current speaker relays (but not for line-level tests) made a soft mechanical clang that was different depending on whether A or B was being chosen. We tested the audibility of this with the relay module a few feet away from us and no signal in the system, in a very quiet room, and we could hear the difference. I don't remember the number of trials but it was 8 or 10 apiece, all correct, so there was no doubt we were hearing it.

This effect is irrelevant to ABX testing, for at least three reasons. First, you can muffle that sound easily even with no music playing -- a couple pillows over the box and you can't hear it any more. Second, with music playing you don't even have to muffle it (though I always do); it's so soft that any music masks it. And third, neither this box nor the reed relays used for line-level switching affect the audio signal at all. -- EBM


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  • RE: "J. Gordon Holt tested the ABX Switchbox and declared it was sonically invisible." - EBradMeyer 03/10/0811:24:31 03/10/08 (0)

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