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And now I've seen them as well....

Went over to John's last weekend, and we took a look at some of those measurements (and measured my Purist Colossus IC)

The question of whether John's measurement rig is flawed has been beaten to death, but here's what I saw:

We exchanged 4 or 5 different kinds of cable, all RCA terminated, and each cable exhibited 2 things:

1) A different pattern of harmonics of the original signal that was perfectly repeatable; we could exchange the cables back and forth and always get the same spectrum for a given cable. Some of the spectra included significant amounts of 8th - 10th harmonics.

2) A different pattern of noise (i.e. signals at frequencies unrelated to the original) that was also repeatable. Obviously, the shielding ability of the cables is different.

The repeatability of the tests makes me believe that the harmonic spectrum is not due to connector issues on the test setup, as was suggested in an earlier post, although I suppose you could always argue that the complex comination of distortion analyzer, RCA adapters and spectrum analyzer creates the signature, rather than just the cable. Sounds like what happens in a real audio system to me...

John's test set up is actually quite straight forward, and not all that hard to duplicate, so I'm mystified by the fact that so many people have foamed at the mouth about it, but none have tried it.

It's also interesting that nobody has been able to explain the results, prefering to shoot the messenger.

Peter

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