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Music servers and other computer based digital audio technologies.

RE: Improved Regen sound

I don't doubt the perceptions, but the theory seems somewhat incomplete. The problem is that the clock is the USB bit clock. Phase noise has nothing to do with phase noise modulating the audio clock, because this clock is at a totally unrelated frequency. A possible theory might add that the regulator noise caused jitter in the USB bit clock affects the USB receiver circuitry's power consumption. This is related to John S's theory of how the REGEN works to improve sound quality, but as far as I know this is just speculation as there is no hard evidence of what is going on.

We do know that noise on the REGEN power can be coupled into the analog output of some DACs in the form of common mode noise. This noise appears at the packet clock rate (8 kHz), indicating that the regulation isn't sufficiently stiff.

It beats me why DAC designers don't deal with these issues. There is no excuse for any 8 kHz noise to appear in the output of any USB DAC, regardless of the input signal, assuming only that the input signal conforms to the USB specification.



Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar


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