P Floding;175883 Wrote: > No, because it is not "overlaid". It is correlated. You don't get > "similar noise" from your described methods. >
OK, I guess that wasn't my last post... Take the actual waveform, subtract the ideal, and that's the noise spectrum (or distortion, or choose whatever term you prefer - from now on I'll refer to it as noise). Because everything here is linear, you can think of the actual signal as the noise plus (overlaid on) the ideal signal. Some of that noise comes from jitter, and some comes from thermal noise in the analogue stage, and some comes from EMI, etc. Now, noise due to jitter is correlated with the signal in the following sense: if you add some jitter with frequency x to a signal with frequency y, you get noise concentrated at frequency y-x and y+x, as well as some other components. If you add that same interference to an analogue signal, you just get noise at x (this is what I said two posts back), so that could be said to be uncorrelated with the signal. Of course if you add full spectrum noise to the digital signal you will get full spectrum (possibly with a different shape) noise at the analogue out, so there the difference is qualitatively much less. My point, again, is that the noise due to jitter is going to be much harder to hear than the noise directly added to the analogue stage if the source of both is the same old EMI. So if you don't hear any change in the noise floor when you unplug the wallwart I'm very skeptical there can be any change when music is playing. It would be interesting to see if there's some DAC design for which this isn't true - maybe you could build a DAC which greatly amplifies jitter at certain frequencies or something... what DACs are you two using? -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=32231 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
