jkeny wrote: > As I said in my post "Of course I could be wrong in my interpretation of > these 8KHz spurs - more testing is required, I reckon" Not sure why you > need a response when the answer is there? > > But I'll have a go, anyway :) > > You have measured 8Khz & harmonics spurs in USB audio, ArnyK has > measured 8KHz & harmonics spurs in USB audio DACs, BE718 has measured > 8KHz spurs in his USB audio. > What you are asking me is - are Amir's 8KHZ & harmonics shown in his > measurements due to the same mechanism as these others? Unless he does a > measurement to tease this out, we won't know for sure but I can tell > where I would put money! > > Anyway, it appears that there is a ground loop condition set up by the > ground lift resistors in the Regen that is being picked up in any test > setup that isn't fastidious about avoiding ground loops & it appears > that this is why we are seeing these spurs in some measurements & not > others. It appears that the 8KHz is coming from the USB hub chip's > handling of the 125uS microframes but with better PS treatment this will > probably disappear?
Okay, thanks John. No worries, just wanted to get a read on your thoughts on this 8kHz phenomenon. True, the 8kHz tone can be measured in some circumstances with gear susceptible... Will need to see if Amir can run through another test to differentiate this from his original thought that it's sideband spikes and potential jitter rather than microframe noise. Archimago's Musings: (archimago.blogspot.com) A 'more objective' audiophile blog. ------------------------------------------------------------------------ Archimago's Profile: http://forums.slimdevices.com/member.php?userid=2207 View this thread: http://forums.slimdevices.com/showthread.php?t=104340 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/audiophiles
