Phil Leigh;175800 Wrote: > But...adding a 1kHz tone to (the analogue representation of) the digital > signal wont create analogue noise in the DAC - it just makes it harder > for the DAC to recover the bits... >
Well, not really. Adding noise to the digital signal (and yes PF, by digital signal I obviously mean the electrical S/PDIF signal transmitted along the wire, not the abstract sequence of bits) will change the analogue output of the DAC. This is called jitter; it results from the fact that (most) DACs use the transitions in the digital signal as a clock. If there is noise it affects the derived time of arrival of those transtions, resulting in a jittery clock, which in turn results in a distorted output waveform. The difference between that distorted waveform and the ideal is nothing but a form of noise at the analogue output - and in fact that's exactly what Stereophile measures in their tests and refers to as jitter (but it's NOT what Sean measured - he made a direct measurement of timing variations in the digital signal). > > The effect of EMI on digital and analogue circuits is completely > different AFAIK, In this case it is different - see my post above - but not completely so. My point stands - it stretches credulity to the breaking point to think that some jitter-induced noise overlaid on much louder music is more audible than similar noise amplified maximally and played against silence. -- 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
