erm, guys... a perfect square wave can by definition only have 2 DC values with an instantaneous transition between them (of course this is not possible in the real world but we can get pretty close to perfect) with a (variable or fixed) mark/space ratio determining the periodicity/instant of the transition.
Jitter does not change the 2 DC values - it changes the apparent exact moment in time when the transition takes place. Even if the DC values did change slightly because of poor PSU regulation/decoupling, they'd still represent a (logical) zero or one to the recipient, unless they went wildy out of tolerance. These changes to the timing of the transitions may be random, periodic (eg related to an AC frequency elsewhere in the circuit such as the mains) or correlated to the music because of the DAC analogue stage impacting something in the clocking/clock recovery chain via the PSU rails for example. Anything in the DAC chain that can alter the analogue output AND that relies on knowing exactly when the transition is supposed to take place is thus in jeopardy from jitter. Jitter can be introduced by any transport - this can be removed - maybe completely - or at least ameliorated just before or just inside the DAC. However, lots of CD's are in fact created from jittery digital masters/multi-tracks - and this can't be removed at home!. Thankfully this problem has more or less gone nowadays... There is another corruption mechanism (not jitter) that intermittantly mangles the square wave so that it is harder to detect the transition point in the receiver - or even that a transition has occurred. The resultant bitstream has unrecoverable (but possibly interpolatable) errors - this is the damaged cellphone/sat TV/CD dropout syndrome... Robin - are you saying that you don't think jitter exists (in which case, what does a jitter meter measure?) or that it does exist, but the presence of jitter on the digital stream doesn't affect the performance of the DAC? -- Phil Leigh ------------------------------------------------------------------------ Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85 View this thread: http://forums.slimdevices.com/showthread.php?t=24670 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
