seanadams;194661 Wrote: > > The notion that s/pdif moves so glacially as to be unaffected by > reflections is just nonsense. What you are saying is equivalent to > claiming that wire has no resistance because a lamp glows just as > brightly with one foot of wire as with a hundred. Just because you > don't have an ohm meter, or you can't perceive the difference in > brightness, doesn't mean it is not there! With suitable equipment (like > what telecom engineers use, not hifi magazines) we can easily measure > jitter and we can see how an s/pdif signal is affected by these things. > It is just silly to speculate about these quantities when they are so > easily measured. We can see how slower rise times yield more jitter, or > how an impedance mismatch affects the waveform. And with a high > frequency test tone played through a DAC we can see how levels of > jitter as small as ~50ps can be observed in the output of the DAC. How > much of this is audible is up for debate, but it's all real and > observable.
Sorry - I typed that early in the morning and mixed pico with nano, as several have pointed out. It's not at all equivalent to a lamp with a long wire... What I said was not that there are no reflections, just that the S/PDIF frequencies are far below the transmission frequency and therefore reflections and impedance matching should be far less important than they are for transmission lines. There may still be a effect, but it should be quite small - and ps or even ns of jitter is a tiny effect in a 5 MHz signal. In any case, I really don't understand why it's so difficult to deal with these levels of jitter (which shouldn't come anywhere near to causing bit errors). It's trivial to design a DAC that is completely immune to input jitter - just record the bits in a buffer for however long you need to in order to deal with slight differences in average clock rates, and then play them out later, using a local clock. That might not be a convenient solution all the time, but it's a clear proof-of-principle. Why is it so hard to implement practically? -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=34406 _______________________________________________ audiophiles mailing list [EMAIL PROTECTED] http://lists.slimdevices.com/lists/listinfo/audiophiles
