But those numbers were obtained by a completley different methodology. As far as I understand, Sean is looking at the *digital* S/PDIF signal at the coax digital out of the SB. I'm not sure what the test signal is. The pk-pk value is then the distance between the earliest and latest clock transition, in other words the width of the jitter distribution at its base. A better (for several good statistical reasons) number to look at is the rms value. The two are consistent (to within the error) with the jitter being random Gaussian noise.
Stereophile, on the other hand, is playing a pure test tone and then looking at the *analogue* outputs of a DAC. Jitter will induce sidebands to the input tone, but this is a very complicated process involving many elements other than just the transport (like cables, DAC, etc.). Furthermore I think it won't see some types of jitter at all (for example it would miss at least some of the correlated jitter effects, like those that distort the frequency response by changing the amplitude of the primary tone but don't induce sidebands). Also I don't see how you can extract the numbers Sean measured from the analogue signal without some fairly elaborate algorithm - probably one that essentially performs an A->D on the signal, which will again introduce errors (including more jitter!) that have nothing to do with the transport. And one last point - I poked around a little and saw that there are different conventions in the literature for what peak-peak means. It's possible it's sometimes defined with a factor of two relative to Sean's definition, so that it measures the distance from the *center* to the edge of the distribution. That would mean you should divide Sean's numbers by 2 to compare (to be clear I'm not saying that's the case - I don't know - but it's a natural definition, and it's clear from the little I read that there is some confusion over conventions). So I simply don't think you can compare, at least not until Stereophile reviews the SB or Sean gets hold of a player they've already reviewed. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=25188 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
