seanadams;299799 Wrote: > The crystals in SB3 are specified to within 50ppm accuracy, so if you > take the worst case where one is fast by 50ppm and the other is slow by > 50ppm, then you have a total drift between the two of 100ppm or > 0.000100. After one hour, the faster player would be ahead by 0.000100 > hours == 360 milliseconds, which is easily audible. In reality I don't > think you would ever find crystals as bad as that, but it's easy to see > how even at +/- 10ppm, correction for clock drift is still required. I > would estimate the threshold of audibility for the casual listener to > be about 50ms. > > As an approximate rule of thumb 1ms is equal to 1 foot at the speed of > sound. Typically there is some distance between the two rooms so you > would add that to the drift that is perceived. > > Certainly Transporter has a better clock but it is hard to estimate > exactly by how much two Transporters might drift slower than two > squeezeboxes. It's a manufacturing tolerance issue so you can't really > characterize it without comparing LOTS of units. In any case, a design > which depends on two crystals having exactly the same frequency is > simply broken as this is never achievable in practice. Even two > perfectly identically manufactured crystals will not behave the same in > a real world setting because they will be operating at different > temperatures, and this affects the speed too. > > I am not entirely up to speed on all of the improvements that Alan has > made but my most recent understanding is that we still resync on track > boundaries. This is not an unreasonable approach, but it's not ideal > either because it inherently makes it difficult to do gapless playback > while synced. To do that we would need to implement a gradual > correction scheme where clock drift is corrected over a relatively long > period of time.
I have sync problems with SC7.0 and the suggestion in my case is that this may be due the drift of the clock of the hardware that sc7.0 is installed on, in which case the accuracy of the SB3 crystal is irrelevant to a certain extent? I have to stress that the analysis of my problem is not complete, however, the implication here is synchronisation is a function of the players only?? -- nwplace ------------------------------------------------------------------------ nwplace's Profile: http://forums.slimdevices.com/member.php?userid=16529 View this thread: http://forums.slimdevices.com/showthread.php?t=47344 _______________________________________________ discuss mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/discuss
