SoftwireEngineer;147033 Wrote: > With due respect to Clive (and Sean) - I am not sure I agree that this > article is hogwash. It requires lot of engineering in a CD player to > isolate it from the jitter or the time variance in arrival of the bits > from the optical disk. Well now, the act of buffering the data coming from the laser mechanism and then clocking it out does indeed isolate the downstream parts from the vagaries of reading the disc (that's what a buffer does, after all), unless something in the act of reading the disc can affect the clock that's used to read the data out of the buffer. Which brings us nicely on to...
SoftwireEngineer;147033 Wrote: > BTW, One of the engineering details I remember on how the laser servo > affects jitter is thru the common power supply, more servo activity, > more power supply variations, more jitter in the master clock. I suspect you are referring to the study by Prism and DCA into the possible audible differences between numerically-identical CDs. As far as I am aware, this is the only study of its kind so far that was conducted under proper scientific conditions. For anyone interested in the gory details, the original paper is at http://www.prismsound.com/m_r_downloads/cdinvest.pdf. To briefly summarise: they found that there was a measurable effect on the analogue outputs of one-box CD players due to interference from motor & servo activity. This effect was not found in two-box players. Moreover, they did not find any impact on jitter by the motor/servo activity. All the evidence is that the motor/servo affects analogue circuitry, but *not* jitter. Of course, what the actual mechanism for any effect happens to be is not important to the listener: if the act of reading a spinning optical disc can affect the sound, then perhaps a no-moving-parts device like the SB is indeed an improvement. Unfortunately, despite the measurable differences observed, when they conducted a blind listening test, two highly respected (but unnamed) listeners failed to correctly identify which disc was which. This seems to suggest that the difference is very subtle and probably below the threshold of audibility (except when you know what's playing, in which case it is easy to hear the difference, of course :-). -- cliveb Performers -> dozens of mixers and effects -> clipped/hypercompressed mastering -> you think a few extra ps of jitter matters? ------------------------------------------------------------------------ cliveb's Profile: http://forums.slimdevices.com/member.php?userid=348 View this thread: http://forums.slimdevices.com/showthread.php?t=28621 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
