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In Reply to: RE: Ayre C-5xeMP break-in suggestions wanted posted by cawson@onetel.com on May 12, 2009 at 11:05:37
"I do accept that a single box CDP is (or at least should be) superior to the 2 box solution, but you must admit that 10 years ago, many of the top CD players were in fact 2 box ones. More (maybe too much) emphasis now seems to be attached to the problem of jitter than 10 years ago."
Some time ago, the jitter issue wasn't as well understood as it is today. And back in those days, DAC chips had serious problems of linearity, noise and distortion. So people worried about more pressing issues than jitter. I owned one of those two box players, a Proceed, and it suffered from jitter problems. In particular the TOSLINK sounded noticeably worse than the SPDIF. Of course the player was a huge improvement over the Sony CDP-1 that it replaced. :-)
If the clock controlling the DAC chip is to derive its timing from an external source, as it must if it is being slaved to a transport connected via standard SPDIF, then that clock needs to have variable frequency capability. Such oscillators have much more phase noise than the simpler and more stable crystal oscillators used in stand-alone clocks. Unless a player uses two separate clocks, one for internal use and the other for external use, its internal jitter performance will be compromised. Supporting extra clocks and switching between them adds complexity to critical circuitry, so this will be costly if performance isn't to be compromised.
Clocks, digital output buffers, the actual DAC switches, as well as all the power supplies they use are analog components in the signal path— their analog characteristics affects sound quality as much as opamps, class A analog output stages, or any other analog audio electronics.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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