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CD Transport to DAC Timing/Jitter

I am not clear on the source of excessive jitter that can occur between a CD transport and DAC. As I understand it the transport internal oscillator acts as the master system clock. The DAC in turn runs on recovered clock derived from the incoming transport signal. If this is true then the only thing that should cause timing jitter is long strings of consecutive zeros which would adversely affect the DAC clock recovery circuitry. I would think that this would be prevented by scrambling the data or by some zero substitution algorithm similar to what is used in the telecommunications world. Any ideas/comments on this issue?
7p62mm
dan2112
144 posts
 
If my memory serves me right one of the Stereophile Test Disks (I think it's #2) has an example of what jitter sounds like. But Redkiwi is correct. To me it sounds like the digital glare of the first CD players. Cheers, Dan
dustych
53 posts
 
Redkiwi is pretty much correct -- lost focus and soundstaging. It's pretty hard to describe, until you hear it go away. Also, the explanation I was talking about is at this address: http://www.lcaudio.com/dacdrev.htm -- this is a company that sells upgrade clock chips for CD players, but there is lots of good information on jitter on their site.
spokanais
11 posts
 
Ask your self a question. Does jittering of digital signal in time domain influence the characteristics of the analog output of your DAC? which is frequency and phase critical for the localization of sounds reproduction. The answer is yes. The stereo signals store on the CD is multiplexed into a single stream of digital signals. The error in demultiplexing the stereo in time domain (timing jitter) will introduce mismatch in phase (not to mention IM distortion) for the analog signals generate by the DAC. Most of the modern CD players are incorporated some forms of clock recovery circuit so the jittering problem I think does not exist anymore.
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