| Actually most modern personal computers intentionally insert jitter into the master clock of the computer in order to limit the RF emissions from the computer, and thereby pass FCC testing. This is desirable if you want to sell any computers. Digital audio systems however are different because they use both the data and the timing of the clock to reproduce the original recording. The data stream is transferred "real-time." |
| There are a number of key components in typical digital audio systems where contributions to jitter is significant, including: 1. The pits in the CD 2. Reading of the pits by the optical read-head of the transport 3. Jitter in the master clock in the transport and Jitter in the asynchronous re-clocking in an upsampling DAC 4. Transmission of the S/PDIF signal 5. Dispersion of the signal in the S/PDIF or AES/EBU cable 6. The electrical-optical-electrical conversions in a Toslink interface 7. Conversion of S/PDIF to extract clock and data 8. Noisy power supplies and ground-loop noise |
| Computer-driven audio usually eliminates jitter contributors 1, 2 and 3. In some cases it also eliminates or minimizes jitter contributors 4, 5, 6, 7, and even 8. |
| Originally Posted by markl From one of the articles linked: This author is discussing the positive attributes of digital music servers, not PCs, which do appear to have some limitations jitter-wise. |
| Originally Posted by Iron_Dreamer This is not applicable, because the "master clock" of the PC is not what is used to generate the audio signal. EVERY soundcard I've ever seen, including the $10 jobs had their own clocking mechanisms onboard, and on SOME soundcards they use the same sort of high-quality clocks used in CDP's and DAC's. |
| Originally Posted by markl From one of the articles linked: This author is discussing the positive attributes of digital music servers, not PCs, which do appear to have some limitations jitter-wise. Further, he goes on to list causes of jitter: If you are using a computer as a transport for a separate outboard DAC, looks like, according to this author at least, you still have 4-8 to worry about jitter-wise, even if effects may be less than using a CDP as a transport to an outboard DAC: So, computer or music-server-based audio is not "perfect" either, though it has its advantages as a transport. But if you are using a high-quality (good PSU) all-in-one CD player without an outboard DAC, it seems to me, issues 1-3 are still a factor, but 4-8 don't apply as you are not outputting a digital signal to an outboard DAC. 6 of 1, half-dozen of the other. |
