In Reply to: RE: PC + Asynchronous USB DAC Question posted by play-mate on December 30, 2011 at 14:30:53:
The problem with this statement is that the interface between the computer and the DAC is the same regardless of which isochronous mode you use, be it adaptive or asynchronous. The DAC still must use PLL circuits to capture the USB data since there is no clock. Asynchronous mode just provides a feedback path from the DAC to the computer to adjust the source data rate. It doesn't guarantee any better performance. That has to come about from good engineering on the DAC side in order to keep all the jitter in the interface circuit clocks out of the audio clocks (and data as well), which isn't a simple task. It is easier with asynchronous mode because one then has the option to use a high quality local clocks in the DAC (you need more than one clock to cover the various sample rates if using fixed frequency oscillators), but that isn't what everyone does.
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Follow Ups
- "When the DAC ..is asynchronous, it should not be affected by any jitter from the computer" - slider 19:26:27 12/31/11 (1)
- RE: "When the DAC ..is asynchronous, it should not be affected by any jitter from the computer" - play-mate 01:53:32 01/02/12 (0)