Re: ADAT Output Problems...the last of my updates

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Posted by Mark Bonnington on September 29, 2001 at 03:07:50:

In Reply to: Re: ADAT Output...More New Information...this is getting ridiculous posted by Mark Bonnington on September 29, 2001 at 02:39:20:

The last clarification, and a possible solution: The clicks and pops are a nearly steady stream on three or four programs (mostly organs), while the clicks and pops occur infrequently for most other programs. My QS8.1 clock was set to 48kHz when the pops and clicks occured. The clicks and pops go away if I select a clock of 44.1kHz. The clock source on the Q20 is set to the optical input clock speed sent from the QS8.1, so it would not be influencing the problem. Here's my hypothesis...the samples for the QS8.1 were developed with 16-bit 44.1kHz sample rates. As the 48kHz clock attempted to output the samples (or even to hold them in memory...this would be a typical sloppy circuit design if the programmers didn't code for sample drift), it would stray from the original bitstream by 3.9kHz. In effect, the sample volumes would occasionally jump from values of high to low volumes and values of low to high volumes. Certain samples, such as the organ sounds, have wave forms that offset themselves just enough to frequently fall within the 3.9kHz drift area. So with that in mind, I wonder if 48kHz should ever be used? The analog values are probably experiencing the same clipping problems, but they are probably masked by the way analog information is delivered. It could be 44.1kHz always produces better output.

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