On Tue, 2005-12-13 at 19:06 -0800, seanadams wrote: > pfarrell Wrote: > > Could be, but I have not seen a credible definition of what jitter is, > > how jitter is caused, what fixes it, or how jitter effects sound. > The first three are well defined and understood.
Maybe if one is as smart, talented, and good looking as Sean. > Jitter is critical in > high speed logic circuits and communication systems, and there are many > books explaining the phenomenon and how to manage and reduce jitter. I understand that it is about timing errors in the signal. But 44.1kHz signals, even the 1.5mHz signals that are all that red book is, is hardly high speed to you Silicon Valley guys. Three orders of magnitude, ok that is getting to be high speed. Four or five orders of magnitude, sure. Audio frequencies? Even as SACD/DSD the rates are not high frequency to any decent engineer. Where is the challenge? > There are also plenty of instruments offering different ways of > analyzing jitter. And Stereophile publishes nice charts every month. They do the tests for lots of digital gear. > Audibility (at the picosecond level) is nebulous, Which is exactly where I came in. Its easy to measure. It is talked about a lot. Is it important for RedBook audio? If it is important, at what values of which metric is it important? While the standard temperature for healthy humans is 98.6 degrees Fahrenheit, medical folks don't worry if it reads 99.0. Or even 99.9. At 100.0, you don't have a fever. So we measure it but don't care about some range of values. Seems to me that nearly all measurements have similar ranges that are insignificant, and others that are important. > but I am no longer > surprised at the things some trained ears can pick up on a good system. Humans have evolved for a long time to pay critical attention to phase and frequency. It meant telling where the lion was. But audiophiles also love tube gear, which any engineer knows has bad bandwidth (aka rolloff, aka warmth) and all sorts of intermodulation distortions. I'd love a cite to some science or engineering about the meaning of jitter at audio frequencies or redbook data rates. -- Pat Farrell http://www.pfarrell.com _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
