Digital Drive

RE: Jitter

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This Post Has Been Edited by the Author

In Reply to: RE: Jitter posted by Tony Lauck on June 02, 2012 at 10:29:25

Ah, good point. After a little thought I see that every example I gave could be grouped under the heading of "Noise," and that jitter should be classed as "Distortion."

Is this a good way of thinking about it? "Noise" is inherent to the playback chain and is always present, while "Distortion" is error created by how the signal chain handles the music itself. I'm struggling to figure out how frequency response deviations fit into that paradigm, perhaps that's why they are specified separately.

Anyhow, being constant, Noise must be far easier to recognize than Distortion, which is only present as a shading to the music itself. I guess one of the benefits of Digital is a dropping of the noise floor to levels Analog recorders are incapable of. Certainly it's easy to tell my "AAD" recordings from my "DDD" recordings simply by the presence of the tape hiss in the former. I suspect, though I don't know this for sure, that the Digital recorders also have a flatter frequency response than Analog recorders. I do know that the specifications for CD playback show a far flatter frequency response than that of any phono cartridge I've ever seen.

I'm still left wondering what "Jitter" sounds like. As it is a Distortion, I guess the question is tantamount to wondering what "Harmonic Distortion" sounds like. As you point out, the vary nature of Distortion makes it difficult to hear unless it's sufficiently high in level. I'm not sure I've ever heard Harmonic Distortion, perhaps because all the amps I've ever listened to have sufficiently competent circuits as to reduce it to the level of inaudibility. Certainly I don't sit up nights worrying about ways to reduce the Harmonic Distortion in my system!

If Jitter is just Distortion, then doesn't it follow that like any other Distortion it too could be reduced to the level of inaudibility? I guess to paraphrase the old question, "If a tree falls and no one can hear it, does it make any noise?" How soft does Jitter have to be before we can stop worrying about it? How loud does Jitter have to be before it becomes intrusive?

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