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Jitter Question on Dual Deck CDR

Hello everyone, here is a question for those of you who know a lot about digital "jitter" in CD components. I have a dual deck audio cd burner that I use to make copies of my CD's onto CDR, and lets assume that the deck introduces some jitter into the newly created CDR. Now if I play back the CDR on (a) my CD transport, through an anti-jitter device such as AA DTI or SF ultrajitterbug, then to D/A, or (b) through a low jitter CD player, (question:) is the jitter on the source CDR removed/ameloriated or is it too late since the jitter is present on the source CDR itself rather than introduced during playback which seems what most jitter solutions are addressed at?
whew, that turned out to be a long question
- thanks
- John
south_park
sean
6,229 posts
 
Good question. I'm hoping that someone that is "digital literate" will help us both out. I was wondering something similar as i was thinking about having my dual deck burner "modified". Sean
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gboren
143 posts
 
Whatever distortion introduced in a CDR after a digital to digital reproduction, it is not jitter. By definition, jitter is the noise introduced as a result of clock inaccuracies in the D to A or A to D process.

I suspect there might be some debate about whether noise can be introduced in a D to D copying process where there is no format conversion. I would contend there is no noise introduction by virtue of the copying process alone. It is true that the "bits is bits" school has had to re-evaluate the theory with respect to the introduction of jitter by a digital transport in what is ultimately D to A process (or, more accurately, D to D to A). But that is because a clock inaccuracy in the transport will translate directly to an inherent inaccuracy in the timing of the "bits" that the DAC receives, hence, more jitter.

When copying from D to D, assuming the same format, "bits is bits" still holds. Two CD disks have rigidly located physical "pits" wherein the data is stored. When a copy is made, the disks are essentially identical. Of course, alignment and sampling inaccuracies could result in occasional "drop-outs", but that is not jitter and does not sound like jitter. An isolated "drop-out" would porbably be completely inaudible, and a profusion of drop-outs would sound like a lot of crackle.

Having said all that, if you WERE somehow able to introduce jitter in the D to D copying process, then that which sounds like jitter in the CDR is no longer jitter - it is part of the coded sound on the CDR and won't be dealt with as real jitter would. In fact, a jitter reduction process as part of a D to A process would work to preserve that sound while preventing any new jitter as a result of the current D to A process.
sean
6,229 posts
 
G, do you think that there would be any improvement by upgrading the passive parts i.e. caps, resistors, beefing up / regulating / filtering the power supplies in the D to D signal section ? Sean
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