How many forms of Jitter can you identify?

Bombaywalla, thanks for the explanation.

The logical follow-up question would be how significant is all of this from a quantitative standpoint? The data on page 3 of the reference you provided addresses that question, although the various terms and quantities are not clearly defined. My interpretation of it is as follows:

1)Looking at the first two of the four tabulations, on average there were 0.00 uncorrectable errors in each 1 second block, both before and after demagnetization.

2)Looking at the last two of the four tabulations, the WORST CASE (across some unspecified number of disks, trials, etc., and averaged in some way) was that there were 0.22 uncorrectable errors per 1 second block, or in other words 1 interpolated sample approximately every 5 seconds (which would comprise approximately 450,000 16-bit samples for the two channels).

And what they are saying is that demagnetizing would reduce that worst case number of interpolated samples by about one-third.

The bottom line on audibility, IMO: I'll give it a "definite maybe," but from a personal standpoint I don't consider any of that to be sufficiently compelling to inspire me to go out and buy one.

Best regards,
-- Al

Al, no problem.

yeah, it's hard to say how quantative this particular effect is. It is a mechanism of jitter generation & it might not be significant in & of itself but combined with all the other hash in the signalling chain, it probably does contribute to the overall digital nature of CD playback.
In the A-R website they did show some plots of amplitude of wanted signals increasing after de-magnetizing & their claim was one could hear sounds not heard before during playback. Never tried one myself so I cannot comment but they are showing data to that effect.....
So, like many things - best to attack the jitter issues by addressing the largest perpertrators leaving only the minor contributors to be attacked some later day time &/or budget permitting.

I can't really identify jitter, but I know the heebie jeebies when I hear 'em.

When you listen to speed thrash metal, jitter does not stand a chance.

Many of Julian Dunn's classic AES papers on jitter can be found here, and are IMO required reading on the subject:
http://www.nanophon.com/audio/
Two big conceptual errors I see very commonly are the assumption that any intrinsic jitter related to retrieval of information off of a CD actually occurs through the forward signal/data path, and that any sonic artifact associated with parts upstream of the DAC must be classifiable as jitter.

In reality, CD players, transports, and DACs are a menagerie of true mixed-signal design problems, and there are a lot of different noises sources living in close proximity with suceptible circuit nodes. One oft-overlooked source is crosstalk from the disc servomechanism into other parts of the machine . . . analog circuitry, S/PDIF transmitters, PLL clock, etc., which can be dependent on the condition of the disc.

One easy way of measuring this on the test bench is to have two versions of the same test-tone CD, one pristene, the other scratched. A conventional distortion analyzer is used to null out the the tone(s), and then an FFT (or visual 'scope analysis) is used to analyze the residual. One would be suprised at some of the nasty things that sometimes come up out of the noise floor when the focus and tracking servos suddenly have to work really hard to read the disc.

But that said, demagnetizing a CD is of course silly. If it's scratched or hazy, I use a 3M product called "Finesse-It", which is sold as a professional polishing compound for automotive finishes. Sometimes spot pre-treatment with a Mr. Clean Magic eraser on particularly tough scratches helps, then Finesse-It to remove the scratches left by the eraser.