What does Jitter sound like?

Gonzalo,

In Digital copy generations, there is no more Jitter in the 2nd generation than there is in the 100th generation, since every time you repeat the loop you go back to the hard disc and all the Jitter that the laser added is again gone. Jitter only has meaning during the real-time ADC procedure or the real-time ADC procedure. Other than that, you can send Digital files to CD's, Flash Drives, up to the Mars Rovers and back again, and then burn your CD and it will have the same amount of Jitter if burned under the same circumstances as your first copy.

Actually, many people burn copies of CDR's because they are making a copy which is even BETTER than the original white CD, because after they burn it, the CD playback mechanism reads it (for various reasons) with less Jitter, given a signal to the DAC with less Jitter, which sounds better.

These various reasons include the substrate material, reflections, focussing, vibrational issues, etc.

Liudas

Liudas,

True. Physically Jitter can ONLY exist once there is some form of clock or timing device...so a CD cannot have any jitter, however, if there is difficulty for a CD player to read a disc then perhaps oscillations in the drive motor power or lens focussing power might somehow cause the clock to be in error or more jittery (say for example they share the same power supply which happens to oscillate due to lens motor fluctuations, as it struggles to read a warped or uneven disc).

Shardorne, yes, you are right. I'm not too sure about the warped or uneven disc causing Jitter, though. My extensive experimentation shows that it is not this slow visible-to-the-eye movement of the lens which causes the Jitter one hears. Indeed, you can even put your finger onto a turning disc and you can cause a lot of low-frequency vibrations that way, but it isn't audible. What is audible then is if you go too far and cause a digital error. But Jitter itself is of a much more high frequency nature, as you say, such as from electronic oscillations and RF noise induction and the like.

Liudas

Shadorne - the positions of the pits in the CD are a form of timing information that can cause jitter as they are read. How this affects the PLL/buffering in the CD player depends on the design of the CD player. It is evidently important though. Rewriting a disk on CD-R with low jitter is an audible improvement on virtually all CD players I have tried. I mod a LOT of transports and players, so I get to try many different ones. This is good evidence that the pit locations are actually important.

Steve N.
Empirical Audio

Steve,

I woudl refer you to Nika Aldrich "Digtal Audio for teh Audio Engineer"

Quote:Page 353 "A digital recorder will store exactly the same information regardless of how jittery the clock"

Therefore according to Nika it makes no difference how many recordings or re-recordings or CD-R's you make.....ONLY a conversion to Analog or to Digital (where a clock is necessary) does jitter enter (from the clock).