What does Jitter sound like?

Dpac996, these are my personal observations going from stock oscillator in my SCD-1, through three generations of Audiocom Superclock up to SC4. In each modification, only the clock (or the clock power supply) were changed. I installed each clock myself & made the comparison within hours of deinstalling the previous clock. There was immediate dramatic improvement, and further improvement over up to 200 hours of break-in. If this is just "going for it" then so be it. There is enough controversy about measured jitter that I'll go with the evidence of my ears on this one.

No real answers so far....hmmm...

I agree...it is all pretty vague. However in fairness there are infinite possibilities and (for those who bother to study this) that "masking" is a huge factor in our hearing ablity...and sounds in proximity to other louder sounds are often inaudible unless they are a fair distance in frequency from the loud sound (several octaves being a fair distance)....all of which means that certain forms of jitter may be much more audible then other forms with, for example, random jitter being quite benign (nothing to worry about).

Still,....the above sounds like a Presidential Debate.

Shadorne,

Many decades ago my doctoral and post doc training was in psychoacoustics, particularly binaural processing. The concept of "critical bands" refers to a limitation of the resolution of the auditory system and the interaction of auditory stimuli. Needless to say, I take much of the claimed auditory observations with a grain of salt. Many theoretical differences that justify large expenditures do not conform with auditory reality.

From a telelogical perspective, our auditory system must be generalizer, otherwise it wouldn't serve us well. So of course explanations of the sound of jitter will be vague. After all, how many angels can dance on the head of a pin?

db

Dgarretson: great example of a controlled experiment. I wonder how much the improved clock circuitry reduced radiated emmisions, reduced injected noise into the ground planes, vs the degree it reduced actual clock jitter.
I'll always have a hard time understanding why nanoseconds of clock skew difference matter in most modern cd digital receiver front ends. I mean the digital data is clocked off the substrate then buffered (fifo) in the main cd dsp; inside this dsp, a new clock is generated and sent across the interface to the DAC. This buffer is pretty much crucial to good cdp function. I don't understand how jitter, as long as the set up and hold times of the actual registers are met, can be any kind of problem. I have never done a clock mod; do they instruct the modder to cut the (typical) crystal clock osc and insert the new clock signal there? is this only one point or do they also handle the clock to the actual DAC.

Another key feature to modern cd dsp chips is that the actual word (or frame) is entirely jitter free. Perhaps one could argue if the jitter is so horribly poor that individual bits are mis-sampled as they are clocked into the DSP, (then the overall value of the word is off), but that would have be a seriously poor design. Personally too much marketing emphasis is placed on jitter, I feel. The standard approach by all high end cd player designs is to implement an off the shelf DSP device (the thing that sits very close to the spinning disc and is responsible for servo, and data sampling, as well as microcontroller interface) and an off the shelf DAC. Some play games intermediate stages to decouple clocks and reduce skew, but in the end it's really just designing with building blocks that have existed since the 80s. Jitter is one aspect to all this but I think its contribution to the overall distortion spectrum is very miniscule w.r.t. all the other links in chain from pits and bits to volts.
I don't doubt that anyone hears a difference from a mod, but it's hard to distinguish between REAL differences and perceived ones based on expectations (after all the time effort and money went into it there better be a difference right?!). Anyway these are my personal experiences. It's all good fun.