there is some misinformation in one of the posts above:-
>> Depending on which "experts" you believe it is either
>> still a problem today or ....
yes, it still remains a problem today esp. in inexpensive CDPs & DVD players of which there are plenty in the market.
>> it is something that was caused by poor clock design
>> circuits (or sharing of clocks) in the distant past of
>> digital circuit designs like the early CD.
yes, it was caused by poor clock design (one of the reasons was using a high variable xtal for the clock source to keep BOM cost down) in CDPs of yester years. It remains an issue (maybe to a lesser degree) today.
>> In theory over sampling is meant to drive jitter
>> problems well outside the audible band where it can be
>> filtered out.
this is clearly not right! You seemed to be on the correct track citing clock designs & then ........... where did you pull out over-sampling to alleviate jitter?
Over-sampling was introduced to reduce the analog filtering requirements post-DAC.
>> Also, accurately clocking things out using a buffer
>> with a dedicated and accurate clock is cheap....
well not cheap enough for Magnavox ($35 at Walmart) or CyberHome ($38 at BestBuy) to put a highly accurate clock in these DVD player models!
Cheap is a relative term - you'll probably find a good quality clock in some "ES" Sony model & other models costing several 100 dollars. So, yes, if you are one to consider a $600-$1200 DVD or CD player to be cheap, you have a higher probability of being correct.
>> ....as the jitter creates low level frequencies that
>> were not in the original signal.
by low level, I assume you mean "low amplitude"?
Jitter raises the overall noise floor of the instrument thereby masking lower level details.
>> The problem is exacerbatted if jitter is significant
>> and repetitive (as opposed to random)
since we are talking audio here where the jitter issues are almost always clock related, jitter in audio is always repetitive. It is described as periodic jitter or cycle-cycle jitter. It is quantified as RMS jitter or peak-peak jitter.
>> This should not normally be the case with most recent
>> designs, even low cost ones.
How very mistaken are you!!
I personally do not think that there is a "sound" to jitter per se. Maybe there is but I have never heard it. What I've heard is its manifestation: loss of low-level details, reduced D.R. - music loses its snap, imaging not being precise, high freq being edgy/sharp/brittle.
>> Depending on which "experts" you believe it is either
>> still a problem today or ....
yes, it still remains a problem today esp. in inexpensive CDPs & DVD players of which there are plenty in the market.
>> it is something that was caused by poor clock design
>> circuits (or sharing of clocks) in the distant past of
>> digital circuit designs like the early CD.
yes, it was caused by poor clock design (one of the reasons was using a high variable xtal for the clock source to keep BOM cost down) in CDPs of yester years. It remains an issue (maybe to a lesser degree) today.
>> In theory over sampling is meant to drive jitter
>> problems well outside the audible band where it can be
>> filtered out.
this is clearly not right! You seemed to be on the correct track citing clock designs & then ........... where did you pull out over-sampling to alleviate jitter?
Over-sampling was introduced to reduce the analog filtering requirements post-DAC.
>> Also, accurately clocking things out using a buffer
>> with a dedicated and accurate clock is cheap....
well not cheap enough for Magnavox ($35 at Walmart) or CyberHome ($38 at BestBuy) to put a highly accurate clock in these DVD player models!
Cheap is a relative term - you'll probably find a good quality clock in some "ES" Sony model & other models costing several 100 dollars. So, yes, if you are one to consider a $600-$1200 DVD or CD player to be cheap, you have a higher probability of being correct.
>> ....as the jitter creates low level frequencies that
>> were not in the original signal.
by low level, I assume you mean "low amplitude"?
Jitter raises the overall noise floor of the instrument thereby masking lower level details.
>> The problem is exacerbatted if jitter is significant
>> and repetitive (as opposed to random)
since we are talking audio here where the jitter issues are almost always clock related, jitter in audio is always repetitive. It is described as periodic jitter or cycle-cycle jitter. It is quantified as RMS jitter or peak-peak jitter.
>> This should not normally be the case with most recent
>> designs, even low cost ones.
How very mistaken are you!!
I personally do not think that there is a "sound" to jitter per se. Maybe there is but I have never heard it. What I've heard is its manifestation: loss of low-level details, reduced D.R. - music loses its snap, imaging not being precise, high freq being edgy/sharp/brittle.
