The CD (or any other optical storage disk for that matter) is very jittery, because of material tolerances.
But all this doesn't matter at all. After the laser has read the information on the disk and an electronic digital signal has been created, it goes into a fifo buffer before going to the actual dac. The fifo buffer output and the input of the dac should be very close together, millimetres mater a lot here, and its this clock here that determines the performance of the dac.
And I agree with Marce: Jitter is a non issue in modern converters.
But all this doesn't matter at all. After the laser has read the information on the disk and an electronic digital signal has been created, it goes into a fifo buffer before going to the actual dac. The fifo buffer output and the input of the dac should be very close together, millimetres mater a lot here, and its this clock here that determines the performance of the dac.
And I agree with Marce: Jitter is a non issue in modern converters.
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With a small modification - "Jitter is a non issue in modern properly designed converters". Seems there are some pretty strange audiophile "designs" out there.
I am not saying jitter is not a problem and I am not saying it is voodoo, what I am saying is; is it as bad as some make out in audio, I see figures in ps, often must smaller than I have seen for other fields of electronics.
Personally I don't use CD transports any more I have all my CD now ripped to hard drive, as I think it is a better option...does It sound better, I perceive so...
My argument is that getting a few bits of data down a metre or so of cable should not be that hard, and if different drive sound different then there is a serious engineering problem in the chain.
Hiya Julf, gutted another engineer is in Belgium (so no Christmas market for me) as I was stuck working on a big job for these (and still am 4,000 connections analogue/digital layout!) HedoN, which I why I probably got confused over distance as these are near the port. Hopefully next year, though I am trying to get a visit to Hedon.
Personally I don't use CD transports any more I have all my CD now ripped to hard drive, as I think it is a better option...does It sound better, I perceive so...
My argument is that getting a few bits of data down a metre or so of cable should not be that hard, and if different drive sound different then there is a serious engineering problem in the chain.
Hiya Julf, gutted another engineer is in Belgium (so no Christmas market for me
) as I was stuck working on a big job for these (and still am 4,000 connections analogue/digital layout!) HedoN, which I why I probably got confused over distance as these are near the port. Hopefully next year, though I am trying to get a visit to Hedon.
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Hopefully this works.
http://amorgignitamorem.nl/Audio/Ji...ions due to jitter on digital audio 26_50.pdf
Or just copy this:
amorgignitamorem.nl/Audio/Jitter/Detection%20threshold%20for%20distortions%20due%20to%20jitter%20on%20digital%20audio%2026_50.pdf
Thanks - yes, that one talks about hundreds of ns even with trained listeners and ideal conditions.
These units are used by Meridian, Unison Research and last one by Plinius.
I had the chance to measure them and compare them with other units. So, yes, there is some subjective listening as well.
Regards,
Tibi
I have bad behaviur do not save my measurements, but now if you requested this I still have Plextor and Asus units and if time will allow I'll repeat jitter and bit accurate measurements to share here.
Regards,
Tibi
TEAC 5020A is another unit I have in my workshop. Good quality, reliable and sound also good.
Regards,
Tibi
CD transports don't have "a sound".
Its the DAC that matters, there the digital signal is converted into a signal we can listen to.
It could be that the DAC designer has no clue on how to properly design a DAC, witch happens a lot in high end audio. These awful DAC's have no jitter reduction build in like PLL's or ASRC and there it is very likely that you can hear a difference between transports. But its a faulty design and anyone interested in good sound should reject these devices.
I'm sure that by "good sound" erin want to say bit accurate and low jitter.
Regards,
Tibi
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