[temhem]

Can someone please explain me the difference between a good transport and a bad one. What are some things that could go wrong? All a transport is doing is reading a cd and dumping the 0-1's at a correct rate. From what I see, those are the two things you can screw up. I am sure that even the cheap players can read a clean cd quite accurately. So what am I paying for when I buy a 8000 dollar transport. I am sure it is not only to impress girls/boys.

 

[TravelLite]

Clock-related jitter is an important consideration, but of course it's certainly not the only one.

Even though the following short article has a commercial bent, it's not a bad introduction on the subject of a CD player's clock accuracy. In particular, note the references to "parts per million".

Right on Time - How the Trichord Clock Works:
http://www.trichordresearch.com/review_clockworks1.html

TravelLite

 

[temhem]

Thanks, that was a good read.

 

[Glassman]

the ones and zeroes are read and sent correctly on vast majority of things that can read CDs.. the only concern is their precise timing, which then in fact drives the actual D/A conversion in the DAC box.. period..

 

[JaZZ]

I don't think jitter is the only explanation for sonic differences with CD transports, if it's the main reason at all. One of the best universal players available with best ratings for all three audio formats, the Teac/Esoteric DV-50, has one of the lousiest jitter spectra I've ever seen.

I own two CD transports: Audiolab 8000CDM (a pure transport, ~$1800) and Philips DVD 963 SA (a DVD-CD/SACD player, ~$400) to feed my Bel Canto DAC2 with data. And guess what -- the Philips sounds much better, much more detailed and lively. At the same time I'm pretty sure that the CDM 12.4 drive in the Audiolab shows a similarly clean jitter spectrum as the Philips drive in the 963 SA. So what else could be the cause for the sonic difference?

 

[Canman]

Perhaps the digital receiver chip that translates the PCM signal into S/PDIF has something to do with it, as I believe that error correction is done in this stage.

 

[JaZZ]

Don't you think the jitter is measured on the S/PDIF output?

 

[Glassman]

it's clock clock and clock.. you have some oscillator driving servo chip, then you have the same (polluted) clock driving S/PDIF transceiver, which may vary in quality, then you have some kind of media to transfer it and on the end you have S/PDIF receiver reconstructing master clock out of the S/PDIF stream.. each stage should add minimum jitter it can, some do, some do not..

the ultimate solution is having FIFO buffer in DAC box and reclocking all incoming data with clean clock from very high quality oscilator..

 

[JaZZ]

Quote:

Originally posted by Glassman it's clock clock and clock.. you have some oscillator driving servo chip, then you have the same (polluted) clock driving S/PDIF transceiver, which may vary in quality, then you have some kind of media to transfer it and on the end you have S/PDIF receiver reconstructing master clock out of the S/PDIF stream.. each stage should add minimum jitter it can, some do, some do not.. the ultimate solution is having FIFO buffer in DAC box and reclocking all incoming data with clean clock from very high quality oscilator..

Sure...

...but what's the cause for the sonic differences between two transports with the same perfect jitter spectrum?

 

[Joe Bloggs]

Quote:

...but what's the cause for the sonic differences between two transports with the same perfect jitter spectrum?

Placebo?

 

[JaZZ]

Quote:

Originally posted by Joe Bloggs Placebo?

Sounds plausible, but only if you deny sonic differences with transports at all or are ideologically bound to the jitter explanation. No, the difference is very obvious.

I have done a blind test with my non-audiophile son, and he immediately noticed it.

 

[J.Y.]

Maybe the slight impedance mismatch at the digital output can result in this difference?

 

[AdamZuf]

bump

 

[Joe Bloggs]

Quote:

Originally posted by JaZZ Sounds plausible, but only if you deny sonic differences with transports at all or are ideologically bound to the jitter explanation. No, the difference is very obvious. I have done a blind test with my non-audiophile son, and he immediately noticed it.

How?

 

[Edwood]

Nice Pics, JaZZ.

Are there more jitter measurements like that for other transports?

Would be neat to see how different transports stack up to each other.

I'm curious to see the jitter readings from an NEC CD-rom (602, 602, or 3xp) I've been rather obsessed with those cheap 'lil bastards lately.

-Ed