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does SPDIF allow lossless and no processing from computer> - Page 2

post #16 of 17


 

Quote:
Originally Posted by nick_charles View Post

 

You are aware that jitter-worriers will just say that you only adding jitter to existing jitter and that the 5400 is so high in jitter already that it is not a meaningful test as the damage has already been done


And this is indeed a valid observation, as long as I didn't tell if the listeners found the 100 ns jittered source to sound good or bad compared to a low-jitter source.

 

WHat would have been interesting is correlation between added jitter and distortion at the DAC output. In the Prism paper about the sound of CD pressings, Dunn / Dennis / Carson said that they had to tamper with a DAC in order to make visible the effect of incoming jitter at the analog output. Otherwise, the DAC completely removes the incoming jitter. They also made a very interesting observation : the distortion measured as jitter by Bruno Putzeys in the analog output of his CD player might very well have been amplitude modulation, and not jitter. Both look the same on spectral plots.

They found amplitude modulation to depend on the physical CD instered in the CD player, without any relationship to pressing quality (in terms of pit/land jitter), CD factory, and the dependance was not present in separate drive / DAC systems.

http://www.prismsound.com/m_r_downloads/cdinvest.pdf

 

Quote:
Originally Posted by nick_charles View Post

 

Steve (not only can I hear 2ps of jitter but I can hear the differences between different 2ps jitter spectra) Nugent may take you to task on this...

http://www.head-fi.org/forum/thread/407522/external-hd-airport-extreme-mbp-airport-express-esoteric-dac/15#post_5397633

 

His observation about the kind of jitter is valid too. In that listening test, it was not said what kind of jitter was used, nor the model of the jitter generator (I can ask, if someone is interested).

 

However, the point is not very important as long as

-Measurements in the analog output does not show significant distortion

-Blind tests between CD players and DACs fail.

 

I recall that so far, successful ABX tests were done with

-Non oversampling DACs (treble loss)

-Lossy compression anti-shock buffer in a portable CD player

-Wrong playback speed in a portable CD player

-Background noise in a 30 € DVD Player

-Wav vs looped DA/AD recording of the same wav (through CD Players as well as soundcards).


Edited by Pio2001 - 8/29/10 at 7:28am
post #17 of 17
Quote:
Originally Posted by nick_charles View Post

Thanks for that. 100ns is a lot of jitter !


By the way, 100 ns is the amount of jitter where one raw bit in the S/Pdif stream takes the place of the next or previous one.

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