[munosmario]

I am both fascinated and puzzled by Stereophile’s Wes Phillips review of the CDP-8 and Jason’s response to the jitter (and other issues) shown by John Atkinson’s measurements. Jason’s response stated that “…the basics of performance were addressed by design and have been applying our effort at listening and making decisions based on listening. Like Wes, we had not noticed any significant degradation in the sound, so we had no reason to look for jitter issues.”  That is quite valid an explanation for a design process based solely on listening…problem is that in Wes’s review, he says that  “NewForce claims that  jitter is practically non-existent” (I imaging during his review related conversations with Jason)….which it is also claimed in the promotional pages discussing the CDP-8’s unique transport technology in NuForce’s website. My puzzlement comes from comparing those claims of practically non-existent jitter with Jason’s explanation to John Atkinson’s jitter measurement findings!!  If jitter was not actually measured since it was not considered as a key objective criteria in the ultimate design of the CDP-8, how could NuForce possibly claim that jitter is practically non-existent  (in review discussions,  but particularly in its promotional literature for that unit)?  I think a claim that unit was defective would have made more sense, resulting less puzzling and avoiding casting a shadow of doubt over NueForce’s published technical specs/measurements claims.
 
Sincerely………………………..munosmario

[worldcat]

Welcome to high-end Audio!  There is a lot of BS in audio and you must take the stereo magazines with a grain of salt as well.  I like the sound of Nuforce products and i believe their products sound like live music. 

[munosmario]

Welcome to high-end Audio!  There is a lot of BS in audio and you must take the stereo magazines with a grain of salt as well.  I like the sound of Nuforce products and i believe their products sound like live music.

Hi, worldcat...sorry, but issue is not with what is said in Stereophile but with what NuForce says in its promotional literature's technical pitch about  jitter in the CDP-8 ("virtually non-existent") versus what NuForce said to Stereophile in response to the extremely high jitter messured by John Atkinson, namely, that because unit sound was fine, they did not thought necessary to measure jitter...do you follow? If they did not  measure jitter because they did not find it necessary, how could NuForce possible claim that jitter is "practically non-existent"? It is like a designer of a single-end triode amp claiming that distortion is  practically non-existend and when a reviewer finds significant distortion, the manufacturer's explanation is to say that they designed the amp by listening and that they actually did not measure distortion. Don't you agree? That , of course, is independent of subjectively how musical is the unit in question...it is simply about credibility of the manufacturer's claimed measurements: if you are not measuring something, you cannot claim any measurement on  that something...simple logic IMHO

munosmario

[worldcat]

I understand but maybe they thought it would be no jitter because it stores the info before playing.  There was 3 different write ups on the cdp-8 in stereophile.  All in all the unit sounds good.

[munosmario]

I understand but maybe they thought it would be no jitter because it stores the info before playing.  There was 3 different write ups on the cdp-8 in stereophile.  All in all the unit sounds good.

worldcat, evidently the SQ of the CDP-8 is beyond question. What is amazing is that despite the high amount of jitter and noise modulation measured by John Atkinson, the unit sonded as good as repoerted by Wes Phillips...if that premise is accepted, then, you may be led to conclude that high jitter and noise modulation are not such a bad thing after all, or all that relevant for SQ

The second unit submitted to Stereophile for measurement have only been modified to reduce EMI and RFI radiation and that, according to John Atkinson, "worked to eliminate the noise modulation and reduce jitter." But, given that measurements appear not to correlate with SQ here, did that modified second unit reviewed by Stephen Mejias sounded just as good or better (or, maybe, not as good) that the first one reviewed by Wes Philips? We cannot tell given that the two units were reviewed by two different people (at different times and places, etc.). We can sweep all this under the carpet and  declare it as part of, as you called it, the BS in high end audio, or wait for some illuminated soul to throw some light on subject for us

munosmario

[rollo]

  What is all the nitpicking for ??? So it measured jitter. It sounds wonderull. Now maybe better. Details, details. 


charles

[munosmario]

  What is all the nitpicking for ??? So it measured jitter. It sounds wonderull. Now maybe better. Details, details. 


charles

Very illuminating, Charles...thanks.

[munosmario]

Very illuminating, Charles...thanks.

I did find something truly illuminating on subject (sorry, Charles)...at Anedio Audio's website:

QUOTE:
Measuring Jitter
We have intentionally left our jitter specification blank. It's not because jitter is unimportant. On the contrary, we care deeply about jitter because it produces non-harmonic distortion, which is the reason they are perceived as fatiguing, metallic, and harsh. However, to measure it reliably down to the picosecond level (one trillionth of a second) remains exceedingly difficult, and even if it could be done, a single number is inadequate unless its frequency-domain behavior is also understood. So rather than attempting to present a singe definitive number, we limit ourselves to presenting certain characteristics of jitter that seem relevant to auditory perception.

Sometimes, the jitter of the master clock is presented as a performance metric of a DAC. But it merely represents a lower bound, not the actual sampling jitter of the DAC. What we're really after is the sampling jitter, measured at the analog output of the DAC, which is what ultimately matters to the sonic quality
UNQUOTE

munosmario