Axiom Home Page Forums General Discussion Stereo CD player vs DVD player

Jitter is measurable, and apparently audible. Here are some informative links I found by searching Google:

http://www.birdland.com/papers/jitter92.pdf (research article)
http://home.earthlink.net/~bobkatz24bit/jitteressay.html
http://www.stereophile.com/showarchives.cgi?112:7 (measuring jitter)
http://www.pcabx.com/technical/jitter_power/index.htm (listen to jitter)

-Cooper

Cooper,

Thanks for the links (especially the last one that contains sample sounds, which are interesting to listen to).

HOWEVER, you have to read all the "techy fine prints" before making these kinds of technical arguments. I emphasize this because the type of misunderstandings and confusions that you obviously exhibited is precisely what is used to create the MARKETING BS that I was referring to.

In a nutshell, you (and two of the links) are completely mixing up the "data link jitter" and "sampling jitter" (according to the terminology used in the first link) together. In fact, I already touched on the difference between these two things in my last post -- I said: "now, jitter introduced within the DAC circuitry is a totally different matter."

Anyway, several direct citations from your links suffice here...

From the second link:

Can Jitter in a Chain be Erased or Reduced?

The answer, thankfully, is "yes". Several of the advanced D to A converters now available to consumers contain jitter reduction circuits. Some of them use a frequency-controlled crystal oscillator to average the moment to moment variations in the source. In essence, the clock driving the D/A becomes a stable crystal, immune to the pico- or nano-second time-base variations of jittery sources. This is especially important to professionals, who have to evaluate the digital audio during recording, perhaps at the end of a chain of several Phase Locked Loops. Someday all D to A converters will incorporate very effective jitter-reduction circuits.

Remember, this essay was written in 1995-1996. Today, what the author regards above as techniques used in "advanced DACs" are utterly ubiquitous. EVERY one of today's DACs incorporates various architectures that make it more tolerant on both kinds of jitters. In particular, the data-link jitter introduced to the digital readouts (which is what you were talking about above) is a NON-ISSUE in today's standard, period.


From the first link:

Often sampling jitter is confused with data link jitter. They are linked because inappropriate clock recovery circuits are often used for deriving sample clocks from the interface signal - which will often have relatively high levels of jitter as a result of the information being carried. This data link jitter need not affect the quality of the finally reproduced signal - until it is so large that data errors are produced...

Again, this paper was written way back in 1992. This has already long been taken care by newer DAC circuitry. And this is one of the many reasons why newer DACs often sound better than >10-year-old ones.

Thank you very much for sharing your detailed analysis. I need to keep reminding myself not to spend too much on any one piece of equipment due to rapid technological changes that seem to make evrything obsolete in just a few years (maybe speakers, amps, and subs are the exceptions, no?).

Hey Sushi;

The DACs on you receiver definitely have great writeups and specs. You got me looking into my receivers and cd player DACs and this is what I came out with:

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What is the processor used in the RSX 1065?
The RSX 1065 utilizes a Cirrus Logic Crystal CS49326 for its processing and Dolby Digital / dts decoding.

What DACs and ADCs are used?
The RSP 1066’s DACs are the Ashai Kasei AKM 4324, and the AKM 5351 ADCs. The DACs are implemented as 24bit/96kHz, and the ADCs are utilized as 20bit/48kHz.

However, time moves on and when the original CD-63 was introduced, some marked Changes took place. First, Marantz ditched the Philips Bitstream DAC in favor of a part from NPC (an Epson/Seiko company). They also changed over to the linear-tracking CDM-12.1 Mechanism (still Philips) and implemented a different analog filter and Output Circuitry.
One of the (technical) Reasons I decided to buy the CD-67 SE (with a view to future modifications), was the NPC DAC used. This is a very interesting part, which seems to be a copy of the "original" Delta/Sigma DAC, the Crystal CS4303, a pretty old part that still nevertheless outperforms most current Bitstream DAC's.
ThanX to the friendly people at Farnell Electronic Components , who photocopied me the Datasheet of the NPC SM5872 DAC from their Databook (yup the whole 26 pages). This DAC Chip is very well designed. While it combines a crystal-oscillator, a digital interpolation filter (8 times Oversampling) and two Delta-Sigma DAC's on one Chip, all these components have separated power-supply and ground connections run out from the chip.
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The surround chips on the 1065 is in par with the rest out there. Supposedly 7 of 10 processors have this including the acclaimed Lexicon processor.
The DACs on the 1065 is kinda a question mark. The chip maker for the DAC does not even list it on there site. I noticed the DACs on surround/DAC OEM boards. So it doesn't look too promising. That is why I "think" and "sounds" my CD player DACs sound better than the RSX 1065 DACs.
The DACs on my Marantz was highly acclaimed maybe 8 years ago but with technology maybe it is dated.
I was thinking of the concept of going external DACs to improve stereo listening. ie. Bel Canto, Monarchy or Musical Fidelity DAC. Or should I just get a whole new CD player with good DACs.

Hi Will,

Well I tend to disagree with some of the prevailing wisdom here on the Axiom boards, so we like to duke it out when someone brings up a controversial topic. DAC technology does not advance very quickly in terms of sound quality; all the new products are just adding support for DVD-audio and SACD / DSD, I believe. DACs have most definitely evolved faster than speakers and amplifiers, but they are still subtle evolutions.

I am looking into the Denon 2900 DVD-V/Audio / SACD / CD player because of its good DACs all around. If you don't want to spend a lot, start off with a regular DVD player. After a few months, try listening to a good standalone CD player, and you be the judge.

-Cooper

OK Sushi, here we go again...

That's an awful lot of words to refute my two sentences. I just said that word-clock jitter can be introduced at the source, and that is correct. I have never encountered any useful information about jitter from any marketing source. Yes, there are multiple types of jitter. Bob Katz makes some clarifications on his jitter article, in response to some letters:

http://home.earthlink.net/~bobkatz24bit/jitterletters.html

Here's an interesting excerpt:

In reply to:

---

the apparent sonic differences between interface technologies such as Toslink, glass, and copper are IRRELEVANT when doing transfers or when passing signal from one processor to another. You can forget about that question with COMPLETE CONFIDENCE----since all of the technologies are capable of passing perfectly good data, within their specified cable lengths. Remember: the clock is not transferred along with the data. Only the data is transferred to the processor's circuits.

The apparent sonic differences between interface technologies come into play in only ONE place.... and that is at the input to the converters (A/D and D/A).

If the D/A is susceptible to jitter on its digital inputs (as most are), then you will hear differences between toslink (plastic fiber), glass fiber, and copper (hard wire). Some D/As reject jitter better than others, and that will determine the extent you can hear these differences. REMEMBER: This is only important to that particular listening session (the D/A only) and not to any other circumstance.

---

He's basically saying that "data link" jitter is wiped out when going from one digital processor to another processor, but that it directly affects the "sampling jitter" when going from digital source to an external DAC. The reason is that many DACs don't have jitter rejection for their digital source.

Do most modern, cheap DACs have strong jitter-rejection circuitry? It was noted that good power supplies have an effect on jitter, by the way.

-Cooper