[hciman77]

Quote:

Originally Posted by Dept_of_Alchemy /img/forum/go_quote.gif Is transport jitter a concern anymore nowadays with jitter-immune DACs being so common? The DAC1, for instance, claims 'complete' immunity to transport jitter and seem to have the numbers to prove it...

Nobody in the whole world has to my knowldge been able to prove that jitter below 20ns is reliably audibly detectable in music, for single high frequency sine waves the level is 10ns. Jitter does raise the noise floor and decrease effective bit-depth, but it has never been shown that the jitter in any half-competent audio component is at a level that causes audible degradation. The worst jitter ever clocked for a CD playing device is 4ns. There are several peer reviewed articles out there that have tested jitter audibility under controlled conditions using high quality components. For deterministic jitter 20ns seems a problem for random jitter levels can go into the 100s of nanoseconds before it is detected. I really would not worry about jitter, death and taxes yes, jitter no

 

[philodox]

I've always found this article informative.

http://www.aoselectronics.com/jitter_article.html

 

[artizen65]

http://www.positive-feedback.com/Issue22/nugent.htm#top

This article is also quite informative.

 

[hciman77]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif I've always found this article informative. http://www.aoselectronics.com/jitter_article.html

Quote:

Originally Posted by artizen65 /img/forum/go_quote.gif http://www.positive-feedback.com/Issue22/nugent.htm#top This article is also quite informative.

The causes and effects of jitter are well documented, there really isnt much controversy there. The only issue of relevance in audio concerns the extent to which jitter causes audible degradation, and the results of all controlled listening tests conducted so far indicate that below 20ns jitter just doesnt cause audibly detectable degradation in music.

I think one reason why the idea of jitter being a non-issue is controversial is that high jitter lowers effective bit-depth. This means that in tests people cannot tell the difference between 16 bit and 15 bit or even 14 bit samples. For years some have been maintaining that 16 bits just isnt good enough as a replay medium, paradoxically some of these same folks happily listen to vinyl whose capabilities in terms of noise and Dynamic range are below 16 bits. The results of jitter listening tests seem to provide some evidence that 16 bits is actually better than we really need for normal replay.

 

[philodox]

Quote:

Originally Posted by hciman77 /img/forum/go_quote.gif The only issue of relevance in audio concerns the extent to which jitter causes audible degradation, and the results of all controlled listening tests conducted so far indicate that below 20ns jitter just doesnt cause audibly detectable degradation in music.

Can you point me to such a study? I've seen some in the past, but there has always been something about the ones I've looked at which caused me to discount the findings.

 

[hciman77]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Can you point me to such a study? I've seen some in the past, but there has always been something about the ones I've looked at which caused me to discount the findings.

Sure, this is the latest one I know about

http://www.jstage.jst.go.jp/article/...26_50/_article

the same authors did another similar paper but it is in Japanese. I had some conversation with the lead author (Dr Ashihara), he basically told me that while people do vary greatly in their ability to detect jitter he simply said that if somebody told you they could detect jitter in the 150ps range - dont believe them. Their studies (2) didnt find detectable jitter below 100s of nanoseconds.


The Benjamin and Gannon paper is the one that found the lowest detectable levels i.e 20ns of deterministic jitter giving rise to sidebands. Sadly it and some others of these refs are AES and that means you have to pay for them

REFERENCES
[1] E. Benjamin and B. Gannon, ‘‘Theoretical and audible effects of
jitter on digital audio quality,’’ Preprint of the 105th AES
Convention, #4826 (1998).
[2] K. Ashihara and S. Kiryu, ‘‘Simulation of sound degradation
due to time jitter on digital audio,’’ J. Acoust. Soc. Jpn. (J), 58,
232–238 (2002).
[3] K. Ashihara and S. Kiryu, ‘‘The maximum permissible size and
detection threshold of time jitter on digital audio,’’ J. Acoust.
Soc. Jpn. (J), 59, 241–249 (2003).
[4] S. Kiryu and K. Ashihara, ‘‘A jitter simulator on digital data,’’
Preprint of the 110th AES Convention, #5390 (2001).
[5] T. Tomizawa, H. Ohtake and J. Ohga, ‘‘Effect of jitter for
listening by a few musical signals,’’ Proc. Spring Meet. Acoust.
Soc. Jpn., pp. 703–704 (2003).
[6] A. Nishimura and N. Koizumi, ‘‘Measurement of sampling jitter
using a musical signals,’’ Preprint of the 114th AES Convention,
#5797 (2003).
[7] A. Nishimura and N. Koizumi, ‘‘Measurement and analysis of
sampling jitter in digital audio products,’’ Proc. ICA 2004, IV,
pp. 2547–2550 (2004).
[8] K. Ashihara and S. Kiryu, ‘‘Linearity evaluation of loudspeakers
and headphones,’’ J. Acoust. Soc. Jpn. (J), 56, 713–720 (2000).

 

[bordins]

Thanks, hciman77.

 

[stryker]

Benchmark's DAC1 jitter-immunity claim is not true to me. I have used different tranports and find it does better with a low-jitter transport. Several other people have claimed the same outcome.

Numbers are all that come out of the clock. The extent to which the numbers are accurate effects the sound since a DAC is all about math and computing a number that then is assigned to a decible into an analog sound wave (or whatever it's called). That's why 24 bit sounds better than 16 bit. Jitter is an issue but...like everything else in life...it's all a matter of DEGREE.

The DEGREE to which jitter effects the sound of a DAC varies but as far as the DAC 1 and some other DACs do, jitter does matter. Most of us have a life and don't need perfection, we just need a high degree of sonic fidelity. I find that getting a source with as little jitter as possible is an important variable to me and is based on my own direct experiences. I encourage everyone else to find out themselves rather than rely on the opinions of others.

 

[DJShadow]

Quote:

Originally Posted by stryker /img/forum/go_quote.gif Most of us have a life and don't need perfection, we just need a high degree of sonic fidelity. I find that getting a source with as little jitter as possible is an important variable to me and is based on my own direct experiences. I encourage everyone else to find out themselves rather than rely on the opinions of others.

Well expressed. Its something that needs to be remembered at all times as there are definitely people here who might be put off purchasing a particular piece of equipment because of a member's/members' bad experience. Sometimes we forget that hearing isn't homogeneous and is just as subjective as our tastes in music, which is what this hobby is all about.

I'm currently winning a bid on a NAD C542 and hopefully have a Gilmore Lite as well. What interconnects will I need?

In the meantime, please continue this discussion

 

[hciman77]

Quote:

Originally Posted by DJShadow /img/forum/go_quote.gif I'm currently winning a bid on a NAD C542 and hopefully have a Gilmore Lite as well. What interconnects will I need?

Bog-standard RCA to RCA leads will do the job.

 

[artizen65]

http://bluejeanscable.com/store/digital-audio/index.htm

Approx. $20.00 with shipping. Execelent cable.

 

[DJShadow]

I won that NAD which represents my progression from crappy portable sources to true audio equipment; no its not high-end but I like to see it as being a reasonable step-up at least

. It also comes with some QED Qunex cables but I don't know how much they're worth or if they're any good.

 

[Killercrush]

Quote:

Originally Posted by philodox Which CD player? Sounds interesting.

The Harman-Kardon HD970 http://www.harmankardon.com/product_...70/230&sType=C

 

[HiWire]

Congrats on the NAD... I'm waiting to see if there is a C545 in the near future.

 

[spacecoyote]

I am now completely divided between two players:
Fully modded Music Hall CD25.2
or
Mini modded Shanling CD-3000
(both from Walt at Underwood/pcX)

Anyone feel like making the decision for me? Seriously...