Jitter is not audible, sighted and blind tests. - Page 2

Well if you have to train your ears to hear jitter, why would you do so? Just to spend money on removing it afterwards?

Easy, to let other people sell you their "state-of-the-art" digital cables and other jitter-reducing equipment

I thought the conversation was about jitter in a usb and spdif, and given that the spdif format simply can not tolerate 177nsec jitter. So I pointed that fact out.

I am not sure what those guys were doing. It seems to me that they pre distorted the signal to emulate the effect of jitter. The paper did not have enough detail.

Well, something is way off here. You can find credible double blind listening tests where people could hear far bellow 1 nsec jitter. There is some good material out there, and I would start by looking at papers by Hawksford and Jullian Dunn. Don't you think that tt is remarkable to have such a huge differences in findings?

Regards
Dan Lavry

Dan, do you have a reference for these sub-ns listening tests, I am genuinely interested, Dunn's jitter work was centered on mathematical models of audibility, Dunn never did any controlled listening tests, I do not think the good Dr from Essex has either afaik, but Benjamin and Gannon who are perhaps more recognized than Ashihara did and they still found thresholds in the 20ns region for signal correlated jitter. Even if we disregard Ashihara and colleagues US empirical research (Dolby Labs) seems to put the thresholds well above 1ns.

Nobody is disputing the objective damaging effects of jitter , the big question is how bad does it have to be before we can actually hear it.

"Nobody is disputing the objective damaging effects of jitter , the big question is how bad does it have to be before we can actually hear it. "

thats what i looked on this thread for. wished i hadn't now. all this is waaay above my head!

LOL - if it is any comfort I have been trying to track down a definitive answer to this question for over 3 years and so far the only controlled listening tests that I have found after rigorous searching *ALL* put the thresholds way above what you would actually get in commercial audio gear, well gear that was not utter pants anyway

Paradoxically the very worst audio device out there , for measured jitter according to Stereophile, is the not inexpensive McIntosh Music server , well I'll go to the foot of my stairs

Nick
thanks for that comment , you just saved me hours of searching.
i shant dwell on the jitter subject any longer.

I need to spend less time on the web, but given that you have been looking for a “jitter number” for a long time, let me suggest again to review Hawksford paper, and also Adams paper.

http://www.essex.ac.uk/csee/research...e%20flawed.pdf

I do not have a link for Adams paper but I believe you can find it.

There is much to be read in that articles. Much of what Hawksford and Dunn did and talked about does have to do with keeping the jitter "below the threshold of audibility", not some made up figures but pretty well known levels for what real people can hear. As always, follow the references at the end of the paper…

And I also highly recommend reading “Clock Jitter, DA Converters, and Sample –Rate Conversion” by Robert Adams published at the Audio Critic (or better yet, for any AES members, look for print # 3712). Bob Adams is an exceptionally brilliant engineer, highly respected by the engineering community!

If nothing else, you may gain some understanding WHY there is no single number for jitter audibility.

In Adams paper, he explains why a 1 bit 64fs (such as DSD) is vastly more susceptible to jitter then say a multi-bit sigma delta with a switched cap output stage. You will see that a resistor based R-2R DA has a different sensitivity to jitter… Add to that the facts that the type of jitter plays a role, and the frequency content for each type also plays a role.

You can not have a meaningful single number for jitter audibility. There are too many variables, from jitter type and content to circuit architecture. In my view, the folks that do come up with papers, listening tests or comments ending with a single universal jitter number, are in fact showing much lack of depth regarding the subject of jitter.

Regards
Dan Lavry

I have this paper (or a close variant) but it is worth pointing to anyway.


This is a different Dunn by the way C not J. Also I never referred to Dunn or Hawksford making up figures , I refer them to using models, this is not the same thing, however these figures are still predictions based on models. I do not think they fully take masking into account but even if they do they are yet not supported by listening tests with humans, this is the gap in knowledge. And an opportunity for someone to get a handful of easy AES publications


Know it, agreed, nice paper and very useful for debagging Stereophile magical thinking journos. But iirc Adams makes the point that separately measuring jitter may be (mostly) unnecessary as it will manifest in downstream distortions anyway ?


Well as I say above, this is would look like an excellent opportunity for someone to make a name by carrying out some serious listening tests varying one thing at a time in the established empirical tradition.

A good starting point though might be blind tests of some add-on jitter reducers.

To say there are too many variables and leave it at that allows manufacturers of specific jitter devices to escape from the imperative to prove their claims ?

Would you say D4 is similar to D10

Not sure if I need to spend extra cash on D10 as it looks like multi-interface is the strength of D10 but I notice the chips used are different. Is the D10 sonically superior to iBasso D4 Mamba in your opinion?

There is one device that gets to over 11ns. I guess we cannot say jitter is definitively always inaudible without more testing but all the controlled listening tests with whatever methodological issues they may have to date do point in the same direction... i.e the don't worry about it direction.

The McIntosh Music Server.