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Thread: Audible Jitter/amirm vs Ethan Winer

  1. #41
    [WBF Founding Member] Ron Party's Avatar
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    Amir, I have 2 questions for now:

    1) I've read the description you've posted here and (in what seems like another lifetime) at AVS, and IIRC in all of the tests you've run you were listening through cans. Have you heard what you describe as jitter through loudspeakers?

    2) Whether or not the tests you've run may be properly characterized as DBT or not, they would appear to be of the AB variety. Have you correctly identified what you describe as jitter by passing an ABX test?

  2. #42
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    Amir said,

    """Putting it all together, jitter is indeed a small level of distortion. It is not a problem for the general public or those with very limited funds to deal with it. For discerning audiophile though, it should be a consideration. Investing in good gear with good digital hygiene, can help eliminate it, bringing digital closer to its ideal characteristic of being transparent to the source.""""

    I like the term good, "Digital hygiene, can help eliminate jitter..." I have been pealing away layers of distortion for 8 years, using the same speakers and amps. The solid sate amps I left behind were a big part of the problem. Later, preamp, cabling and source were all replaced with the test being hearing more within the recording.

    I have a rather rare disc, "Lavin," where the first notes are plucked from the strings of a grand piano. What you hear is anything your system can do. When you get those raw string sounds, their reverberations, and decay correct you know it, if you know pianos intimately.

  3. #43
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    Quote Originally Posted by Ron Party View Post
    1) I've read the description you've posted here and (in what seems like another lifetime) at AVS, and IIRC in all of the tests you've run you were listening through cans. Have you heard what you describe as jitter through loudspeakers?
    No I have not tested jitter using speakers. While we had a $300K+ listening room at Microsoft, I was always too busy at work to go and use it to run these tests. Instead, I would do the testing at home using my audio workbench which has a nice headphone amp with A/B inputs letting me do quick tests with minimal gear in the loop.

    I was asked once whether I thought it would be as easy to hear these artifacts with speakers and I said no. Happy to elaborate once we cover some of the main points of the debate.
    2) Whether or not the tests you've run may be properly characterized as DBT or not, they would appear to be of the AB variety. Have you correctly identified what you describe as jitter by passing an ABX test?
    No. It is difficult and expensive enough to run these tests as AB. While I have run countless ABX tests for other types of distortion using computers, doing so with CE hardware becomes very challenging for someone trying to satisfy personal curiosity. As it is, I had to buy two of many things from content to hardware. Think how you would structure ABX for yourself to run at home and you see the issues .

    To address your implied point and that of Glen, I have always readily admitted that my tests results are not fit for publication nor absolute proof of anything. But the opposite is also true that they canít be easily dismissed as sighted and clearly subject to bias. In addition, I usually find far more flaws in the tests of people who say they didnít hear digital audio artifacts than they find in mine . So until they raise the bar on what they do, I think I am fine stating my results as having value.

  4. #44
    I don't think there's any question that your results have value, Emir. Blind listening, no matter how informal and inconclusive, is always more objective than sighted listening. I don't even understand how people deny that. With that said, even as a very frequent headphone listener, I'm not going to concern myself much with a distortion happening that many db below the music. I think I can rest assured that I'll never hear it over the voices in my head.

    P

  5. #45
    I have read this debate with a great level of fascination. Although Ethan is a friend of mine, and we are often on the same page about audio issues of this nature, Emir presented a lot of meaningful facts which have merit.

    Some people MAY be able to hear certain distortions that others aren't trained to recognize. In a way, it's analogous to the existence of God. Some swear by the existence of God, others say they cannot perceive it therefore it does not exist.

    When Ethan presented his test of 3 digital recording systems last month, I was actually quite shocked that I could hear a difference between all three files (once he fixed his mistake with the duplicate files). While sorting out the low-end DAC was easy because of the noise, I discovered something different about the IMPACT in the recordings between the two higher end DACs. One had definate impact and the other was more restrained. I think I was hearing a difference in linearity of the two, causing subtle, but definate dynamics differences.

    Another more extreme example was my Ultimate Fireworks Video, which I recorded in 24-bits, on the launch site for a fireworks display. I played with this recording on 3 different systems. All were "high end" for their type of device. Two were internal computer cards. One of them sounded gritty and granulated to the point where it seemed like 100% THD on the preamble before the fireworks, which was peaking at -85dB in the recording. The National Anthem was playing on a car stereo, 600' away, along with other ambient sound from the middle of an airfield at Danbury Airport, where the launchers were situated. The other computer sound card did a much better job reproducing the ambient sound, though there was much noise and clock buzz, etc. Finally, the high end pro gear that recorded it was used to play it back, and once again it was like being there.

    With regard to jitter affecting s/n, this may explain why going from 24-bits to 16-bits with NO dither, resulted in the introduction of hiss where none was audible in the original 24-bit recording. Somewhere during the software conversion, there may be the equivalent of jitter being introduced into the resulting file, which is the only sensible explanation for this noise being introduced by merely converting the file to 16-bit. I experimented with all of the dither types and spectral shaping curves and eventually found a combination that was quieter than "no dither" on the converted file, but the introduction of hiss by merely converting the file was still somewhat baffling to me.

    DACs DO sound different, and often vastly so at very small signal levels. At normal music levels, they can definately affect the dynamics, as I discovered when listening to Ethan's 3 test files on my reference system.

    BTW, last month, the DAC on the left channel of my Denon DCD-590 started sounding 'tizzy' in the left channel and I troubleshot and played the disc on my Oppo and it sounded good again. So the DAC or some component related to it has gone south in the Denon player. It was audible with my Bridgeport Symphony recording that I produced in Nov 2008. Had I had on a pop/rock CD, it would have gone unnoticed.

    Anyway, great and stimulating debate guys!
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  6. #46
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    I just think it is important to be accurate. If what you're doing is sort of single blind testing controlled solely by yourself, call it that and don't assert that you've done double blind testing.

    And, I agree, the results of single blind testing are not proof of anything nor acceptable for publication.

    However, just like any anecdotal testimony given here between friends, any and all results are interesting and suitable for discussion.

  7. #47
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    Quote Originally Posted by rsbeck View Post
    I just think it is important to be accurate. If what you're doing is sort of single blind testing controlled solely by yourself, call it that and don't assert that you've done double blind testing.
    What would be the addition/difference that would make it double blind? Would appreciate a complete answer not just further assertions that I did it wrong .

    And, I agree, the results of single blind testing are not proof of anything nor acceptable for publication.
    Well, results of double-blind tests are not proof of anything either. Look at the test at hand in the paper. I have shown that its conclusions were not merited despite using ABX methodology. I take a good single blind test over a bad double-blind test every day of the week and twice on Sunday! If I had 100 people who could tell jitter in a blind test out of a population of 100, it would make for significant news. I am pretty sure it would make Ethan switch sides if not anything else .

    However, just like any anecdotal testimony given here between friends, any and all results are interesting and suitable for discussion.
    Damned by faint praise .

  8. #48
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    Quote Originally Posted by amirm View Post
    If I had 100 people who could tell jitter in a blind test out of a population of 100, it would make for significant news.
    Would also beg the question why (sort of) single blind rather than the more credible double blind or ABX. I think Ethan has already stated that all you need is one person to pass a DBT or ABX to back your claim and he would change his opinion.

  9. #49
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    Quote Originally Posted by amirm View Post
    Damned by faint praise .
    Not my intention. I am being sincere when I say I have enjoyed the interchange and have found the viewpoints expressed on both sides to be very interesting. Credit goes to both of you. Hopefully, you've displayed the template for more of this kind of debate.

  10. #50
    Quote Originally Posted by amirm View Post
    What would be the addition/difference that would make it double blind? Would appreciate a complete answer not just further assertions that I did it wrong .
    Double blind simply means that neither the subject, nor the people conducting the test know which sample is being tested when. You may have accomplished the same thing through your informal methodology (I've used exactly the same methodology myself, by the way), but you were both conducting the test and the subject of the test. The X is the core of the test. Randomization is typically applied through software in this kind of testing where you'l be presented with A, presented with B, then presented with X, which could be A or B, and asked to identify it.

    Your methodology may have been "blind enough," but it wasn't AB/X. By definition it can't be if you were doing this alone and going back and forth between two examples instead of randomly presenting A, then B, then X, identifying EX, and repeating. And you may have done enough trials to reach a statistically significant sample, but if you did, you have a lot more patience than I. I've done the "push the button until you forget where you are, A/B for awhile, then look" test you've described. I want to declare it audible or inaudible pretty quickly then get on to something more productive or entertaining.

    P
    Last edited by Phelonious Ponk; 08-08-2010 at 03:51 AM.

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