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USB cable and Sound Quality

Discussion in 'Sound Science' started by rudybagel, Jul 4, 2012.
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  1. bigshot
    I don't think it's at all productive to talk about what causes jitter and how it works in great technical detail if you don't put that into real world perspective... Is it something that someone is likely to have happening in their own equipment? If so, is it at all audible?
     
    Every time I get drawn down the jitter rabbit hole, it's always the same... reams and reams of technical double speak and then after my brain hurts from trying to absorb it, then the person says... "But of course it really isn't an issue because it's inaudible."
     
    If that's the case, we should just cut to the chase and spare everyone the technical mumbo jumbo.
     
  2. mikeaj
    PLLs, phase tracking, etc. are ostensibly on the periphery of what's supposed to be my expertise. Consider it partly professional interest. Also, it's bad form to be knowingly perpetuating technical errors.
     
    As for improving sound quality, I doubt it. Regardless of even what the reality is, that discussion's pretty much going nowhere unless somebody can cite a decent listening test that confirms some level of audibility different than what's been established, and I think we already got to that point somewhere in the last 50 pages... probably multiple times.
     
  3. 00940
    Quote:
     
    You need to qualify your questions... what is happening ? Measurable jitter in between 500ps and 3-4ns ? Of course. It's a matter of engineering.
     
    Quote:
     
    Probably not. It's a matter of psycho-acoustics.
     
    Quote:
     
    The difference is that the person who concludes by saying it's inaudible has grounds to say so (isn't it the science forum, where opinions must be substantiated ?). If you want to cut the chase, two tips:
     
    1/ ask the technical minded persons what levels of jitter are actually involved and then ask for proof of audibility (in the realm of psycho-acoustics).
    2/ avoid getting drawn in the technical aspect of it, There's no "double speak". It's just complicated. Best way to proceed is to avoid open (and false) statements such as "digital is perfect, all that matters are 0 and 1". This kind of things just begs to be corrected by a lot of technical mumbo jumbo.
     
  4. bigshot
    Who cares if jitter exists if it isn't audible? Thresholds of perception are a part of science too. Speaking about something in theory without putting all those numbers and specs into perspective is deceptive. Human specs / electronic specs... they are related.

    We're all here to get stereo systems that sound good to us, right? We're trying to help people, not just listen to ourselves speak.

    Obfuscation by inundating the listener in technical minutia is what snake oil salesmen do. Sound Science people shouldn't add to that confusion. Our purpose should be to explain and put into context.
     
  5. nick_charles Contributor
    Quote:
     
    From much searching including the AES library to date there have been 3 research papers which have more or less seriously attempted to empirically determine the limits of audibility. One is a 1970s BBC paper, one is from two dudes at Dolby labs (Benjamin and Gannon)  (1998) and the last is from NHK (Japanese Public Broadcaster)  in 2005. The types and levels differed, what all three implicitly agreed on was that achieving an audible level required pathologically bad equipment. The Dolby labs paper (the most conservative) put audibility for a single tone at about 10ns signal-correlated jitter rising to over 300ns with some musical samples with a minimum of 30ns for musical samples
     
     
     
     
    I've petitioned many of those that might be called jitter-worriers to provide good counter evidence for the lower thresholds they claim are audible and to date have not had one credible piece of evidence, thus I no longer consider jitter to be an issue.

     
  6. 00940
    @Bigshot: I very much doubt this particular thread is really helping anyone... But it's the cynical in me speaking.
     
    A few pages back, you wanted explanations. Need I remind you ?
     
    Quote:
     
    Sorry, but you should make up your mind about what you want. If you don't understand the technical aspects and don't want to spend time to learn, that's all fine. But don't comment on them. Because you are the one confusing things by doing so.
     
    In other terms, what's the most confusing thing to tell to someone reading jitter oriented marketing litterature: "there's no jitter; here are plenty of (wrong) reasons why" or "there might be jitter indeed, we know where it comes from but the levels involved here are below audibility ?"
     
     
    @nick_charles: that's all fine with me (and we've discussed those papers a lot already in the past). Let's keep 10ns to be on the safe side and have a nice easy value to remember. As said in my post above, half-decent adaptive receivers give at worst about 3ns of jitter (for pcm2702 and pcm2902, pcm2707 are in between 500ps and 1ns) and we agree that it's probably not audible.
     
  7. 00940
    @Bigshot: I very much doubt this particular thread is really helping anyone... But it's the cynical in me speaking.
     
    A few pages back, you wanted explanations. Need I remind you ?
     
    Quote:
     
    Sorry, but you should make up your mind about what you want. If you don't understand the technical aspects and don't want to spend time to learn, that's all fine. But don't comment on them. Because you are the one confusing things by doing so.
     
    In other terms, what's the most confusing thing to tell to someone reading jitter oriented marketing litterature: "there's no jitter; here are plenty of (wrong) reasons why" or "there might be jitter indeed, we know where it comes from but the levels involved here are below audibility ?"
     
     
    @nick_charles: that's all fine with me (and we've discussed those papers a lot already in the past). Let's keep 10ns to be on the safe side and have a nice easy value to remember. As said in my post above, half-decent adaptive receivers give at worst about 3ns of jitter (for pcm2702 and pcm2902, pcm2707 are in between 500ps and 1ns) and we agree that it's probably not audible.
     
  8. bigshot
    I would think the simplest and most accurate answer to the question would be, "It can't be heard so it really isn't worth worrying about."
     
    Perhaps people are here for reasons different than I am. I'm looking for the Sound Science forum to make sense of the technical aspects of sound reproduction for the purpose of improving the way my music sounds when I listen to my stereo system. This thread just confused me and led me astray into thoughts of angels dancing on heads of pins.
     
    I know a little bit about how digital audio works. But I've never owned an external DAC, only AV receivers and standalone players. I did the research into jitter as it applies to those particular applications and determined it was well below the audible level. No need to think any further about it. Bigger fish to fry. I come to this thread and people are talking about "massive" problems and a whole bunch of technical cut and paste and I don't think it takes a huge leap to assume that if people are talking about it with such vehemence, it must be a serious problem.
     
    It's actually my mistake. I should have just ignored all that stuff and gone with my gut and posted the simplest and most accurate answer. Honestly, every time I look into jitter it just makes me mad that anyone is worrying about it at all. Jitter is a hoodoo.
     
  9. Rawrbington
    Not trying to derail this discussion, as I love it.  But I have a question about my current USB cable and my USB dac.
    I have an old fubar ii usb dac doing its duty in my bedroom rig.  The problem is, I get occaisionaly, but sometimes fairly frequent dropping out and what sounds like skipping.  Sometimes it won't happen for 30 minutes, other times it happens sever times in a 2 minutes period.
    could this be my cable?  Im using a random printer cable with the ferrite core thing.  It's of unknown age(could be 10+ years old).
    Now,  I'm on one clear side of this debate, BUT in this situation, could it be my cable, or (most probably) my usb ports/mobo?
     
  10. liamstrain
    Much more likely to be computer issues. Shared resources, or other. Many people have noticed issues with their graphics card stealing memory and causing usb audio issues (especially when re-painting the screen during web browsing, for instance). Check out the computer audio threads for some specific troubleshooting suggestions. 
     
    Unless the cable is quite long (over 3m) it is the least likely culprit IMO. 
     
  11. White Lotus
  12. dvw
    Quote:
    I had a similar problem. It was a driver issue. Install new drivers and everything's running.
     
  13. Greenleaf7
    Quote: I'm pretty sure this cable will 'open up the soundstage' and remove the 'veil'.
     
    Don't forget to choose one of these http://www.musicdirect.com/c-618-powerline-conditioners.aspx
    Remember, your audio rig is never complete without a high end power conditioner.
     
    You'll also need an audiophile grade wall plug to get the best out of your system.
    http://www.musicdirect.com/p-7398-oyaide-carbon-fiber-wall-plate-without-outlet.aspx
     
    And to top it off, you'll need to demagnatize your equipment from time to time.
    http://www.furutech.com/2013/02/02/1792/
     
  14. xnor
    @rawrbington: check your PC's DPC latency with something like LatencyMon or DPC Latency Checker.
     
    If that is fine try other USB ports.
     
  15. Rawrbington
    im pretty sure you guys are right.  i'll check it out and see what happens.  its an older system,  core 2 quad built in 2008.  and it does seem more prevalent when im doing other things (multitasking). 
    thanks for the info
     
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