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Low-Jitter USB: Dan Lavry, Michael Goodman, Adaptive, Asynchronous

Discussion in 'Computer Audio' started by jude, May 20, 2010.
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  1. nick_charles Contributor


    A 4hz sampling deviation in a 44,100 system is what 0.01 % , this is below the limits of human pitch difference discrimination at any frequency, relax ! 
  2. leeperry
    (44105/44100)*440=440.05 Hz, it's an out of tune A
  3. jcx


    yeah digital really sux - maybe you just go listen to Miles' "Kind of Blue"...
  4. leeperry

    humm? m2tech boast about much tighter sample rates...but I can't justify the $150 for their hiface, besides their drivers seem quite buggy and they're working on their next interface already. bang for bucks looks huge on the Monitor 01USD, I suppose I can live w/ slightly out of tune music [​IMG]
  5. mgoodman
    @ shamu144:
    Theoretically, everything should just work and the bus should be always on time :) The devil, as usual is in the details.
    In practice, Asynchronous does not offer a significantly easier or cheaper clean up experience. Our DAC is cheaper than some asynch implementations and yet is sounds better in many respects, so it's not about component cost.
    A lot depends on the design of the power supplies, PCB layout, the clocks themselves (adaptive and asynchronous both rely on the quality of the locally generated clock.) Clean up of the digital signal almost becomes a moot point. It's actually not difficult to do. Anyone can design digital circuits, because they are largely insensitive to variability in power supplies, jitter, etc. Getting the analog right however (what happens after the D/A converter), is the hardest part, if you want my opinion. That's where the engineering chops are really tested. The analog part is sensitive to everything and so the care really goes there. Of course, it's also more difficult to discuss, so the "easy to sell" argument is the digital one :)

    Yes, but when it comes to jitter, isn't async supposed to be theorically easier to clean and implement than adaptive, and therefore potentially yield better results at lower costs.
  6. xnor
    Why should async be easier to implement? 
  7. nick_charles Contributor


    Wthy not use a signal generator to create 440.00 and a 440.05 sine waves and try DBT'ing them, I just tried this 
  8. regal

    Do you realize there are people who can identify 1% speed/note change and there are some that are tone deaf?     You would have to run the test on a large pool of people to have any meaning.

  9. thuantran
    Pretty fun to do, got 77.8% through my "so so" speakers I wonder if that's good or bad compared to ppl here. I have zero training regarding music, only like to listen to it :D.
  10. nick_charles Contributor


    Well, the thresholds for pitch difference discrimination have already been established by existing psychophysics research and 1% is several orders of magnitude worse than the deviation Leeperry was worried about, leeperry talked about 440.00 vs 440.05
  11. leeperry
    Good idea, I will run the test! Anyway, having more thoughts I came to the conclusion that analog audio wouldn't be any better...tapes/vynils, you can rest assured that they don't play your music at their very spot-on speed.
    Besides noone pointed out that my computing was flawed because the inaccuracy "window" gets higher the more you increase the sample rate(that's what m2tech are saying at the end of that PDF anyway)...so basically it's quite a big of a deal for 176.4/192kHz where the PLL inaccuracy will be quite huge but DBT'ing a 44.1kHz song resampled to 44.105 seems tough. I will try this too [​IMG]
  12. Mad Max
  13. bigshot
    Jitter is a hoodoo. The reason vinyl sounds better is because it was engineered better. Studios used calibrated speakers to mix with and generation loss was scrupulously avoided. There is nothing wrong with rebook as a format. The reason digital sounds bad is all the sloppiness that the flexibility of digital encourages... Fake reverbs, manufactured soundstage, bizarre miming, filters, etc.

    Want proof? Take your best sounding vinyl record and digitize it. Balance the line level between the LP and the digital copy of the LP and do an a/b comparison. I've done this. No difference.
  14. Phelonious Ponk


    More or less. Jitter is certainly real, and you may even be able to hear abnormally high amounts of it, through very quiet gear, over reference headphones, at high volume levels, if you're listening for jitter instead of music. Enjoy that. And there are plenty of great redbook CDs out there, you just have to avoid modern pop music and classic rock remasters. Jazz, folk, blues, acoustic, alt country...plenty of this stuff is being recorded and mastered well. Even now. Even digitally. The digital haters are blaming the hammer for a bunch of idiots who like set the nails so deep they split the wood.
  15. JeffL
    Cables, speaker spikes, balanced power, and now jitter.
    What nonsense will they think of next?  [​IMG]
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