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R2R/multibit vs Delta-Sigma - Is There A Measurable Scientific Difference That's Audible

Discussion in 'Sound Science' started by goodyfresh, Aug 31, 2015.
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  1. KeithEmo
    First of all, yet again, you are assuming that there is some well established standard for "what quantities of jitter cannot possibly be audible".
    In fact no such standard exists.
    (Although a few tests have shown that, under certain specific conditions, relatively high levels of jitter may be inaudible.)

    Your second assertion is technically incorrect... although, yet again, you persist in describing "inaudible levels" as if such a clearly established standard actually existed.
    (When you're talking about things like jitter sidebands, which occur at audible frequencies, there is no such thing as "inaudible",
    there is only "too far below a specific noise floor to be heard".)

    Start with 100 watts of pink noise....
    Now add 1 watt of pink noise....
    You will find that the added pink noise, spread over the entire spectrum of the original noise floor, will result in an inaudible rise of a tiny fraction of a dB in the noise floor....

    Now, start with the same 100 watts of pink noise....
    And add 1 watt of a pure 440 Hz sine wave....
    You will find that the 440 Hz tone, at exactly the same level as the added pink noise, but limited to a single frequency, will result in a clearly audible tone....

    Your last one is easy.....
    Up until recently "it was well known" that "the range of frequencies audible to human beings went from about 20 Hz to about 20 kHz.....
    Until recently published test results proved that humans can actually hear as low as 10 Hz....
    (And, now, knowing that one end of the "well established range" was wrong, I'm not sure how much faith I place in the "well known limit" at the other end.)


    Note that, in the article in Science Daily, while an MRI was used initially, "All persons concerned explicitly stated that they had heard something --".

  2. castleofargh Contributor
    unless I'm misunderstanding the posts, @Dogmatrix listed some ideas but never tried to have them pass as claims or conclusions to anything. as for going further he seems to find that there are reasons to reject the feasibility of blind tests to specifically evaluate the R2R part of a DAC against the DS part while everything else is identical, and reasons to give some amount of credit to sighted feedback, but I don't remember him saying that it would or should be conclusive in any way. if I didn't completely misunderstand his posts so far, I tend to agree with the result. testing specifically the audibility of R2R vs DS is not something the amateur audiophile can do properly. we could extend the system to statistical results from having many R2R and many DS tested, and accept that for whatever reason, there may or may not be a clear trend of audible differences(like how a R2R playing 44.1kHz is in general more likely to start rolling off sooner in the upper audible range, or some other idea ). but again, it's not something the amateur audiophile can hope to test at a statistically significant level(at least I can't). the treble roll off without being tested rigorously, is likely given that many R2R DACs are NOS or offer a NOS option(often caters to the same crowd), while DS will do DS things.

    of course I already have a general opinion about the likelihood of audible differences between any DACs. that based on the many formal or informal failed blind tests and just the fact that a DAC is usually the element with the highest fidelity in a playback chain(and not by a little). so I'm tempted to simply consider that R2R vs DS is included within the group test for audibility of differences in all DACs, and draw the same conclusion. differences found are typically small, most of the time inaudible for the average human.

    if we rely on testimonies from uncontrolled feelings about DACs, there seems to be a trend of subjective preference for R2R. 2 issues here for me:
    1/ it's one of those situations where people can tell us how different it is in great details with confidence, but somehow are very bad at demonstrating that they're actually hearing any difference at all. which could very much suggest shared preconceptions about the differences to be heard. I've talked to maybe 25 people over many years, who really tried to blind test DACs properly(some including a R2R DAC) and could pass for whatever reason not clearly defined by their experiment(as those tests try to demonstrate audibility, not determine the cause). and the very vast majority of the remaining testimonies in subjective favor of R2R, seem to have been participating in a contest on how not to test anything.
    2/ DS DACs are everywhere, they have completely taken over a market. so it should be factored in that users vocal about that R2R preference,are similarly to those being vocal about how nice vinyl is, drops in the ocean.
  3. gregorio
    1. Of course it does! For example, jitter artefacts at say -130dBFS are inaudible and even some cheap DACs achieve such a figure. The rest of your post is essentially circular logic based on this initial false assertion, false analogies and false statements.

    2. Why? What has 100 watts of pink noise got to do with jitter artefacts well below -100dBFS?
    2a. Thanks for clearing that up, you're saying that your DACs produce 100watts of pure tone jitter artefacts are you? That's easily the worst DAC ever made, by orders of magnitude!

    3. What recently published tests, can you link to them? Obviously the ones you linked don't count because they don't conclude "humans can actually hear 10Hz", sense/perceive yes but hear no.
    3a. Firstly, we don't know that "one end of the well established range was wrong" and even if it is, it's pure fallacy to assume the other end is! Secondly, that's NOT even audio science, it's psychoacoustics. So far then, your "significant percentage" is exactly 0% and that's the only question I asked you thought you might stand a chance of favourably answering, don't you think that's funny?!! And lastly, fortunately this isn't the "What KeithEmo has faith in" forum ... Some reliable supporting evidence or it's marketing BS!

    Talk about circular logic, thanks for the great examples (again)! Why do you always follow the same fallacious tactics, you think maybe sooner or later we'll fall for it?

  4. KeithEmo
    I'm sorry..... which jitter artifacts, at which frequencies, and in which proportions, are inaudible below 130 dB?
    (And could you please reference the specific test that showed this conclusively.)

    Please note that I am not specifically asserting the opposite to be true...
    I'm merely pointing out that you are stating an assumption as if it were a confirmed fact.
    (Since I haven't tested it, or seen the results of such a test, I'll admit that I don't actually know one way or the other.)

    I should also point out that you seem to have some confusion about the difference between relative levels and absolute levels.
    (For example, I suspect that artifacts that are 130 dB below 1 megawatt would be quite audible - if played on my office system.
    Or are you referring to artifacts that are 130 dB below some specific signal level?)

    Last edited: Aug 27, 2019
  5. bfreedma

    This must be some form of audio reproduction or music style of which I am not aware.

    More seriously, anyone can play the game of contriving an example that isn't relevant in the real world, but what is it accomplishing in terms of this discussion?
    Last edited: Aug 27, 2019
  6. KeithEmo
    I suspect you are correct - and that, if there are inherent differences, when both are implemented properly, they are quite small.

    However, there is one important consideration, vis-a-vis audiophiles with limited resources to do comparisons.... and marketing.

    R2R DACs are a sort of niche product.
    Compared to a D-S DAC that delivers similar technical performance, an R2R DAC is likely to cost more, and to be sold in smaller volume.
    (You will also find that, as a group, R2R DACs are more often represented as "audiophile products".)

    The upshot of all this is that there is a stronger motivation for a company or designer to DELIBERATELY design their R2R DAC to introduce some sort of coloration.
    In colloquial terms, they want to make sure that their product sounds audibly different as a way to justify both its higher cost and its status as an "audiophile product".
    Or, to phrase that another way, they are likely to place a higher value on "a unique sonic signature", rather than on a neutral or accurate sonic signature.
    This makes it more likely that an R2R DAC, and especially an NOS R2R DAC, will sound "distinctly different" from its competitors....
    (They are trusting that, specifications aside, if their product sounds "unique", they will be able to convince some potential customers that it sounds better.)
    (And it makes it doubly important that you make a careful effort to distinguish "different" from "better".)

  7. castleofargh Contributor
    that's an argument in favor of possible audible differences that I find most convincing. I'd still like to see more controlled tests demonstrating it, because that's how I roll. but at least it's not a situation where we have to make up new laws of physics or discover a new listening organs in the human body to try and justify claims of obvious differences.
  8. KeithEmo
    Jitter is simply any variation in clock speed....
    When the clock speed varies, that speed variation modulates the audio signal itself, resulting in distortion.
    You can then measure the spectra of the distortion that results - which is what you often see expressed graphically.

    However, as with any other form of modulation, the frequency and waveform of the modulating signal, and of the music signal, together determine the result.
    In this case, it's very difficult to characterize "what's more relevant", because jitter can occur at virtually any frequency (between a fraction of 1 Hz and hundreds of kHz).
    And jitter can also occur with an infinite variety of weveforms and random distributions.
    Each individual device or circuit is going to have different amounts of different types of jitter.
    And each combination will produce different sidebands, both inside and outside the audio band, and in different proportions.
    (I'm sure that, with enough data, you could characterize which sorts are most common, and in what quantities.)

  9. bigshot
    "Since I haven't tested it, or seen the results of such a test, I'll admit that I don't actually know one way or the other."

    That should be your motto. Of course it's good that you resist performing controlled tests. That helps you maintain your perfect record.
  10. KeithEmo
    I agree....

    I'd like to see a few more tests...
    And a little less justification about why we know so much that there's no reason to bother testing things...

    "Obvious" is and always will be a matter of personal opinion....
    I'm told that there are "obvious" differences between the sound of a Stradivarius and a $1000 Sears violin....
    However, to be honest, I'm pretty sure I couldn't tell them apart....
    But that DOES NOT mean that the differences don't exist....
    Or that the people who insist they do hear them are imagining them....
    (Although it's also quite possible that some of them actually are...)

  11. gregorio
    1. All jitter artefacts at any frequency and in fact anything at all at -130dBFS is inaudible. If we take a loud peak playback level, say 100dBSPL, then 130dB below that is -30dBSPL, how are you even going to reproduce that, let alone hear it?
    1a. I don't have a specific test showing that -30dBSPL is inaudible. I also don't have a specific test showing that -10,000dBSPL is inaudible, so that means they are audible! Well, I would never have believed it, I'll call CERN tomorrow and tell them to switch off the LHC, they don't need it, I can easily hear Higgs Bosons!!

    2. You have a 1 megawatt system in your office do you? How big is your office and how many kilometers do you sit away from the system?

    You respond to the accusation of nonsense with more nonsense, how circular is that and what does that make you?

    bfreedma likes this.
  12. bfreedma
    I think you missed the part of your post that I highlighted and was responding to - where does the item below exist in audio reproduction of musical form?:

    "(For example, I suspect that artifacts that are 130 dB below 1 megawatt would be quite audible - if played on my office system."
  13. gregorio
    The really ridiculous part of it is that even if such a system existed, you had one in your office and played back artefacts that were potentially audible, say around 50dBSPL (roughly the same as the noise floor in an average office) then peak level would be 130dBSPL higher than 50dBSPL (180dBSPL) and you still wouldn't be able to hear the artefacts, unless you can hear them while a patient in an intensive care ward or a morgue!

    His flying pigs argument was less ridiculous, as hard as that is to imagine! :)

    Last edited: Aug 27, 2019
    SilentNote and sonitus mirus like this.
  14. bfreedma

    Perhaps the two analogies are related. I can imagine that if such a system existed, it might shoot pigs across the sky from the shock wave.

    Was there a swine population on Krakatoa on 8/27/1883? Or in Tunguska on 6/30/1908?
    gregorio likes this.
  15. gregorio
    Not sure but I'm pretty sure there wasn't on 8/28/1883 and 7/01/1908 respectively :)

    bfreedma likes this.
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