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Thoughts on a bunch of DACs (and why delta-sigma kinda sucks, just to get you to think about stuff)

Discussion in 'Dedicated Source Components' started by purrin, Dec 5, 2013.
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  1. immersifi
    Again, I am not discounting opinions or attempting to denigrate them; everyone's opinion and preference counts (or should). I am however attempting to make a distinction between the results of well-designed tests conducted in an controlled fashion and opinion. Again, when differences are clear (and I'll concede that's a relative term) then yes, such structured tests are overkill.
    I can say that, having worked (since 1990) in signal processing, NVH, and sound quality, double-blind tests are what is used industry-wide (and not just in automotive, but pretty much everywhere) to perform anything from simple rank-order of preference (product "A" against "B", "C", "D" and so on) down to regression analyses to better understand which psychoacoustic metrics best correlate with listener preference of the sounds evaluated. This is done for everything from power tools, to door closures, to hair dryers, leaf-blowers, lawn mowers...pretty much everything. Sometimes the answer is pretty immediate and clear, and other times, it's inconclusive.
    One other thing that's done in industry that's never really done in these threads (not specifically headfi.org but others as well) is that in product development circles, the sounds that are recorded for evaluation by jurors are played back at 1:1 loudness levels. Let that sink in for a minute... in other words, if (for example) a dishwasher produces 57.5 dB(L), then that sound and others to be presented are presented at their correct levels in the headphones (in this example, the dishwasher sound, when played back in the headphones will produce 57.5 dB(L) SPL).
    This really does matter, because of the anything-but-linear nature of the Human hearing mechanism. So, by ensuring that sounds are played back at a 1:1 loudness level (whether in sone or decibel) a fair comparison between sounds can be made. Otherwise, if left uncontrolled, by raising the gain, you may hear certain things that would otherwise be masked when the sound is generated by (in this case) the dishwasher. Conversely, if one were to conduct such tests at a lower-than-actual playback level, there is a reasonable chance that one would miss certain attributes of the sound. I think it's clear that after spending time (and costs) in setting up the test etc.to have the validity compromised by evaluating the products at levels other than their actual levels could be 'problematic'.
    This should sort of make sense to anyone reading this even if they are not acquainted with the Human hearing mechanism's workings. That is, who among us hasn't noticed that what we perceive as well as emote can be dramatically affected by the level at which we choose to evaluate the sound (or song), or even simply listen to a track for pure enjoyment? This is a pretty important aspect of hearing and one that seems to be seldom controlled in most of the listening evaluations most often discussed on the web.
    The problem with calibrating the levels of music is, of course, the recordings are seldom if ever level-calibrated (it is possible to do...), so there is a lot of latitude resulting in terms of what levels can (and will) be chosen when attempting to make an unbiased comparison between sounds / products. Mind you, if the Human hearing mechanism were linear (and by linear I do not mean 'flat') then the level at which sounds were presented would matter not, but this is not the case.
    It's for this reason that juried sound evaluation software packages allow a loop calibration to be performed thereby ensuring 1:1 playback of actual sound levels. But...don't take my word for it - check the Society of Automotive Engineers (S.A.E.) database as well as those of the Institute of The Institute of Noise Control Engineering (I.N.C.E.) as well as the Acoustical Society of America (A.S.A.) for published works on juried testing (basically, similar to ABX, but with a few more options). If you are interested in knowing more about listening tests, you can web-search for 'juried tests' and "Bradley-Terry" as a start, but if you likewise search the names "Otto", "Lake", "Blommer", "Crewe", and "Cerrato" you will find many published works on double-blind juries testing and the results. Interesting stuff.
    arnaud likes this.
  2. Stillhart
    FYI, discussions on double blind testing outside of the sound science forum is a great way to get the thread locked and some bans handed out.  Second only to discussing cables.  Not threatening, just warning...Amos is not a gentle mod.
  3. immersifi
    Hmmm...I'm not sure why I should be banned for discussing something that's related to the subject. In no way did I denigrate anyone or their positions or opinions, nor did I say anything untoward about any or all of the products mentioned. In fact, if you look at my previous posts, I actually asked the question about whether the assertions made were opinion, or based on more rigorous methodologies (and I even thanked one Member for having clarified the issue).
    Having said that, I hope that what I have written does not get me 'banned'. I like the discussions here, and so far, I've managed to meet some very cool people.
    Mark (immersifi)
  4. Stillhart
    No judgement implied, man.  I'm just letting you know how Amos works.
  5. Ableza
    If people get banned for off topic discussion then half the participants in the Schiit threads should be gone. Including me.
  6. Stillhart
    I named two very specific topics, not all off-topic discussion.
  7. purrin
    I doubt a guy who wears a T-shirt "D-S, when music doesn't matter" would subject any of us to an "upgrade" from D-S to D-S. The Bifrost form-factor seems awfully limited on real-estate though.
    Hahaha. One thing I noticed when I popped the hood for the Gen 2 USB upgrade was the amount of space available.
    Some of the early stuff was done blind, but informally. Later, we shared notes. The R2R revelations and rankings are mostly my own, although specific attributes are agreed upon with the same set of people I share notes with.
    In the end, it's all subjective opinions. Just crap outta my ass, confirmation bias, placebo, et. al. Take it as you will. I take audio seriously, but I don't take myself seriously.
    I conducted a formal blind test of two amps level matched to +/- 0.1db with a switch box. Never again will I do such a thing. Never again. Easier to talk about than to do.
  8. mikek200
  9. Armaegis
    I wonder if there's enough space to fit in some transformers for a balanced output...
  10. wink
    Or, a switch on the front.
    Or, perhaps even, a sensor for a remote control...........   [​IMG]
  11. Sapientiam
    Listening isn't as black and white as being either 'based solely on opinion' or 'based on rigorous methodology'. There is middle ground between those two poles - that's falsifiable descriptions of what we hear. Smell is equally a purely subjective perception but qualitative descriptions in that sensory domain have turned out to be useful to developers of scents. Luca Turin has done some excellent work there and you can read about that in his and Chandler Burr's books.
  12. Stillhart
    Random question:  I've been listening to the Adcom with a coax cable from the Gustard U12.  On a whim, I connected the AES/EBU connector (3-pin XLR) and swapped to that.  I could swear it opened up the congestion and SS just a tad.  Is that possible?  I might have to have my wife flip the switch for me so I don't know which is which...
  13. purrin
    Audio is like food to me. Xiaolongbao at Din Tai Fung at the Glendale, California location is not as good as the xiaolongbao at the Din Tai Fung at the Xinyi Taipei location. I don't need to take a double-blind and/or ABX test to know this or tell other people this. If anyone has a problem with my assertion, they are free to conduct their own double-blind ABX taste test of the xiaolongbao at these locations.
    jsgraha and Articnoise like this.
  14. purrin
    AES3 sounded better from the OR5 into the Gen V than SPDIF. Further improvement: very short run of a twisted pair in CAT5 (effectively same characteristic impedance of AES cable). Good time to learn how to solder if you don't already know how. Can save lots of money, or have you end up melting a lot of things.
  15. Stillhart
    Yeah, I've made my own cables and put together a Project Solstice.  Are you suggesting I use CAT5 cable into 3-pin XLR for AES3 connection?
    BTW, I'm pretty sure at this point that it opened the soundstage and lowered the noise floor a bit.  Not much, but enough to not go back to coax.
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