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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. drez

    Funny I feel that I can hear more music from my current SD DAC than my previous, more expensive R2R DAC from the same manufacturer. I dont count soft, murky, rolled and veiled as contribtuing to my enjoyment of music. Yes the saving in cost was passed onto me. Yggy is the exception to my admittedly limited experience in that it musically surpasses dacs in its price range.
     
  2. BassDigger
     
    As I understand it, D-S implementations are much cheaper. If this meant that all D-S dacs are equally cheap, fairplay. But my point is that they're sold at a similar price, despite being significantly cheaper to produce.
     
    I'll try not to be so black or white and all-encompassing, in my statements; some, like yourself, do seem to prefer D-S. (Although, I don't recognise any of your adjectives when it comes to describing the 'sound' of an R-2R dac.)
     
    Each to their own, although musical preference probably has some influence.
     
  3. KeithEmo
     
    Agreed... sort of...  although the type of oversampling used in A/D converters doesn't have the same issues as D-S D/A converters anyway. (When you use oversampling in a DAC, you're creating new interpolated samples, which then require significant filtering; when you use oversampling to digitize something analog, you are taking actual samples at a higher sample rate, then mathematically reducing them later. In short, there's no "artificial made up information" involved - and so no "guessing" - just initially recording more information than necessary, then eliminating the excess later. In an engineering sense, it's much easier, and more well defined. Therefore, the problems with oversampling DACs aren't present in oversampling A/C converters.)
     
    However, it doesn't really matter what equipment a certain studio uses, unless they happen to produce recordings by the artist I want to listen to. If you happen to like Beethoven, you have your choice of hundreds, or even thousands, of recordings of it - by various orchestras, with various conductors, and from different production companies. (Wouldn't it suck if the best and most wonderful version of that song that Ella ever sang was recorded by some cheesy studio on crappy equipment?) My favorite group plays electric guitars, and electric keyboards, and the vocalist always seems to be glued to a microphone. They even mike the drums.The mixing engineer at the recording studio they use seems to think that you there's no real purpose for Volume and Compression settings lower than 10, and the few times I've heard them "live", the PA system at the club they were playing at was even worse. (Nothing bugs me more than "discovering" some new music store, who records all their own stuff "direct to digital", using the best equipment currently available - only to find that they have exactly NOTHING for sale that I actually want to listen to. The great thing about MoFi in the old days was that they actually re-mastered recordings that I actually wanted - and cared about.)
     
    (If I was actually a fan of Louis Armstrong, or Ella Fitzgerald, my biggest regret would be that I can't get a "proper" copy of either on a full quality 24/192 digital format - because, since they weren't originally recorded digitally, all I can get today is a copy made from an analog tape or vinyl master....   )
     
    I guess the point I'm trying to make is that most of us have little choice of what equipment was used to master what we listen to, because we're stuck with whatever equipment the studio our group chose to produce their album used. Therefore, I'm more concerned that my own playback equipment does the best job possible to reproduce "most Red Book CDs, and now digital download files", and less concerned that it do an excellent job with one or two specific ones. (And this is why I take the "obverse" viewpoint to some people about things like the ringing introduced by digital filters. I'll concede that all oversampling DACs have some ringing, but the filters used to produce virtually all CDs also have some ringing, and so do phono cartridges for that matter, so I'm more concerned with whether the DAC ADDS any ringing or other artifacts that are audible above and beyond the flaws that are already present in the recordings I have, and less concerned whether it can render that one "perfect" Ella Fitzgerald recording - which I'm not interested in listening to anyway - to sound perfectly natural.
     
    And, as for things like "natural ambiance and decay" - which were mentioned as being critical in that article quoted about MFSL..... well, I'm pretty sure that, on Within Temptation's latest album (they're MY favorite group), any ambience that was there probably came from a plugin, added by the mixing engineer, after the recording engineer removed any real ambiance that was actually picked up with coarse-grit sandpaper.
     
    Therefore, I'm very interested in having my equipment deliver "his artistic vision" (I want to hear what he wanted me to hear), but "natural" doesn't really come into that discussion... at least not as something distinct from "reproducing whatever is on the recording as accurately as possible". And, in all fairness, unless anyone here was actually alive when it was recorded, and has an awfully good memory, nobody here knows whether that Louis Armstrong recording sounds natural either (as in "what it actually sounded like when they played it live"); the best you can do is do make a judgment call about whether you think it sounds a lot like what you imagine it sounded like in that studio. (You can assume that it sounded a lot like what a well produced concert sounds like - to you - in a "good" modern concert hall.... but that is just an assumption. Tastes, including "what a concert hall should sound like" change, so perhaps it really sounded very different back then.)
     
    rovopio likes this.
  4. KeithEmo
     
    Your first statement is technically true today - but it really does deserve clarification because, although accurate, it gives a false impression of the economies involved. It's not that, given a certain set of requirements, a D-S DAC chip costs $2, while a R2R chip costs $5. It's more like the fact that, if you want a ride to the airport, a ride in a car is a LOT cheaper than a ride in a horse-drawn carriage - because there are so few horse carriages available nowadays that you will have to make expensive special arrangements to use one. If you want to design an audio DAC, using a "commercial off-the-shelf 24 bit audio DAC chip", I don't think you can buy an R2R one at ANY price. Yggdrasil uses DAC chips that are NOT intended for audio, which not only cost more, but require the designer to design all sorts of extra circuitry (to duplicate functionality that is already present in an "audio DAC chip").
     
    So, in fact, it's NOT that: "they save a few bucks by using the cheaper D-S chip".
    It's more like: "if you don't want to use the standard parts everyone else uses, then you have to do it all from scratch".
    (And "hand-made custom-designed" products always cost more - whether they're actually better or not.)
     
    Imagine saying: "I really hate Microsoft Windows, but I also hate Apple software; I think I'll hire someone to design me a computer from scratch" and you're closer to the reality.
    (And even the US military has gotten away from that extravagance wherever possible.)
     
    16 bits is pretty much the dividing line between "it's a little more expensive to do it in R2R" and "it's REALLY hard, and expensive, to do it in R2R, if it can be done as well at all".
     
    The problem with ALL adjectives is that they are not only imprecise, but they tend to mean different things to different people.
     
    And the problem I personally have with every discussion I've heard lately about "D-S vs R2R DACs" is that they are all based on someone's adjectives.
    Oversampling DACs always alter the transient characteristics of the signal - at least slightly; it's an unavoidable "side effect" of the digital oversampling filter.
    However, I am not aware of any specific technical difference in the performance of oversampling D-S and R2R DACs.
    Yes, SOME D-S DACs, with SPECIFIC circuit designs, may produce a modulated noise floor, which MAY be audible under some conditions.
    And, yes, some R2R DACs have issues with glitching at the transitions, which can also be audible.
    (You can't avoid oversampling with a D-S DAC, while an R2R DAC can use oversampling or not, but we seem to be assuming that isn't the issue.)
     
    My point there is that I can show you the ringing of an oversampling filter in oscilloscope photos - and we can compare pix from different DACs.
    While I have yet to see a single photo purporting to show how the output of a D-S DAC and an OVERSAMPLING R2R DAC with a similar digital filter are different.
    I want to actually see a picture showing me a D-S DAC that is exhibiting "mistracking" or whose noise floor is "obviously modulated"
    (while a picture of that same signal, reproduced by an oversampling R2R DAC, obviously lacks that flaw).
     
    Instead, what I actually see is a lot of technical discussion about highly technical flaws in the way in which D-S works.....
    Followed by a bunch of subjective opinions about how specific R2R DACs sound better than other D-S DACs to certain people.
    Usually followed by some vague assumption that the two must be related.
    But what's missing is any specific correlation.
     
    If the "modulation of the noise floor by D-S DACs" is really audible, then it should be easy to show that all those purportedly great sounding R2R DACs actually have a noise floor that looks and measures differently than the noise floor on all those purportedly bad sounding equivalent D-S DACs. However, if, when we look and take measurements, we find that the theoretical flaw is undetectable in practical terms, then perhaps a lot of people are barking up the wrong trees. Assuming that the assumptions are correct, the it shouldn't be that difficult to actually take the measurements, and show the photos.
     
  5. BassDigger
    Aah-ah-aaah. There you go again; missing (avoiding) the point. Yeah, sure, r2r dac prices are prohibitive today; nobody makes r2r audio chips, anymore.
     
    $2 vs $5?!? Is that the real cost difference between the two? I think that by the time you've constructed suitable circuitry, around the chip, the price difference is greater than $3; maybe more like $200 vs $500. And that was back when r2r was the norm and the chips were widely available.
     
    Let's remember that bitstream began life, like most technology, as a solution to a problem; it was used to add an extra couple of bits to a 14bit r2r dac. Am I right? 
     
    What was the driving force, the motivation, to adopt this method to convert all the bits of 16 bit audio? Was it superior performance or reduced manufacturing costs?
     
    As an r2r lover; someone who feels like they know a bit of a secret, I wonder if I should be bothering to discuss this. After all, prices of some vintage dacs are getting silly these days. But, if r2r really is better, don't we, as music lovers, need to spread the word and generate some appreciation, understanding and ultimately demand for whatever is the best conversion technology?
     
  6. jacal01
    What we have is auditory feedback from competent reviewers who feel that they can discern a distinct improvement in musical fidelity in implemented R2R DAC over D-S DAC equipment in their system. Competency considerations notwithstanding, that includes me.
     
    Argo Duck likes this.
  7. rkt31
    another Hugo vs yggy. interestingly the reviewer found Hugo smoother.
     
  8. rkt31
    here is the link https://www.avforums.com/threads/chord-hugo-tt.1962917/
     
  9. ciphercomplete
     
    Considering that I have compared two lesser R2R dacs (Audio GD DAC19 - the old version, Audio GD ref 5) to the likes of the Onix XCD 50, Tentlabs CD player, and the BMC BDCD 1.1 - all extremely well regarded - and did not once feel the need to purchase those players says that at least some of the magic is indeed attributable to R2R.  Funny thing, the guy that owned both the Onix and Tentlabs now uses the Onix as just a transport to feed a Audio GD Master 7. 
     
  10. KeithEmo
     
    First off, I'm a little bit confused by the way you phrased that. There's no such thing as magic. The job of a DAC is to convert a digital audio signal into an analog audio signal as accurately as possible (some audiophiles prefer to substitute to "so it sounds good to me" for "as accurately as possible" in that sentence). However, my point is that, assuming that those Audio GD DACs work well, and sound good to you, then I see no reason to expect that others would be better, or to be surprised that they aren't. (I've heard $30,000 DACs that, at least to me, don't sound any better than the $500 one I've got on my desk - and I don't find that especially surprising at all. Therefore, I don't find the fact that you didn't find certain other "well regarded" products to be superior to be especially meaningful. If the Audio R2R DACs you're talking about work well, then why would you expect anything else to sound better?)
     
    I have several Audio GD DACs - none of which happen to be R2R - yet they do sound rather different from each other. In fact, AudioGD is sort of known for "voicing" of their various products. (They used to sell several "discrete op-amps"; each had a cute name, like "Earth" and "Moon", and each was claimed to sound different from the others. Even their analog headphone amps sound different from each other.) In fact, their general product philosophy seems to be to offer a wide variety or products, so as to have "one for every taste" (they also sell R2R DACs, and Sabre DACs, and units with Wolfson DACs). 
     
    My point, however, in the context of THIS discussion, is that, since Audio GD products in general are known for "being voiced", rather than "being as neutral as possible", I wouldn't be inclined to generalize from their R2R DACs to "all R2R DACs". In order to make a generalization like that with any degree of confidence, I would want to either compare two DACs that are as identical as possible in every other respect, including their analog circuitry and oversampling rate, and ONLY differ in the fact that one uses an R2R chip while the other uses a D-S chip, or a significant variety of products of each type by several different vendors.
     
    I also notice, from various descriptions, that the Audio GD DAC19 has several other interesting features, including (in the older model) using the PMD100 digital oversampling filter. This makes direct comparison to other dissimilar devices even more difficult (the audible differences between that digital filter and those used in other DACs MIGHT turn out to be more audible than the differences between R2R and D-S DACs). That could also turn out to NOT be true, but my point stands - that there are too many variables here to make a generalization based on them.
     
    What the experiences you describe suggest to me is simply that R2R DACs are quite capable of sounding very good - which I don't at all doubt.
    However, that doesn't prove that ALL R2R DACs sound good, or that ALL D-S DACs don't.
     
    nicolo likes this.
  11. KeithEmo
     
    With a complex device like a DAC chip, you can't exactly isolate things like price, demand, development costs, and sales volume.
     
    At this moment, you can get a Delta-Sigma DAC chip that contains pretty well all of the complex functionality you need to make an audio DAC (the DAC, the oversampling filter, and most of the logic) for between $1.50 and $3 each - in quantity. Sabre DACs, which include all of those things, but also add a few other special features, and have a "known brand" name to increase their value, go for just under $20 in quantity. (However, I'll bet that those companies spent at least several million dollars developing those chips.) And, at the moment, an R2R DAC chip will cost you three or four times that much - and then you'll have to spend money to design the support circuitry and glue logic to go with it, and then build that.
     
    However, the real reason this will cost you so much is that the economies of scale and availability are against you. The reason you'll have to design and build that support circuitry yourself is that you'll be using a DAC chip that is either somewhat out of date, or wasn't designed for audio applications (otherwise it would have it built in). Basically, you'll be adapting a part that wasn't intended for exactly what you're using it for. And you'll have to pay a guy to figure out how to get it to work in that application, and pay more people to build it, and buy parts - and all to sell a few hundred, or a few thousand, products. Obviously, you have to add enough to the cost of each unit you sell to pay for those development costs as well as what it costs to build it.
     
    To put it bluntly, it may well cost YOU $80 for that R2R DAC chip, and $200 per unit to design and build the extra circuitry that you'd need to use an available R2R DAC chip for modern audio applications. However, Texas Instruments, who knows more about it than you do, can design it much better..... and, while they may spend $1 million developing the design, they can add it to the chip for $1 each, and sell it to you for $2 - at a nice profit. They can also sell that whole chip for $20 at a profit if they sell enough of them. However, they can't (and won't) do that unless they're pretty sure they can sell at least a few million of them.
     
    My problem with a lot of the current hype about R2R DACs is that most of it is really just guesswork and supposition. I'll take your word for it that SOME R2R DACs sound better than SOME D-S DACs. However, I'm not at all convinced that the general case there is proven. And, beyond even that, even assuming it did turn out to be true, that still doesn't explain WHY - which is sort of important. What EXACTLY do you claim that R2R DACs do better that accounts for the difference in sound? The purpose of ALL DACs is the same - to take in digital audio and put out equivalent analog audio. If R2R DACs are really better than D-S DACs, then the analog audio they produce MUST somehow be different. (It can't be better "just because of the way it works" - because the way it works really doesn't matter; only the results matter.) Therefore, assuming that difference exists, we can measure it, figure out why it happens, and make sure it happens in the next chip we design.
     
    Perhaps, after some actual research, we will find out for sure that most current R2R DACs do indeed sound better than most D-S DACs.
    If we do, then we can move on to finding out WHY they sound different.
    If that happens, then maybe we'll find out that there's some wonderful thing that D-S DACs just can't do.
    Or maybe we'll find out that any $2 D-S DAC can sound better than any R2R DAC ever made - if only we change one little parameter that nobody thought was important before.
     
    To get back to your original question.....
     
    Delta-Sigma DACs were DESIGNED to do everything that most DAC customers wanted, and to do it better and cheaper than R2R DACs.
    Perhaps they missed something important.
    (Or perhaps 99.9% of their customers are wildly satisfied, and only the few audiophiles who make up the other 0.1% of their market consider the project a failure.)
     
    Either way, it sure seems like it makes more sense to actually figure out what's going on instead of sitting around complaining: "Cars make too much smog, we should all go back to horses."
     
  12. evillamer
    I think the sound quality for common folks has improved quite abit in the past 10 years when you compare 2015 to 2005.  Just take your Iphone 6/6Plus and compare it to your Ipod Classic 5th/6th gen and compare the sound quality. Not sure if its solely due to the DAC chip or other things in the chain like amps and software/mixer or just engineering improvements. This group of people don't really care about how many bits or what kind of digital filter is their device using.
     
    But for audiophiles in this head-fi community in question, we seek the most authentic/natural/musical reproduction thus we will access and evaluate gears and will pay quite abit more than common folks just for any improvements even if it's only slightly better. If you search around head-fi forums, you will find many written impressions from those who upgraded from audiophile grade Sigma Delta Dacs to audiophile grade R2R dac and most, if not all these impressions will be positive. All of them will tell you in one form or another that vocals brings more emotional connection, instruments sound more real and music flows more naturally. Does this mean that Sigma Delta dacs don't have it's place in Audiophile land? No. We have to thank companies like ESS tech who pushed sigma delta sound quality boundaries and allowed for more DACs variety in the audio marketplace especially in the <$1k price range. But I think in 2015, it is high time we "encourage" these semiconductor companies to come out with better audio chips, especially companies like Ti and AD(except AKM & ESS) who has not release any new improved top of the line  designs for quite some time.
     
    I brought my non-audiophile sister and brother-in-law to listen to my R2R setup(just audiogd m7+m9+Yamaha HS8) with some live concert music, and they said that my system sound so real, they feel as if they were in seating in the live concert right now.
     
    ciphercomplete likes this.
  13. ciphercomplete
    [​IMG]
    I guess if you were on the supreme court you would be a hardline textualist.  Just substitute "magic" for superior or just good sound quality, but something tells me that you are being dense on purpose.  I'm not trying to be argumentative here but seriously?!!?
     
     
    Well which is saying what I said in another way.  In fact I stated a couple of pages back that IMO NOS/R2R dacs suck.  You have spent many paragraphs arguing that chips don't make a big deal (or not at all) not I.  A few of us have heard and compared a great many SD and R2R dacs ourselves.  So are we just crazy?  Did we all just happen to mostly hear SD dacs that suck while lucking up and only hearing R2R dacs that are great?  I never said that all the SD dacs and cd players I have heard were bad.  I quite liked the Tentlabs and the Perfectwave DAC (unsure of which version) and many others I just wouldnt buy one when I can get a Lite Audio DAC 83, Master 7 or Yggy.    
     
    evillamer and Argo Duck like this.
  14. evillamer
    On the topic of Apple.
     
    It seems that in the newly released IOS 8.4 and Itunes 12.1.27, Apple might have done some changes to their software audio layer. Sound Quality seems much improved. Much better clarity. Try it for yourself.
     
  15. jcx
    dCS was pretty well received - "Ring DAC" is essentially a Delta-Sigma thermometer code DAC with Dynamic Element Matching -  modern audio DS DAC DEM is considerably advanced over theirs  
     
     
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