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thosewhochosecheese
34
Aug 10, 2018
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Beyond the outright copy of the PCB design (and therefore circuit design) of someone else's work, I have to say there's a more pragmatic reason to avoid this R-2R DAC.
R-2R is simple, cheap, and I'm all for that - They're great for up to 10-12 bit resolution, and maybe slightly more (up to about 14bits).
Of course - they'll 'operate' up to 24 or 32 (or 128) bits - whatever you can build (and sell?) will work, but the resolution suffers , greatly, beyond about 10 bits for 0.1% SMT resistors, or beyond about 14 bits for well-matched, trimmed, 0.005%/ single-digit ppm temperature drift (typically thru-hole) resistors.
The problem is that when a digital input rolls over, for example, from 01111111 to 10000000, (and there are many, many, similar roll-overs in the digital domain), the tolerance on the MSB must be smaller than about 1/2 the LSB -otherwise you get non-monotonicity (relatively large local non-linearity) which is inherently bad for audio (not to mention the transients that need to be filtered out). As you add bits (up to +/-24 bits in this product, which is actually 25 bits), the required tolerance is impossibly tight. Even with trimming (whether laser or network, etc.), the tempco of the resistors also results in non-linearities due to slight temperature changes and gradients (unavoidable with dynamically changing signals).
Of course, this assumes that one can hear non-linearities in the lowest levels of noise & high resolution - some can, others can't, and some others can but don't let it ruin a good time (music is usually supposed to be a good time?). And if you choose to go R-2R, then at least use trimmed networks - they'll match better than even high-dollar discrete resistors (and WAY better than discrete SMT resistors).
Analog Devices' AD5791 is an R-2R based DAC, that i believe is used in some audio DAC's, and it benefits tremendously from highly-trimmed R-2R ladder in silicon - not discrete - which provides excellent TCR matching, among other benefits. But it's actually a 14 bit R-2R ladder with specially trimmed upper 6 bits (as 63 individual stages - not part of the ladder used in the lower 14 bits). This is an advantage that a discrete solution does not have. However - this DAC is aimed largely at applications where DC performance & adjustability are key - not linearity or non-monotonicity in reproducing complex & subtle audio - things like programmable power supplies and test equipment. In my opinion, although the AD5791 (and probably a couple other similar integrated & trimmed R-2R DACs) sounds wonderful - it still doesn't live up to the expectations of '20 bit' in terms of audio DAC performance - it's probably no better than 16 bit. But the area where the loss occurs just isn't glaringly obvious to most listeners - it only falls short in the finest resolved signal levels that honestly, most people can't discern - but will be happy to convince themselves that it's superior to their old set - they've invested their money and emotions in it - because they've bought into the poetry and zen-like qualities offered. "It simply MUST be better - I'm sure I can hear it!"
But my objection stands - don't bother paying for a R-2R DAC that claims to be any better than about 14bits resolution (and be very skeptical of claims of better than 12 bits...)
Almost any other DAC technology is better for audio.
-David
Aug 10, 2018
ChuckDee
1906
Aug 10, 2018
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thosewhochosecheeseIf you see above, MD offered to have a 3rd party compare the designs, and received no response.
Aug 10, 2018
AmJosh
128
Aug 10, 2018
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thosewhochosecheeseWell said on the R-2R tech in general!! This is what marks the beginning of the snake oil :). Although, I do believe MD that the design itself may not be copy. I also believe that we as community grow and get better by learning from each other: mistakes and geniuses. So, as long as one is using existing technology as starting point to go further, I am all for it.
Aug 10, 2018
inmytaxi
175
Aug 10, 2018
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AmJoshSnake oil? Far from it. I use it because the EEs try to bring the signal intact to the ears, as opposed to sending a result of a math calculation. Can I hear the difference? Not really. But I feel authentic. And it does sound fantastic.
Aug 10, 2018
thosewhochosecheese
34
Aug 10, 2018
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inmytaxiYOU are THE target for this product! Can't hear the difference, but you feel authentic and enjoy it!
I say keep enjoying it! Honestly! - I'm sure it does sound wonderful - but I attribute that to the most significant 12 bits and to the 'story'. Because the least significant 16 bits are doing nothing for you except introducing very low-level distortion and noise (quite possibly euphonic - but still not what you're paying for).
I honestly believe the first 12 bits gets you to the party - and that's the ugly truth for 90% of the people, that is all they (we?) need. The yarn woven about R-2R just induces you to feel better when you sit down and listen to those 12 bits you're getting. At best, it's the glass of wine to warm you up a little emotionally.
Seriously - of course I can hear the difference between 12 bits and 16 bits, and given an excellent recording / master and subject, I can hear detail above that. 24 bits?- personally, I can't usually hear the benefit. If I have to concentrate to hear the difference - it's not going to matter when I Zimbra is playing - I'm not concentrating then.. I mean, who wants to be critically listening all the time? I'm trying to enjoy music. I confess (no apology) that I do love the gear as well, and can get distracted listening for differences - but once I get emotionally involved in the music, I may as well be listening to my old iRiver H10...
So it would be smart for all of us to be more honest with ourselves, as well as use critical thinking when interpreting the crap these guys spin about what they're selling - learn to identify the snake oil - some of it is legit.
In MY opinion*, R-2R is a step backward in terms of fidelity - but discrete R-2R is terrible - most of the claims are BS - (but the 1st 10 to 12 bits are good!). You can spend your money as you wish though - I'm not criticizing you - if the R-2R DAC is your glass of wine - enjoy!.
(*it's just an opinion - please feel free to disagree and call me names in the privacy of your own head)
Aug 10, 2018
inmytaxi
175
Aug 10, 2018
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thosewhochosecheeseI already have a cheap piece of schiit dac that will last me a lifetime. And I get to have a tube as well as seperates! how hifi am I?
Aug 10, 2018
xx0x0
93
Aug 14, 2018
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thosewhochosecheeseYou know what Grey code means, right?
Aug 14, 2018
thosewhochosecheese
34
Aug 14, 2018
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xx0x0Do I know what it "means"? I know what it "is".
Is this where I'm supposed to respond to a vaguely worded "I know more than you do, but won't elaborate" grenade?
Well, I didn't see any claims that the Airist uses Gray code internally? (but I didn't read the entire thread - maybe it's mentioned in the back-and-forth about IP, I'm not investing my time reading all that shit)
So, I'm quite sure that use of Gray code should help minimize glitches (not sure it's been proven in a DAC, but it's often used in ADC, which has symmetrical problems). But it still doesn't eliminate the fundamental physics problem of discrete resistor tolerance requirements decreasing to well beyond what's available even from 'aerospace / military grade'. It should reduce the glitches, but it won't eliminate them. It's possible that using dual R-2R DACS per channel would also help reduce glitches - there are other ways to minimize, but these are incremental improvements, valiant attempts to make up for a fundamental weakness. They don't solve the progressing resistor tolerance requirement.
So, are you just poking at my rationale against discrete R-2R, or are you defending the Airist Audio R-2R DAC implying it uses Gray code internally? I mean, it's possible, it looks like they're using a Xilinx CPLD, so anything is possible - except getting >12-14 bits resolution using discrete R-2R ladder ;-)
Aug 14, 2018
thosewhochosecheese
34
Aug 14, 2018
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inmytaxiQuite hifi!
I have the Magni2. They make things very well, to be honest. And they offer a nice spread of options.
Relevant to this thread: Not everything any HiFi manufacturer offers is a smart choice, or a good value. That decision is for the consumer to determine, and even the best manufacturer's reputation doesn't excuse me from using critical thinking and critical judgement. Then, I use my emotional thinking, and buy it if it makes me happy - because, you know - this is for music, and life is a one-way trip around the Sun a few times, the end..
Aug 14, 2018
PeteMtl
440
Aug 15, 2018
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thosewhochosecheeseThe king of the hill in R2R DAC was and still is the Philips Crown TDA1541A-S1 16 bit 176.4 khz oversampling chip, although now discontinued. I would buy anytime a reasonnably priced DAC from Massdrop if such a DAC would use such chipset. I know, i’m a dinosaur, the chip was introduced in the mid eighties and used in high end cd players for 15 to 20 years after, but I strongly think that 16 bit music cannot be better decoded than with that chipset. Just my 2 cents on R2R decoding. By the way, delta sigma decoding using approximation between two samples is a false issue and cannot be worse than high fidelity analog recording, which is nothing less than realtime approximation of the music being recorded. Such approximation is so precise that there is no way in this world you could notice it. All of this R2R vs. Delta Sigma debate is extreme first quality snake oil in my opinion. Let’s listen to music instead!
Aug 15, 2018
thosewhochosecheese
34
Aug 16, 2018
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PeteMtlAgreed ! on all counts!
I am not a delta-sigma vs R2R snob - the delta-sigma is clearly superior technically, of the two, but:
1st: Sound reproduction is merely a facsimile of live - some tech can get closer than others, but nothing is 100%
2nd: Very little recorded music actually benefits from extreme dynamic range, but some does certainly justify extreme 'hi-fi'. More often, the soul of so much music is in the top 16 bits (and frequently 12 to 14)
3rd: Buffers & power supplies are generally more important than the DAC itself. Don't get religious about tech!
4th: Give yourself permission - it's okay if you don't hear what the reviewer heard - don't be a sheep! All human ears have different frequency responses & preferences - and asymmetry! No need to maintain 'purity' - strive for enjoyment! And use critical thinking, if THD & 2nd order harmonics "do it" for you - even for a genre or two of your musical preferences - it's okay to 'give in'! Buy & use what you enjoy! (not what others think you should like).
- by the way, although redbook CD are considered archaic today, the only CD transport I still use is my 1985( [edit - 1987] Magnavox CDB650, which uses the TDA1541 (and modded to the TDA1541A-S1!) It just sounded better than my buddies Sonys...
Aug 16, 2018
Jimee23
0
Nov 10, 2019
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thosewhochosecheeseWell if you havent heard it how can you tell us not to buy it. This is a nice upgrade from the Schiit Modi Multibit. Bass and soundstage is a good improvement and the DAC is reasonably priced. Sorry but I'm not into the technical aspect of audio gear. My opinion always comes after I hear it before technical specs. What DAC should we be buying if not this at this price point?
Nov 10, 2019
thosewhochosecheese
34
Nov 11, 2019
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Jimee23I didn't tell anyone not to buy it. I did suggest not paying for products that make misleading statements - but don't feel like this was intended for you! It was only meant for people who are open to others' opinions. And it was offered freely with no intention of persuading anyone - just open unsolicited opinion. So many people have read it, found it worthless and ignored it. Perfect. I don't know what separates an audiophile from their money - but I know R2R DACs, and their strengths and weaknesses, and I know when a resolution claim is worthless. Still - please don't read that as telling you what to do - I don't know you, and I think I made it very clear that audio is a very personal experience, and I did recommend that you buy whatever makes you happy (and it was not sarcastic or facetious). I believe what I wrote was (this is a quote): "Buy & use what you enjoy! (not what others think you should like)". I did say that the AD5791 (in a well laid-out PCB) sounds wonderful - but it does not equate to 20bit resolution. I have not heard the AIRIST product - but I don't expect it to be any better than the AD5791. In my opinion, the pursuit of euphonious performance (let alone purist performance) is too often a distraction from immersing oneself in the music itself. Some of the best memories I have of music (live and recorded) were via some very compromised (even mono) fidelity equipment. And your last question (which I'm fairly sure was disingenuous - you wouldn't want my opinion - so why would you ask?) -I don't have any DAC recommendations for you - I never claimed to - look for an argument with someone else...
Nov 11, 2019
Jimee23
0
Nov 11, 2019
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thosewhochosecheeseOk I apologize for jumping to conclusions. And I was serious about a DAC recommendation. I dont know how to make a DAC from scratch using the analog devices chip. I was hoping you knew a DAC around a similar price point that would be better than this DAC. Or perhaps one that was a little more expensive but was up to par with your standards.
Nov 11, 2019
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