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In Reply to: RE: Thankfully the board in question comes with choice of... posted by Tony Lauck on September 09, 2015 at 19:16:41
Darn if wasn't right there in Wikipedia.
>"The required accuracy doubles with each additional bit—for 8 bits, the accuracy required will be better than 1/256 (0.4%).
>On a printed circuit board, using discrete components, resistors of 1% accuracy would suffice for a 5 bit circuit, however with bit counts beyond this the cost of ever increasing precision resistors becomes prohibitive. For a 10 bit converter, even using 0.1% precision resistors would not guarantee monotonicity of output."
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Big speakers and little amps blew my mind!
Follow Ups:
"For a 10 bit converter, even using 0.1% precision resistors would not guarantee monotonicity of output."
OK... And that could be a lock-up nightmare in a digital feedback system. But just listening? Not so much.
The thing I'm not clear on (and geanted I've prolly not read every post) is what the problem is that using discrete networks is thought to address. I must admit that the notion rather appeals to me because, well, it's more tweakable. Things that would be absolute disasters in volume production can be opportunities for fine-tuning for individual users...
Rick
> " what the problem is that using discrete networks is thought to address."
I think it's sole purpose is an attempt at increased sound quality. Looks like it causes problems.
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Big speakers and little amps blew my mind!
Two reasons why discrete will have problems:
1. components not matched to sufficient tolerance
2. components drift from previously matched settings.
Temperature changes will cause drift, so it there is uneven heating of components there will be problems. Temperature differences can be minimized by putting all of the resistors on a single substrate, but then this won't be a discrete approach.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Thanks Tony. I think you and Abe are in agreement on this one. Now I'm thinking of the copper foil on those metal foil resistors. Wonder if when they oxidize it will change the resistance?
What about my question regarding the AD5791? What do you make of the quote from the spec sheet?
Thanks.
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Big speakers and little amps blew my mind!
I wouldn't take too much stock in theoretical type answers.
I'd get real information from people who actually "Modify" gear in real life.
There are plenty of forums that have people who like to mod gear and have tried many types of resistors in real-life scenarios.
Some folks over at Headfi, for example, did mod work to the Havana dac and other products and post detailed results and how-to's etc. For example bypassing the internal opamp of the PCM56P dac chip. I myself modded one of my Havana Dacs, replacing some 54 parts including Shinkoh Tantalum resistors, Schottky Diodes and much more.
Theory is great, but real-world in better imo.
Dynobots Audio
Music is the Bridge between Heaven and Earth - 音楽は天国と地球のかけ橋
> "Theory is great, but real-world in better imo."
I agree. The simple fact is these discreet R2R dacs are rated in the A+ category by Stereophile, and I am a big sceptic with journalists having been one, but you have to take their opinion into account.
In reading the reviews I came across one statement that stuck with me. The following is by Michael Lavorgna in a review of the Totaldac.
> "I compared the Totaldac to the Auralic Vega (see review). The Vega strikes me as another DAC that offers up superb detail yet in comparison to the Totaldac with PCM playback it sounded a bit processed and not as fully voiced in terms of tonal complexity. The Totaldac edges out the Vega playing back PCM data with a more natural and fluid sound and it even digs deeper into the recording. And that's an impressive feat I've only heard a small number of other DACs accomplish including the MSB The Analog DAC (see review) which also happens to be a R2R ladder DAC and the Meitner MA-2 (see review). And that's some mighty fine company indeed. With the Auralic Vega playing back DSD, the gap between it and the Totaldac closes somewhat and here's the interesting thing—the Totaldac in my experience closes the gap between PCM and DSD the tightest of the DACs I've heard here. Or to look at it another way, in my experience less costly DACs offer up some impressive performance when playing back DSD, equalling more expensive DACS playing back PCM. The other DACs I just rattled off also play back DSD and if I have one wish list item for the Totaldac it would be a checkmark next to DSD."
The important bit being, "in my experience less costly DACs offer up some impressive performance when playing back DSD, equalling more expensive DACS playing back PCM."
He is saying all this in relation to a $10K dollar discreet R2R dac. Sometimes reading reviews is reading dreary ad copy, and sometimes they let a little of what they think onto the printed page. This is one of those times.
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Big speakers and little amps blew my mind!
Yes sometimes writers do let their true feeling slip into an article, other times you kinda have to read between the lines.
I've got a few Dacs, been trying to get some of what I 'think' is the best offerings in different Dac chips/designs. As far as expensive vs less expensive goes I can attest that some less expensive Dacs, namely R2R do indeed deliver the goods. I have a $2500 PCM1704 Dac next to my $600 PCM56P Dac, while they sound different from each other, the $600 Dac has a certain...as the Japanese would say 'Umami', a yummy savory deliciousness.
FWIW, most of the gear I own I bought sight unseen and unheard. It was from reading reviews [between the lines] and what was said, cross referencing reviews and looking at the design etc. After about 6-8 months of this I can be pretty confident in my purchase. For the most part I have gotten what I expected out of components, sometimes gear pass my expectations others 'few' its goes right back on the selling block quick.
Dynobots Audio
Music is the Bridge between Heaven and Earth - 音楽は天国と地球のかけ橋
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