This has been chewed over in the 1021 mega thread. Reasonably detailed explanations of how sign magnitude architecture works were provided. Do some search.
Ok, so sign magnitude is the key here, not that there is much hope me trying to understand it. Just noticing the 1704 and other R2R chip are using similar techniques to reach higher bit depths, rather than them having extremely precisely matched resistors, which makes a lot more sense.
Yes, Sign Magnitude is the key, I have a little explanation on my website:
Soekris Engineering ApS, Products
There are a number of people who still don't get it and claims it's not possible to get low THD with discrete resistors, and although it is not that easy to understand, most here do get it.....
Over at SBAF, a dac1541 have been tested and especially the dynamic range at post #19 & #20 is impressive, you could still see a sinus at -110 dB, and visible at a FFT down to -140 dB.
If you look at the PCM1704 datasheet they show a sinus at -120 dB that only a Sign Magnitude DAC can do, Burr-Brown is the only company to do that, but they was also the only one to ever do a Sign Magnitude DAC chip....
More than 24 bits are useful to have when you have a digital volume control, like all my DACs do.
Could you please comment on those SINAD measurements - the DAM didn't seem to fare so well in this regard? Or is it something odd with those measurements? There are a few here on diyaudio who refer to these...
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I presume the SINAD measurements are done at 0 dB. The question is how the ranking would be at -40 or -60 dB level... (using digital volume control)
Fedde
Fedde
The problem with SINAD or THD+N is the Noise part, you don't see much when at lower levels you basically just measure the noise.... Look at the FFTs instead, there are no distortion products at low levels.
Yes as one is signal correlated (dist) and the other isn't (shouldn't be at least). But if it is, it's bad - also. I mean if noise changes as signal changes...
But not for all DACs apperently as they some perform some 20-30 dB better than the DAM - how is this? I still dont get it.
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But not for all DACs apperently as they some perform some 20-30 dB better than the DAM - how is this? I still dont get it.
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So if noise it about the same, then it must be dist that is higher - no? At high signal levels.
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Thanks for this gem, have always ignored them but they're great for the odd laugh.
" The output is simple: there is no audible difference. There just isn't to my ears. "
😛😛😛
" The output is simple: there is no audible difference. There just isn't to my ears. "
😛😛😛
Who are you quoting if I may ask? "Them" = ASR?
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Yes I see it now, it was from the second link I posted.
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Yes I see it now, it was from the second link I posted.
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It's no secret that a discrete R-2R DAC have higher THD at 0 dB signal level, so what ?? Which one do you prefer to listen to ?
And isn't SINAD really an old measurement used to evaluation sound quality in communication systems ?
And ASR is fun to follow, but there are usually no problems with their measurements, but their conclusions can be interesting....
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For the sake of discussion what happens with extra bits when the ladders accuracy is limiting the resolution, like a basic single ladder?
example from audio GD, it is a ''24 bit'' DAC. Is there a reason outside of marketing why they didnt just build 8-10 bit DAC instead of adding all those useless bits and increasing production cost and complexity of these boards?
the useless bits from the data wouldnt just be ignored?
example from audio GD, it is a ''24 bit'' DAC. Is there a reason outside of marketing why they didnt just build 8-10 bit DAC instead of adding all those useless bits and increasing production cost and complexity of these boards?
the useless bits from the data wouldnt just be ignored?
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