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DAC Poll: anybody who prefer listening to Delta Sigma single-bit over NOS multibit?
DAC Poll: anybody who prefer listening to Delta Sigma single-bit over NOS multibit?
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Old 10th December 2018, 03:19 PM   #1
ygg-it is offline ygg-it  Italy
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Default DAC Poll: anybody who prefer listening to Delta Sigma single-bit over NOS multibit?

Is there anybody here who prefer listening to Delta Sigma single-bit over NOS multibit DAC?

- don't think too many -
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Old 10th December 2018, 03:33 PM   #2
JensenHealey is offline JensenHealey  United Kingdom
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Since there are not many of the latter around in the wild these days, there are few who could answer. And there are a zillion other variables.

And really, truly tell the difference between 'good' ones of each type in a blind session? I seriously doubt it.
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Old 10th December 2018, 09:11 PM   #3
MarcelvdG is offline MarcelvdG  Netherlands
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Most home-made non-oversampling DACs nowadays have sin(x)/x roll-off, which at 44.1 kHz sampling frequency can well be audible.

For what it's worth, I was at a demo last month where someone had made three multibit sigma-delta DACs with PCM1794 chips. One had a normal oversampling filter, one just a zero-order hold and one a zero-order hold and an analogue filter that corrected for the sin(x)/x roll-off. I didn't hear any difference between the first and the third DAC and had the impression that the second had slightly less treble. Mind you, it was not a blind test.

I also demonstrated my own DAC, which has an oversampling filter with very little passband ripple and plenty of headroom for intersample overshoots, a properly (2 LSB peak-peak triangular) dithered sigma-delta modulator with a kind of embedded pulse width modulator and a single-bit two-tap FIRDAC. It was very much liked, also by people who normally only listen to non-oversampling DACs with sin(x)/x roll-off.

One possible explanation is that they liked it because of the attention paid to details, like the passband ripple (which relates to pre-echoes), the headroom and the dither.

Another one is that they were subconsciously impressed by the looks of it: most of them are used to a DAC being an IC on a small board, so they were rather surprised when I came with a wooden enclosure of 63 cm by 33 cm by 20 cm with a big four-layer board with an FPGA module and ten valves and a filter board with big potcores and two signal transformers.

Since the event took place in two rooms, a third explanation is that people who didn't like it fled to the other room. I can't possibly say which explanation is correct.

To get back on topic: I prefer single-bit sigma-delta, provided it has an embedded pulse width modulator and proper dithering, but that's strictly on theoretical grounds.
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Old 10th December 2018, 11:31 PM   #4
sgrossklass is offline sgrossklass  Germany
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Quote:
Originally Posted by MarcelvdG View Post
a properly (2 LSB peak-peak triangular) dithered sigma-delta modulator with a kind of embedded pulse width modulator and a single-bit two-tap FIRDAC.
I always thought it was impossible to properly dither a 1-bit DAC since you need about 3 bits or so? Is there some sort of trick that I missed?

I can't take NOS DACs seriously. Tinkerer stuff. They went out of fashion in the mid-'80s for good reasons. Even the last CD players with traditional multibit DACs had something like 4X or 8X oversampling. If I had to run a NOS DAC, I'd be resorting to computer-based playback with a nice software upsampler (e.g. SoX VHQ) to do 176.4 / 192 kHz at least.
Single-bit sigma delta can be cranky and needs all kinds of trickery to get jitter sensitivity and high frequency noise output down (switched capacitor filters etc.), but with those can deliver pretty good results, even on a lowish power budget.

Personally, I think multibit sigma delta is where it's at. I'm not going to argue with anything that yields a 130 dB dynamic range. Plus, there's chips like the CS4399 that can run in "NOS mode" if you really want to roll your own digital filter in software.
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Old 10th December 2018, 11:39 PM   #5
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by sgrossklass View Post
... I think multibit sigma delta is where it's at.
+1
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Old Yesterday, 12:05 AM   #6
jean-paul is offline jean-paul  Netherlands
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Sigma Delta. It has matured over the years. NOS multibit is old news and chips are becoming rare.

Quote:
Originally Posted by MarcelvdG View Post
Another one is that they were subconsciously impressed by the looks of it: most of them are used to a DAC being an IC on a small board, so they were rather surprised when I came with a wooden enclosure of 63 cm by 33 cm by 20 cm with a big four-layer board with an FPGA module and ten valves and a filter board with big potcores and two signal transformers.
Make that consciously as many audio people listen with their eyes. It really is better to not show the equipment until listening is over. Many tube people will automatically prefer anything that has tubes.
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Last edited by jean-paul; Yesterday at 12:12 AM.
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Old Yesterday, 04:05 AM   #7
abraxalito is offline abraxalito  United Kingdom
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I'm a fan of NOS DACs but they vary too much to generalize about how they sound against S-D DACs. S-D DACs also vary a lot, depending in the main on whether they use on-chip opamps for output stages.

If the comparison is a PWM-based single bit DAC (say STA326) against unfiltered multibit I'd go with the PWM DAC. If the multibit NOS is well filtered and doesn't include opamps then the multibit NOS would likely win.
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Old Yesterday, 05:44 AM   #8
MarcelvdG is offline MarcelvdG  Netherlands
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Quote:
Originally Posted by sgrossklass View Post
I always thought it was impossible to properly dither a 1-bit DAC since you need about 3 bits or so? Is there some sort of trick that I missed?
That's the embedded pulse width modulator. The quantizer has three bits, which are then converted to a single bit stream by a pulse width modulator algorithm. I also randomly rotate the PWM pattern to get rid of its distortion.

Quote:
Originally Posted by sgrossklass View Post
Personally, I think multibit sigma delta is where it's at. I'm not going to argue with anything that yields a 130 dB dynamic range. Plus, there's chips like the CS4399 that can run in "NOS mode" if you really want to roll your own digital filter in software.
Personally, I don't care whether the dynamic range is 80 dB, 130 dB or 200 dB. In all cases, I can't hear the noise at normal volumes.

Last edited by MarcelvdG; Yesterday at 05:48 AM.
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Old Yesterday, 06:04 AM   #9
ygg-it is offline ygg-it  Italy
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Thanks to all your venerable opinions (and, please, continue to post).

I don't want to resurrect the never-ending ancient diatribe between NOS multibit and DeltaSigma DAC, but I'm just asking this because at the end of my live tests I am really (but really!) undecided between two past glories: a DeltaSigma (CS4303) or NOS MultiBit (PCM56).


Beyond the technical peculirities of the single chips (the first RTZ, with pure digital differential outputs that gives full freedom to the designer to realize the entire analogue stage; the second with its pure current output and "zero crossing" noise trimmer which really minimise distortion at -80dB), both sound terrific to me (and better than modern commercial machines ) but totally different - given the same source, receiver and power supply.


It would be pretty easy for me, now finally, to mention pro and cons of the sound signature of the two DAC topologies, but if I just had to define the difference in perceived sound with a metaphor, I would say that if you enjoy "listening to music", you should get an NOS multibit; if you like more "musical details", then go for a delta-sigma.


If you allow me another comparison with other similar audio realities and perceptions, at first place I would put the diatribe if "Zero" Global Negative Feedback tube amplifiers sound better. At the end, if you think, Delta Sigma has a feedback loop too inside the modulator that (even if it is digital and not analog) it reduces distortion and extend response but potentially introduces time delays and artificials as well.


And with the passing time and with the hearing being lowered but much more trained, I find that I am getting more sensitive now to phase distortions than harmonic distortions and roll-off response.


Last edited by ygg-it; Yesterday at 06:24 AM.
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Old Yesterday, 06:51 AM   #10
Markw4 is offline Markw4  United States
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It is possible to make a multi-bit sigma delta dac very musical and very detailed at the same time, but it is usually fairly costly to do. Usually, we are talking well over $1,000 for one stereo dac, probably closer to $2,000. Or, you can make your own (not quite as good, but pretty close) for maybe around $250, but a lot of work in that case.
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