First, let me clarify that what I call “full dither” is random dither with an amplitude of one delta (i.e. going between -delta and +delta), where “delta” is the quantization step.
If you keep only the LSB in PCM (which uses mid-thread quantization), you’re left with a signal with 3 levels (-1, 0, +1). That’s one more than DSD, and it can still represent zero (i.e. can have zero power).
Now let’s say you use a mid-riser quantizer like DSD. In that case, you can’t fully dither a non-zero signal without going over +delta (or under -delta) every now and then, which would be mapped to +1.5 delta level, i.e. second positive level (or to -1.5 delta, i.e. the second negative level). You’ll end up with four total levels, i.e. (-1.5, -0.5, +0.5, +1.5). Now that’s two more than DSD. You’d have to halve the amplitude of dither to stay with two levels.
And that works only if you don’t shape. If you add noise shaping on top, you have to go with an even lower dither amplitude since the addition of error will surely go over these values. You end up with a fraction of what can be called “full dither”.
Yeah, that’s fine. Although it not really applicable concept in SDM, or noise-shaped PCM. You don’t seem to understand how modulators can be dithered.
No, keep it unsigned, it doesn’t matter. Any dithered or noise-shaped signal will never have zero power signal. Even less so any analog source through a decent ADC.
Now you are making assumptions about the modulator…
That is actually fine, since DSD specification allows up to +3 dB levels.
Error amplitude doesn’t actually matter at all.
Just fun reminder, ESS DAC chips also use 1-bit stream from their HyperStream modulator.
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AceRimmer
(Smoke me a kipper, I'll be back for breakfast!)
87
This is all fascinating stuff but…
I do have a suggestion for @Marian .
Please release your very own version of HQplayer, perfect it, sell it to many consumers, support it and continually fine tune and update it.
Then let’s see how level the field is.
Yes I realise this will get deleted by mods pretty quickly but …
I’d like to know which part I don’t understand. To the best of my knowledge, dithering is an integral part of the quantizer, which is independent of any modulation done around it. Thus, one can speak of dithering in the context of a quantizer, not a modulator.
Well. The thing is, there are people who talk little, but do more and know a lot; and people who know a little, do less and talk a lot. And sometimes one can be confused for the other on the surface. But the reality, the truth, is: credentials matter. Experience matters. True Understanding matters. 'Cause anyone with an internet connection and a keyboard can make an argument that takes up a lot of people’s time discussing and rebutting and clarifying… but it isn’t necessarily a worthwhile use of said time. Which, as we all should know, is finite.
We are discussing technology and the science behind it, not people. I also believe my comments are on subject, since the subject is DSD. If you feel my contributions are taking too much of your time, I apologize, and suggest you ignore them.
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AceRimmer
(Smoke me a kipper, I'll be back for breakfast!)
92
Of course not , but…
Might just be me but all I am seeing is a lot of back and forth with no acceptance of anyone else opinions or points of view which don’t truly count as contributions imho…but what do I know?
That is absolutely fine by me. I should probably mention that these are not my ideas, they are based on scientific research on the subject. And I do appreciate @jussi_laako for taking time to respond to me despite of my lack of credentials. But I guess this has gotten too much down to dirty details and may not benefit the discussion.
That’s my goal too. If I say something provenly wrong, I would like to know.
Just to make it clear, I’m not saying you should stay away from 1-bit systems for the purpose of reproduction. As long as the in-band noise is very low (say -120dB or below), it should not be audible, and you can still benefit from its simplicity.
My point was that the term “uncorrelated DSD noise” is not a thing and should not be used. I don’t think my argument based on the constancy of DSD power has been refuted yet.
Is any of this technical discussion related to the sound of DSD? The OP has already intervened once in post 28. I’m lost, I cannot follow any of it or what its relevance is.
If I believe a statement is not accurate, regardless of the subject, I think it’s worth pointing it out, even if that runs the risk of derailing the conversation.
It’s all good. Quite an interesting discussion, even if I don’t understand why DSD can’t be dithered. Credentials are not required, otherwise I’d never be able to post .
People are quite at liberty to accept Jussi’s comments as authoritative, given his knowledge and experience, but that shouldn’t inhibit argument or discussion.
I do not. Due to noise shaping, the noise level is so low inside the audible range that it won’t matter. Above that range, noise should not be a problem as long as analog filters remove it so that it won’t upset the analog chain and the speakers.
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