rasz_pl wrote:SB16 one looks pretty brick wall to me
Yeah, and that's fine. I don't question that. Look -- I know the discussion here is mostly relevant only to the SB16. I know your reply... this one:
rasz_pl wrote:used car salesman snakeoil. Neo, there are no stair steps.
... is in reference to the ... uh .. dubious FAQ entry posted earlier. I haven't scoped an SB16 playing an 8-bit waveform. I don't know whether there's any truth to that statement at all. On a traditional DAC, that is clocked to some multiple of either/or 44.1kHz or 48kHz, and has a sliding reconstruction filter (assuming it's not locked to one frequency), it would be mostly nonsense. "Mostly" only because you aren't going to get more than 8-bit resolution out of a 16-bit DAC playing an 8-bit wave, so there will be granularity issues with the resulting signal. But... not really any more or less than an 8-bit DAC, so the argument still fails as a reason why the SB16 would sound worse than an SB Pro with the same input. The only variable is quantization noise, which I feel is probably outside the scope of their answer, and probably not the cause of discrepancy anyway.
So what am I carrying on about? The headstrong notion that "stair-steps are a myth." They're just not. At least not always. That's not an opinion, it's fact, and I have a screen-shot from my scope (... somwhere) to prove it. 😀 I re-watched the Xiph video just now because I remember it being designed to prove a point -- I just didn't remember what. The point he was trying to make is that your end-product of digital audio, even at a "measly" 16-bit 44kHz, will not be plagued with jaggies. So you don't need to be so concerned with HD resolution downloads for music, nor terribly concerned about the DAC you use. And that is absolutely true.
(Although the supporting analog circuitry is probably worth some scrutiny. I took issue with his statement that passing a signal through an aliasing filter more than once won't band-limit the signal more. It definitely will. The DC-blocking cap is not infinitely large, and the aliasing filter is not infinitely high, so there will be a cumulative effect. Enough to care about? Depends on the -3dB points of the band-limiting. For the purposes of his argument, "no" will suffice most of the time.)
However, even he states -- counter to his argument, in a way -- that simple DACs that use a zero-order hold topology will output those "point in time samples" as a continuous voltage. This is exactly what I was talking about with the Burr-Brown DACs from the 80s and 90s that used a sample-and-hold IC to allow a single expensive DAC to multiplex several channels of audio. These old 90s sound cards worked the same way. It wasn't until DSP got cheap and easy enough to surpass ladder-DAC topologies that that was no longer the norm. Further, I highly doubt even the SB16 uses dithering to reduce the quantization noise on the Y axis.
This may not convince anyone of any different ideas than they had two pages ago. And, well, so be it. I can't imagine I have much to add that I haven't said yet. It does get to a point of semantics, like Scali said, of where you measure. Xiph guy is absolutely 100% correct in all his assertions. It's just that people with only a vague understanding of digital audio take his point and shove it down people's throats without understanding how and why it is both true and false. Not that I'm an expert -- he could walk circles around me in DSP theory, I'm sure. But I do understand enough to know his results require qualified assumptions before they can be taken as fact. He knows that as well, and even said at the end of the video that he took liberties.
That is all. 😎
EDIT: Oh!, actually I found the scope screen-shot I took while measuring the MT-32.
The attachment scope.jpg is no longer available
This is directly after the S&H stage, before the reconstruction filter. Kinda looks like stair-steps to me. So they don't exist AT ALL, hm? (Remember, Xiph guy said at one point "not even the digital signal". Which is actually true -- the digital samples are infinitely small points in time. It's the "not even" part that leads to confusion, I think.)