[1] Dealing with noise in analog production, eg pre/de emphasis (like Dolby) will increase its resolution, just like noise shaping can increase resolution of a digital production. In that sense they are similar,
[1a] though analog will always be at a disadvantage because dealing with the noise also messes with the signal.
[2] That is what I sort of had understood, ie assuming Nyquist's conditions hold, we would have infinite resolution (or close to it) if there were no quantisation errors.
[3] Your example of the Sabre chip "only" being able to achieve a DR of 140db under the most contrived conditions illustrates the point. ...
[3a] Now 140db is spectacular DR and way beyond any relevance to reproducing music but even so, it is nowhere near infinity.
1. No, they're not really similar at all. Pre/de emphasis does NOT increase the resolution of the signal and doesn't attempt to, what it does is decrease the amount of noise that will be added to the signal downstream (EG. That occurs from transmitting the analogue signal). If we take a theoretically perfect implementation of pre-de emphasis, what you would end up with is slightly lower resolution, IE. Exactly the same signal/resolution with some additional thermal noise. In contrast, dither linearises all the quantisation errors, effectively giving us perfect accuracy (infinite resolution) and then it's a case of moving the resultant dither noise to reveal that resolution (with noise-shaping).
1a. Other forms of noise reduction for acoustic/analogue do, as you say, "mess with the signal", IE. Introduce distortion, and the more noise you try to remove, the more distortion you introduce. Introducing distortion is not increasing resolution, it's reducing resolution. The trick of applying noise reduction is to reduce the amount of noise somewhat (typically by no more than a few dB), without the added distortion becoming audible/objectionable.
2. And that's why dither is an intrinsic part of digital audio, because it results in "no quantisation errors" and therefore effectively "infinite resolution" (but with dither noise).
3. Unfortunately, that figure doesn't really tell us much. Where it's measured/calculated makes a big difference because a DAC (or ADC) chip is by definition partly an analogue device and therefore subject to the physics of analogue signals (EG. At least some thermal noise) but of course now we're effectively talking about analogue, not digital.
3a. Yes, in practice we cannot achieve infinity resolution or even close to infinity because we always have to enter the analogue realm (and then the acoustic realm).
Us claiming that digital audio production has infinite resolution is almost as bad as those analog guys making that claim.
Not really, although we do have to be careful about what we mean, for example that we are in fact talking about digital audio and not about analogue audio, EG. Not about ADCs or DACs, which are partly analogue devices. And obviously, we're not talking about a digital audio system, which of course isn't actually a digital audio system, it's an analogue/acoustic system with some digital components/processes, which is therefore constrained by the limits of analogue circuitry and the laws of motion in creating an acoustic signal. And even when talking specifically about digital audio, there are still conditions to such a claim, for example, infinite resolution within a limited/specified audio frequency bandwidth. Furthermore, at the dynamic ranges and bit depths employed in digital audio, we run into the problem of what audio frequencies actually are, and therefore exactly what is meant by an infinite resolution of them. For example, a sound wave is a pressure wave travelling/propagating through a medium (air in our case), IE. A sound wave is the compression and rarefaction (movement) of air molecules, but what happens when we have a massive dynamic range? In the case of say 24bit (or 16bit with aggressive noise-shaping) the amount of energy represented at the bottom of the dynamic range (EG. -144dB) cannot compress and rarefy enough air molecules by a sufficient amount to propagate a sound wave and therefore a sound wave doesn't exist. In other words, a sound wave is itself a finite entity and therefore can't have infinite resolution. To rephrase your statement, we could say that digital audio production has a resolution/DR which exceeds the DR possible for a sound wave to actually exist and therefore effectively has infinite resolution. This is in stark contrast to analogue guys making that claim because in the case of an analogue audio production, we have numerous analogue units/signal paths each of which introduce cumulative distortion/noise, which brings the effective dynamic range of an analogue music production down to about 80dB at best (but more likely <60dB) and -80dB represents way more energy than is needed to propagate a sound wave. Digital audio also has numerous processes, each of which also introduces cumulative distortion/noise but professional audio production environments are 64bit float, so each process is adding noise/distortion at around the -350dB level and even a thousand or more still would not add up to enough for a sound wave to exist (and would therefore still effectively be infinite resolution).
G
