And that idea is something that I have difficulty accepting. But what this suggests is that depth perception has no limit to how good small signal accuracy needs to be. I am used/wedded to the idea that you decrease a distortion and error, and at some point the distortion/error becomes so small that it's inaudible. I ended up with 350 dB performance, and the incredible thing was even going from 330 dB to 350 dB still gave (slightly) better depth perception. Now using tracks that does not have depth encoded, still sounded flat, as they should do, so this was not something artificial I was creating. Then I kept pushing the design of the noise shaper, and repeated the listening tests, with every improvement in the noise shaper the depth got deeper with this track. I use a particular organ piece for depth, and using that track I could hear the organ was deeper in the sound stage - it was sounding more like the depth you get with a real organ in a cathedral. ![]() Going from 200 to 220 dB had no change in refinement, timbre, instrument separation and focus - but it did change the perception of depth. ![]() So with the Dave DAC project I had a massive FPGA, and 20 elements on the pulse array, and so I could have better noise shaper performance, so I could test my assumptions that 200 dB performance was good enough. But I heard very odd things when optimising the noise shapers for Hugo (Mojo is identical), and that meant that my assumption that 200 dB performance was good enough was wrong - the optimising was suggesting that I need better performance. In the past, I used to think that 200dB digital performance noise shaper was good enough - after all, that's better than 32 bit accuracy, and its about a thousand times more accurate than conventional high performance noise shapers (this is the performance I use with Mojo). On the small signal amplitude accuracy problem, I still have difficulties accepting that the brain can be so sensitive - that it needs no small signal error whatsoever to accurately perceive depth.
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