); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY > As one who has worked in the pro digital audio field for years, I can > tell you that sub-100 ps jitter very definitely can be heard, > depending on its spectrum. Modern sigma-delta ADCs and DACs use > oversampling clocks of 12 to 50 MHz for sample rates of 44.1 kHz to > 192 kHz at 24-bit resolution and achieve SNR and DNR of 120 dB or > better, integrated over the audio range. The noise floor can be -144 > dB or better and a 1-bit signal can be discerned. Higher-end > consumer gear do use these as well as pro equipment.
Can you show us the math behind this? If I calculate 1 / 192 kHz / 2^24 = 0.3 ps, my crude intuition says that at 192 kHz (~ 5 us) one ps of time jitter is roughly equivalent to about 2 bits of noise on a 24-bit DAC, yes? Similarly for a vintage 16-bit DAC at a modest 44.1 kHz, one bit of DAC noise is equivalent to ~300 ps of time jitter (using a calculation of 1 / 44.1kHz / 2^16 = 346 ps). Is this the right way to do the math? Am I even close? It seems to me that all short-term imperfections in timebase stability have the identical effect as short-term imperfections in DAC stability and is also related to the number of bits of resolution in each sample. So debates about signal fidelity, which are often framed in terms of sample rate (e.g., 44.1 vs. 192 kHz) or sample width (e.g., 16 bits vs. 24 bits), should equally discuss clock jitter parameters, no? Only, I rarely see much about the role of clock jitter in digital audio, or if I do, it's handwaving instead of real data. I don't want to get that far off time-nuts topics, but this does seem to be an interesting real-world application of precise time and I've not run across a scientific treatment of it, one that includes real performance measurements of various digital audio recording and playing devices, etc. It's also interesting when two list members disagree by so many tens of dB, so I'm hoping David and PHK can settle this for us. /tvb _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.