PAQRAT Applications

First off, understand that the PAQRAT won't give you 20-bit digital audio - all it will do is preserve such 20-bit audio if you already have it. So, before you run down to your local pro audio store, think about your A/D converters. You probably are going to need to upgrade them to take full advantage of a PAQRAT.

However, there's more to it. Virtually all DAW software and digital consoles do their arithmetic (er, DSP) at 24 bits. The reason for this is that in order to maintain accuracy during arithmetic, extra bits available for handling the overflow numbers of calculations without excessive rounding are needed to keep errors from accumulating as the arithmetic goes on.

Assuming your particular workstation or digital mixer will present the full 24-bit (or 20-bit) word at the AES/EBU output, such audio (even though originally from a 16-bit source) can be stored in a larger bit format. This permits multiple passes of DSP of a file without the accumulation of errors that would be encountered if you truncated and re-dithered to 16-bit for each such pass.

Finally, such 24-bit or 20-bit files are amenable to re-dithering at the 16-bit level to your audio advantage. The most common such scheme is Sony's Super Bit Mapping (SBM). Lexicon has their own dithering scheme called PONS (Psychoacoustically Optimized Noise System). These yield audio quality that is alleged to approximate 18-bit. However, you need to start with a 20-bit or better file in order to derive any benefit from such a strategy.

PAQRATs For Fun And Profit

So, if you have some 20-bit D/As, you can simply use an ADAT as a 20-bit dedicated stereo digital recorder.

Further, you can use to ADAT to store repeat passes of digital files out of your DAW or digital console for off-line signal processing with reduced signal degradation over multiple generations.

Further still, you can load mixed files onto ADAT via PAQRAT and send them off to a mastering room to be mastered using Super Bit Mapping or other enhanced re-dithering, giving enhanced resolution to your final 16-bit CD project.

Finally, and this isn't trivial at all, you can use your PAQRAT/ADAT setup to make really good and redundant (double copies) safeties of your mixes. The comfort in knowing that you have a pair of 20-bit safeties lying around that are better than the CD masters is serious comfort indeed.