From: "oryoki2000" <>
> Moving to a higher price bracket, the Fostex FR-2 records BWF to
> Compactflash cards and hard discs in PCMCIA (PC Card) format. The
> advantages of the FR-2 are a better quality pre-amp, and the ability
> to select higher sampling rates (all the way up to 24/192 if you're
> using a fast flash card, 24/96 for the hard disc). Get a DVD burner
> and create your own DVD-A discs!
Pohlman in Principles of Digital Audio had some points about the
limitations of a practical 24 bit recorder, or at least the A/D section
that might be worthwhile to read if thinking about going 24 bit. There's
a bunch to it but the gist of it is that such fine subdivisions on the
usual voltage used are less than the inherent thermal noise of some of
the components. It's a matter of thinking of it as voltages rather than
dB. In voltage terms the fine increment is very fine. He cites 2 volts
fullscale, where the increment step is 0.1 microvolts. Less than the
thermal noise from one resistor.
I'm still working my way through sections of the book. And this section
I need to reread a few more times to get it all. But, if nothing else
he's definitely saying that anything like true 24 bit accuracy is going
to require a extremely high quality A/D section. Something that's not
too likely in lower price points. Makes me wonder about the inexpensive
stuff claiming 24 bit. They may be producing 24 bit, but not doing it
accurately.
Walt
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