On Nov 29, 2004, at 2:14 PM, Richard Rauch wrote:
>  * I do not think that any of my sound hardware can sample at more
>    than 16 bits per sample.  Not with NetBSD drivers, anyway.
>    If I wanted to play with this, what are some rough guides to
>    the cost of such sound hardware?

All of the recent cards from Creative (SB Audigy and later) will handle 
24-bit sample rates.  As for drivers, consider:

http://www.opensound.com/osshw.html

>> The reason pro systems use 48KHz is they have a wider stop band, thus
>> lower pass band ripple. This enables cheaper or higher quality filters
>
> Low-pass/high-pass I gather has to do with passing frequences 
> below/above
> threshholds.  What is "ripple" in this context?

"ripple" means distortion outside of the frequency range that one 
actually wants the filter to apply to.  A filter or crossover can be 
described in terms of it's order: a 1st order filter has a rolloff of 6 
dB per octave, a 3rd order filter has a rolloff of 18 dB per octave, 
etc.

The steeper the rolloff, the better the quality of filter/x-over, only 
higher order filters also suffer from complex forms of distortion 
involving phase shift and poor transient response behavior which can 
distort or even reverse the polarity of parts of the signal.  1st-order 
filters/x-overs are "wider" filters since they aren't as steep, but are 
rather expensive to implement and are quite demanding on the speaker 
drivers:

http://www.thielaudio.com/THIEL_Web/Pages/faqtimephase.html#anchor564257
[ audio marketing, sure, but there are some good diagrams if you wander 
around ]

-- 
-Chuck