Richard Rauch wrote:
> On Sun, Nov 28, 2004 at 06:49:15PM -0500, Chuck Swiger wrote:
[ ... ]
> Do you have a number that you would suggest for a sampling rate
> for "typical" tapes?

Well, your standard 44.1kHz/16-bit sampling rate is very convenient and more 
than adequate in terms of resolution.  But you could convert to a 128kbs MP3 
format (also common and convenient :-) and probably not notice any significant 
loss in audio quality compared to the original tape beyond a mild dulling of 
the treble.

[ ... ]
>> The crucial factor missing in the popular understanding of digital audio is 
>> that "stairstep" signal produced by the DAC's *must* be put through a 
>> so-called brickwall or reconstruction filter at the Nyquist frequency, 
>> which is half of the sampling rate.  In plain English, the "stairstep" 
>> signal with square edges contains very high freqencies which go away when 
>> you filter them properly.
> 
> Does this also mean that, given the human hearing range (something
> like 20Hz to 20KHz in rough terms?), CD quality recording is nearly
> as good as one could get---for raw audio playback---no matter how
> good the tape is?

Yes, 20Hz to 20kHz is the "standard frequency range", and the sampling rate 
used by CDs can handle tones up to 22.05kHz with greater than 96 dB S/N. 
Young people with good hearing can consciously perceive pure sine wave tones 
up to 24kHz or so, and there is some evidence that frequencies up to 30 kHz 
are detectable at a subconscious level.

A properly mastered CD is good enough that it is very likely that other parts 
of the audio playback system-- such as your speakers-- are going to limit the 
quality.  A CD is +/- 0.5 dB from 20Hz to 22Khz, whereas most speakers are 
down 3dB at ~60Hz or so.  There are darned few systems which can reproduce the 
lowest string on a bass guitar (E string, ~40 Hz) properly at 100dB volume, 
unless you've got a stereo system which costs multiple thousands of dollars.

Your average consumer CD player has better fidelity than the best 
consumer-grade tape setup by a long shot, although professional analog 
reel-to-reel multitrack tape recorders using Dolby-S can do slightly better 
than a CD (roughly comparible to 48kHz/24-bit).

-- 
-Chuck

PS: Check out: http://www.contrabass.com/pages/frequency.html