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7. Re: Choosing the right sampling rate and sample size

Subject: 7. Re: Choosing the right sampling rate and sample size
From: "Dan Dugan" dandugan_1999
Date: Tue May 18, 2010 8:15 pm ((PDT))
>> While the truth is that higher sampling rates unequivocally result in =

>> greater bandwidth,
>
> I feel greater bandwidth is is not the primary reason for going to higher=
 sampling rates.  Doubling the sample rate - and this should be obvious fro=
m the term -  doubles the number of times per second the original analog si=
gnal is sampled, giving a more accurate representation of the information i=
n that waveform.  There is an article on the WSRS website written by Nagra'=
s John Owen that makes a similar point:
>
> "The sampling frequency and frequency response go hand-in-hand really, an=
d although using the Nyquist theory, 44.1 kHz is sufficient to record perfe=
ctly up to 22.05 kHz bandwidth, using higher sampling frequencies does appe=
ar to reconstitute the original sound more accurately."

John is a good friend, but he also is in the business of selling higher-sam=
ple-rate recorders...note the weasely "appear to reconstitute." No real dat=
a to support the claim.

The idea that higher sample rates are more accurate in the human audio band=
 is a myth of digital recording that will never die. There is no difference=
 except wider bandwidth. Wider bandwidth is a good thing for nature recordi=
ng, though.

> The benefit of recording at 24bit is largely dependant on the capabilitie=
s of the A/D used in the recorder. Many of the so-called 24bit recorders, e=
specially if the design is a few years old, have A/D signal to noise ratios=
 of less than 96dB, so there is very little to be gained recording at 24bit=
.  The FR2-LE uses an A/D chip with S/N of 95dB for example which effective=
ly makes it a 15-6 bit recorder. Raimund's recorder tests are performed at =
Message: 44.
Subject: 1khz/16bits (with one or two exceptions) which obscures the 
performance =
advantages of those recorders which are capable of more than 16bit performa=
nce.  The Olympus is a case in point, with substantial improvements to perf=
ormance when tested at 24bit.

Even with a noisy recorder, a 24-bit master has more room for processing la=
ter, no harm in turning it up in post.

It's a dirty little secret of audio engineering that even the best state-of=
-the art A-D converters only deliver about 21-bits of actual signal-to-nois=
e. That's more than we need, anyway.

-Dan





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