At 1:36 PM -0400 7/26/04, Walter Knapp wrote:
>From: Rob Danielson <>
>
>>
>> At 9:06 PM -0400 7/24/04, Walter Knapp wrote:
>>
>>> if so, the 24 bit equipment is wasting 4 bits per sample, they
>>>won't contribute to the
>>>accuracy. And that's under ideal conditions.
>>
> >
>> One non-ideal condition is when recording distant sound sources in
>> remote locations and overall sound file saturation is low. The extra
>> bits contribute to some verfy useful resolution. Rob D.
>
>Pohlmann's point is that, no they don't. The resolution you can get is
>20 bit or thereabouts, limited by the analog part of the A/D. Regardless
>of how many bits you have. The extra bits in 24 bit are resolving the
>electronic noise of the components of the A/D. The reason I say that
>it's ideal conditions is that we have only considered the error
>introduced in the A/D, not all the rest of the analog chain before. We
>are assuming it provided a perfect copy of the sound being recorded.
>
>As I noted, once digital if you wish to preserve what accuracy you got
>then before doing any processing you should resample to a much higher
>bit count. It's that transition from analog to digital we are talking
>about, not any processing beyond that. And since storing the data in a
>recorder is not processing the data to change it, no need to up the bit
>count for that.
>
>Walt
>
Mic, mic pre quality (low noise and low harmonic distortion
particularly) and favorable A-D characteristics ("quality" vs low
price ) do seem to be larger factors than 16 vs.24 bit recording
resolution, but I'm not sure my experience bears out Pohlmann's
assertion that field resolution is effectively maximized close to the
performance of 16 bits (if I understand this correctly). I've had a
half dozen experiences with bringing home both 16 and 24 bit files
from the same location through the same front end. It's easier to
work with the 24 bit files compared to the 16 bit files. There's more
"body" providing more subtle tonal/amplitude differentiation making
equalization changes easier and more effective. The lower the file
saturations, the more pronounced the difference. I do up-sample 16
bit recordings to 24 bits in post when I know they will go through
further changes downstream, but this does not create a file that
handles as well as a 24 bit orig. All plugs are converting/working
with 32 bit floating regardless of orig sample rate of course. Maybe
there are better A-D units/methods out there today than Pohlmann was
basing his analysis on. It looks like the 4th edition was printed in
2000. Rob D.
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