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Rick Powell
 
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Default 16 bit vs 24 bit, 44.1khz vs 48 khz <-- please explain

Jay - atldigi wrote in message ...

Rick understands that bit depth relates to amplitude and that DSP is
better with longer wordlengths. A small clarification is in order,
however. He seems to consider there to be extra headroom while
technically there is not, unless you change the zero reference. In other
words, increase the voltage that zero is referenced to. Nevermind
working at -10 or +4, you'll be using a new, nonstandard reference
voltage, and what about the analog electronics that probably can't
handle that voltage? You're asking for trouble for that reason and
several others (increasing the noise floor of the analog gear,
compatability, and more). Unless you want to do that, you really are
gaining what should be thought of as "footroom" more than headroom.

In practice some feel that you need to push a digital recording right up
to 0dB FS to "use all the bits". This really isn't as big an issue as
some would have you believe, as long as you use good gain stageing and
reasonable recording levels, especially with todays converters which
perform far better than much or the early crappy digital stuff. It
doesn't hurt to assumne that 24 bits gives you a little room to play
with, but unless you are recording a program with greater than average
dynamic range in a very quiet environment with excellent equipment and
minimal processing, you really aren't going to be able to take advantage
of those extra bits. Then again, they certainly don't hurt, and they
could help, so there's no reason not to. Still, it helps to understand
technically what's going on and when extra effort will pay off and when
if won't.


Jay, I'm not suggesting changing the zero reference. Correct the
following if I'm wrong, but as a mastering engineer, you would rather
take in a 2-track digital mix that peaked at -2db than one that peaks
at 0 dbfs and has a few "flat tops". Using a 24 bit format to record
or mix down to allows less artifacts towards the noise floor, given 2
"identical" sources (one recorded at 16 bit and one at 24 bit) peaking
at, say, -2db. And reduces the need (perceived or real) to "slam" the
recording all the way to 0 dbfs to take "full advantage" of the bit
depth.

If this is "footroom' instead of "headroom", isn't it still a margin
nonetheless?

RP