[sdiy] Advice

[Cornutt, David K]

> From: Glen [mailto:mclilith at charter.net]
> 
> Using a compressor for the job of *expanding* dynamics sounds 
> a bit like
> the fellow who's only tool was a hammer and every began to look like a
> nail...   ;)

Well, there's dynamic range, and then there's
*useful* dynamic range.  It's not at all uncommon to
have a situation where you have peaks that don't 
contribute much to the musicality of a track, but
they are so much higher than the average level that
they force the whole track to be recorded at a very
low level.  That limits the useful dynamic range for
most of the track, and the quiet bits wind up buried
in the noise.  Of course, the old-fashioned way to
control this is to ride the faders, but you can't
always react quickly enough, especially when you
are singing or playing the track yourself.  The
type of compression I'm talking about here is
really more in the neighborhood of peak limiting;
it allows you to bring the track's highest RMS
levels up closer to 0dB, so that the quiet parts
have more room to breathe above the noise floor.
That's one way that compression can help improve
dynamic range.

Recently a dancer friend of mine asked me to fix a
track from a Broadway sountrack for her.  She said
she was tired of having to fiddle with the studio's
sound system to get the track up to where she could
hear it every time she practices.  The track
contains a mix of spoken word and music parts.
It sounds like one actor was close-miked and the
rest of the cast and the orchestra were miked with
a stereo pair; the one actor's voice is a good 30-40
dB above everything else in the track.  I set up a
dbx 200LX to act essentially as a limiter, with
moderately fast attack and release, and some downward
expansion to kill vinyl noise during the silent
moments.  It worked like a charm; the voices are
now more in balance, the loud bits really hit you
in the face, and the quiet bits are audible but
still very subtle.  (I had to play with the attack
and release times some to get rid of some breathing.
I had thought originally that very fast attack and
release was the way to go, but a moderately fast
setting worked better.  I still haven't worked out
in my head what was happening there.)  That's an
example of what I call increasing the useful dynamic
range, even though in absolute terms one part of the
track has had its dynamic range reduced.

Yes, compression is way over-used in pop music.
That doesn't mean it's inherently a bad thing.
I might note that the pop producers are using it
as an effect; the compression is applied *after*
the track is recorded -- when it's too late to do
any good for dynamic range control.  The kind of
compression I'm talking about is applied ahead of
the audio entering the recording device (the example
above notwithstanding).