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How a compressor works

Inside the compressor is a little gremlin that turns down the volume. That's it.
Really. HOW and WHEN he turns down the volume is determined by the instructions
you give him with the compressor controls.

THRESHOLD sets the gremlin's alarm clock. It is what tells him to wake up and start
doing what he does, i.e. turning down the volume. If you set the threshold at -10dB
then the gremlin just sleeps his lazy ass off, doing nothing at all until the signal
level goes above that threshold. A signal that peaked at anything lower than -10dB
will never wake up the gremlin and he'll never do a damn thing. (see why presets
could be problematic?) But once the signal goes above the threshold, the gremlin
rips off the sheets and springs into explosive action.

RATIO decides HOW MUCH the gremlin turns down the volume, and it acts
completely in relation to the threshold. If the ratio is set to 2:1, and the signal goes
ABOVE the THRESHOLD, then the gremlin will cut that signal in half. For example,
with -10 threshold, a signal that hits -5 (which is 5dB ABOVE -10) will be turned
down 2.5dB for an output of -7.5dB. Negative values can be confusing if you're not
used to thinking in such terms so re-read and ask questions if you're stuck. This is
important, and it does get instantly easier once you "get" it.

ATTACK is like a snooze button for the Gremlin's alarm clock. It lets the gremlin
sleep in for a little while. So if the THRESHOLD is set for -10dB, and the ATTACK is
set to, say, 50ms, then once the signal goes above -10dB, the gremlin will let the
first 50ms pass right by while he rubs his eyes and makes coffee. An attack of zero
means the gremlin will respond instantly, like a hard limiter, and will allow nothing
above threshold to get through unprocessed. Any slower attack means the gremlin
will allow the initial "punch" to "punch through" and will only later start to act on
the body of the signal.

RELEASE is like a mandatory overtime clock for the gremlin. It tells him to keep
working even after the signal has dropped below threshold. A release of zero means
strict Union rules-- once the signal drops below threshold, the whistle blows, and
the gremlin drops whatever he's doing and goes back to sleep. But a slower release
means the gremlin keeps compressing the signal even after it has dropped below
the threshold. This can lead to smoother tails and less "pumping" or "sucking"
artifacts that come from unnatural and rapid gain changes.