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What is a
Compressor/Limiter? Will it help my sound system and do I need one ?
I have been asked
these questions many times on the internet, So I thought I would
share what I know about them with you in this issues column.
What is a Compressor/Limiter?
A
compressor/limiter was invented for live sound engineers and
recording engineers. The reason is that they needed a way to stop
over signals from getting to the P.A. system or Tape recorder. Live
sound can be very dynamic and can overdrive the system if the input
fader is set to high. (sudden scream's into the mic/dropping the mic,
ect.) They had to be very fast with the faders to stop damage to the
sound system or tape overload before we had Compressor/Limiters.
What a compressor
does is lower the input signal by a pre-set amount when a over signal
from a live source is present, stopping the over signal from reaching
the amplifier and/or recorder being used. A compressor's output can
be adjusted.
A limiter is a
compressor whose output level stays the same, No matter its input level.
Will it help my
sound system ?
Oddly
enough.....Most don't know they already have a basic compressor in
there system.
Many name brand
amplifiers have them built in...They go by different name's (Peavey
calls it DDT.) And so do many other quality brands of amplifiers.
They are not user adjustable and some work differently than others,
but are a basic compressor to protect the amplifier/ speaker system.
And another point
is that the Recorded Music we play is already compressed. So to add a
outboard compressor/limiter to further compress the music not
necessary. The studio Engineers have better gear than we do for
setting the limits.
The one's who can
benefit from a compressor/limiter is KJ's ! There use in the guests
singing Mic/Mic's could save you a woofer/driver next time they drop
or scream into a Mic!
But for DJ's at
large.....There is no need. If your system has proper headroom the
on-board Limiter in your amplifier will be up to the job of
protecting the sound system.
A side note, Have
you seen a button on your Mixer or EQ or Amplifier that says "40
Hz Cut" ? If you have, place it in the "ON" position.
This is a filter that stops all frequencies below 40Hz from getting
to the amplifier. This is because most "Portable" speaker
systems can not reproduce sub frequencies below 40 Hz. And by not
filtering them out, Your amplifier is making frequencies that your
speakers can not reproduce anyway, wasting amplifier power and your
system headroom.
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