audioslavematt said:
A
compressor/
gate is a completely different piece of equipment. Don't let anyone con you into believing a
compressor will eliminate
feedback. It will most likely cause more problems.
A
compressor actually takes an average of a signal's strength and maintains it. If there's a
gate built into the
compressor as well, that's even better. The
gate functions separately from the
compressor.
That's not quite right (but very close!). Compressors work by checking to see if the average (root-mean-square, to be precise, but it isn't that important)
level is above a certain
level. If it is above that
level (called the
threshold), the signal is reduced by a specified amount (called the compression ratio). For example, if I set my
compressor to 3:1, for every three dB over the
threshold that comes in, 1 dB comes out. A
limiter works very similarly, but has a fixed ratio of infinity:1, so that the
level will never pass the
threshold. If the
level is below the
threshold, then nothing happens (unless a
gate works on it).
There are other settings on a
compressor such as attack and
release, but those can usually be left at the default position and work fine.
As far as compressors causing problems, that can be very true, but only if it is improperly set. If your
compressor is set such that it sounds good (what sounds good? That's your decision!
Play around with it and see for yourself), it won't be a problem and will actually help with a
feedback situation by limiting the
feedback's growth.
The thing that you have to really watch out for is the
gate settings. If the
threshold for the
gate is too high, your signal will cut out and sound really bad (just like Matt said).
Now, as far as
feedback destroyers go - I personally would not recommend one unless you have no time to set up an EQ properly (as others have pointed out). They can cause random problems such as if a singer carries a sustained note for long enough, they may think that it's
feedback. I would much rather have a 31-band EQ that I can use to notch out any particularly problematic
feedback frequencies with.