Paco,
> What settings work best? <
If one setting worked best for everything, compressors would come with only one built-in preset and no knobs. Once you understand what a compressor does and how it works, you'll know how to set the knobs properly yourself. Following is a brief explanation that hopefully will get you started.
--Ethan
A compressor or limiter is an automatic volume control that reduces the volume when the input gets too loud. Originally they were used to prevent AM radio transmitters from distorting if the announcer got too close to the mike. Then some creative folks discovered that a compressor can sound cool as an effect on voices and musical instruments.
The primary controls on a compressor are:
Threshold - also called ceiling - This sets the point at which the automatic volume reduction kicks in. Below that volume the compressor does nothing. When the input gets above that level, the compressor reduces the volume automatically to keep the signal from getting much louder.
Attack time - how quickly the volume is reduced when the input exceeds the threshold. If it's too slow, then a short burst of loud music can get through and possibly cause distortion. So when using a compressor as a tool to prevent overload you generally want a very fast attack time. But when used on an electric bass to get a little more punch, 20-50 milliseconds is often good because that lets a little burst of the attack get through before the volume is reduced. So each note has a little extra "definition" but without the full length of the note being too loud.
Release time - how quickly the volume comes back up after being reduced. If it's too fast, you'll hear the volume as it goes up and down. That sound is called "pumping" or "breathing." Sometimes this sound is desirable, but often it is not. It depends on whether you're using the compressor as a tool to prevent overloading, or as an effect to create a cool sound or add more sustain to an instrument. If you don't want to hear the compressor work, set the release time fairly long (one second or more).
Compression ratio - 1:1 does nothing. 2:1 means if the input rises to 2 dB. above the threshold, the compressor will reduce the level by 1 dB. so now it's 1 dB. above. 10:1 means you have to get 10 dB. above the threshold for the output to go up by 1 dB.
