For a compression novice there will be significant online producer peer pressure to use compression whether you understand it or not. Make no mistake, compressors can make your music sound worse quite easily if you do not understand them. Do not rush here if you are starting out. A much better way to learn compression is to understand some basics and then apply.
- Threshold: level at which compression starts to take place.
- Ratio: amount of compression applied when the threshold has been exceeded.
- Attack: Speed at which level is reduced (a time constant) practically expressed in milliseconds.
- Release: Speed at which unity gain is restored (second time constant) also practically expressed in milliseconds.
- Make-up gain: A post compression gain control allowing the gain to be restored to that similar as the pre compression level (remember compression reduces the level of sound peaks).
Initial Practice
For the following practice I recommend a good pair of headphones so you can focus on the sound changes with less disturbance from room acoustics and/or other room noises.
The human voice is a good sound source to practice on. The human ear is very sensitive to any unnatural artifacts introduced into this important human sound.
I suggest setting up a track with some speech or singing on it and applying a compressor with these settings (compressors are employed in the insert point of a track most commonly). Ensure the loud peaks in the voice are peaking at -8dBFS and set the compressor as follows:
- Threshold -16dBFS
- Ratio to 10:1
- Attack to 5ms
- Release 200ms
When you play the voice track you should see activity on the gain reduction meter (amount of compression being applied). You should also be able to hear the voice level drop in synchronization with the meters activity. The main practical use of this meter serves to provide an indication of how much make-up gain to add in order to match the original signal level.
