Because music compressors are used so frequently in home recording, it might be helpful for you to have some basic settings for various instruments to get you started.
Horns
It’s rare that a compressor is used on horns. The only time you may want to use one is if an unnatural variation exists in levels due to poor playing (although its preferred to to ride the faders to even the levels instead of trying to fix the problem with compression). Still, if you use a compressor, start with these settings:
Threshold: –8dB
Ratio: 2.5:1–3:1
Attack: Around 100 ms
Release: About 300 ms
Gain: Adjust so that the output level matches the input level. You don’t need much added gain.
Piano
As with other acoustic instruments, you probably wont need to use compression on a piano unless you're going for a specific effect or want to even out an erratic performance. Settings for effect can run the gamut; just dial in some settings and see what you get. Using compression to even an erratic piano performance takes a little more finesse. In this case, start with these mild settings:
Threshold: –10dB
Ratio: 1.5:1–2:1
Attack: 100–105 ms
Release: About 115 ms
Gain: Adjust so that the output level matches the input level. You don’t need much, if any, added gain.
Kick drum
The kick drum responds well to a compressor when tracking. For the most part, you can get by with settings that allow the initial attack to get through and that tame the boom a little. Sample settings would look like this:
Threshold: –6dB
Ratio: 4:1–6:1
Attack: 40–50 ms
Release: 200–300 ms
Gain: Adjust so that the output level matches the input level. You don’t need much added gain.
Snare drum
Adding compression to the snare drum is crucial if you want a tight, punchy sound. You have a lot of choices with the snare. The following settings are common and versatile:
Threshold: –4dB
Ratio: 4:1–6:1
Attack: 5–10 ms
Release: 125–175 ms
Gain: Adjust so that the output level matches the input level. You don’t need much added gain.
Hand drums
Compression is usually a good idea with hand drums because the drum can produce unpredictable transients. For most hand drums, start with the following settings:
Threshold: –6dB
Ratio: 3:1–6:1
Attack: 10–25 ms
Release: 100–300 ms
Gain: Adjust so that the output level matches the input level. You don’t need much added gain.
Percussion
Because percussion instruments have high sound levels and are prone to extreme transients, often you might want to use a little compression just to keep these transients from eating up headroom in the mix. Here are good starting points:
Threshold: –10dB
Ratio: 3:1–6:1
Attack: 10–20 ms
Release: About 50 ms
Gain: Adjust so that the output level matches the input level. You need a bit of added gain here.