Compression is the plugin people understand least and reach for most. You put it on a track, move some knobs, and something changes — but not obviously for the better. So you leave it there because you have been told you are supposed to.
Here is the whole thing in plain terms, and then the actual numbers.
What It Actually Does
A compressor is an automatic volume hand. When a sound gets louder than a level you set, it turns it down. That is it.
The point is not to make things quieter. It is to make the gap between the loudest and quietest parts smaller, so you can raise the whole thing afterwards. A vocal that jumps from a whisper to a shout becomes a vocal that sits steadily in the track.
The Two Knobs That Matter
Attack is how fast the hand moves. This is the one people get backwards. A slow attack lets the first hit through before clamping down — so the pick, the stick, the transient survives. That is what keeps things punchy. A fast attack grabs everything instantly, which is more controlled but duller.
Release is how fast the hand lets go. It should breathe with the music — recovering before the next note arrives. Too slow and the compressor never lets go, so everything sounds squashed and lifeless. Too fast and you hear it pumping.
"Slow attack keeps the punch. Release should breathe with the music."
Ratio, In One Line
Ratio is how hard the hand pushes. 2:1 is gentle glue that preserves dynamics. 3:1 is controlled levelling. 4:1 is real grip — bass, snare, anything that needs to stay put. Above 4:1 you are into limiting, which is a different job.
The Numbers
These are starting points, not laws. Dial them in, then trust your ears.
| Source | Ratio | Attack | Release | Gain Reduction |
|---|---|---|---|---|
| Lead vocal | 2:1–3:1 | 5–10 ms | 80 ms / auto | 3–6 dB |
| Backing vocals | 3:1–4:1 | 5–10 ms | 90 ms | 4–6 dB |
| Acoustic guitar | 2:1 | 20 ms | 150 ms | 2–3 dB |
| Electric guitar | 2:1–3:1 | 15 ms | 120 ms | 2–3 dB |
| Bass | 4:1 | 15–20 ms | 140 ms | 4–6 dB |
| Kick | 4:1 | 10–15 ms | 120 ms | 3–5 dB |
| Snare | 4:1 | 5–10 ms | 100 ms | 4–6 dB |
| Drum bus | 2:1 | slow | ~120 ms | 2–3 dB |
How to Know It Is Working
Watch the gain reduction meter, not the knobs. If it is barely moving, the compressor is doing nothing. If it is pinned at 10 dB on a vocal, you have crushed it.
The better test: bypass it. If bypassing makes the track sound obviously better, you have gone too far. If bypassing makes it sound uneven and jumpy, the compressor is earning its place.
Free: the one-page quick reference
Compression starting points for every instrument plus the frequency map, on a single page you can keep open while you mix. Free — just tell me where to send it.
Get the Free Sheet →Want the actual numbers for every instrument?
I put together a cheat sheet with the full chain for each instrument — the exact EQ moves, compression ratio, attack, release and gain reduction, plus effects and a complete mastering chain. It is the reference I use every day at Darkstorm Studios. Works with any DAW and any plugins.
See the Cheat Sheet →Two Compressors Beat One
If you need a lot of control, use two doing 2 to 3 dB each rather than one doing 6. The first catches the peaks gently, the second levels what is left. It sounds far more natural than a single compressor working hard, and it is how most professional vocal chains are actually built.