Compression is the mixing tool everyone uses and almost nobody understands at first. Turn a few knobs and the track sounds “different,” but is it better? This is audio compression explained in plain English for home recordists, with starting settings you can use today. It’s part of our main guide on how to mix and master a song at home, which walks through the whole mixing process.
A compressor automatically turns down a signal when it gets louder than a level you set (the threshold), by an amount set by the ratio. Attack sets how fast it reacts and release sets how fast it lets go. Then makeup gain brings the overall level back up, so quiet parts sound louder and the track feels more even.
Every DAW, including free ones, comes with a compressor that does all of this. You don’t need to buy anything to start.
The Controls, One at a Time
| Control | What it does | Typical starting range |
|---|---|---|
| Threshold | The level above which compression starts | Set so you see 3–6 dB of gain reduction |
| Ratio | How much the signal is reduced above the threshold | 2:1 to 4:1 for most sources |
| Attack | How fast the compressor reacts once the signal crosses the threshold | 5–30 ms |
| Release | How fast it stops compressing after the signal drops | 50–200 ms, or Auto |
| Knee | How gradually compression starts around the threshold | Soft for vocals, hard for punchy drums |
| Makeup gain | Turns the compressed signal back up | Match the bypassed level |
| Gain reduction meter | Shows how much the compressor is turning down | Watch it while you adjust |
Threshold
Think of the threshold as a line. Anything quieter passes through untouched. Anything louder gets turned down. On many compressors you lower the threshold to compress more. Sound On Sound points out that some compressors use a single “peak reduction” or “compression” knob that works the opposite way, so check how yours is labeled.
Ratio
At 4:1, for every 4 dB the signal goes over the threshold, only 1 dB comes out. A 2:1 ratio is gentle. 10:1 and above starts to act like a limiter.
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These two controls shape how compression sounds, and they’re the ones that confuse people most.
Attack
Attack is how quickly the compressor clamps down after the signal crosses the threshold.
- Fast attack (under about 5 ms): catches the very start of each note. Smooths peaks, but can dull the punch of drums and picked guitar.
- Slow attack (around 20–30 ms or more): lets the first hit of each note through before compressing. Keeps punch and snap.
Release
Release is how quickly the compressor lets go after the signal falls back below the threshold.
- Fast release: the level bounces back quickly. Can sound lively, but too fast causes distortion or pumping.
- Slow release: smoother, but too slow means the compressor never recovers and the next note gets squashed.
- Auto release: many compressors offer this, and it’s a good starting point if you’re unsure.
A good trick: set the release so the gain reduction meter returns to zero just before the next beat or phrase. It’ll breathe with the song.
Compressor Settings for Vocals
Vocals are the most compressed instrument in most mixes, because a singer’s volume naturally varies a lot between soft and loud words. Here are starting points. Always adjust by ear.
| Setting | Gentle vocal (ballad, worship) | Upfront vocal (pop, rock) |
|---|---|---|
| Ratio | 2:1 – 3:1 | 4:1 |
| Attack | 10–20 ms | 5–10 ms |
| Release | 80–150 ms or Auto | 50–100 ms or Auto |
| Gain reduction | 2–4 dB | 4–8 dB |
| Knee | Soft | Soft to medium |
Two-stage tip: instead of one compressor working hard, use two in a row, each doing 2–3 dB. It sounds more natural.
Order tip: most engineers EQ out rumble (a high-pass filter) before compressing, so the compressor doesn’t react to low-frequency noise.
For the full vocal chain, read how to mix vocals.
Starting Settings for Other Instruments
| Source | Ratio | Attack | Release | Gain reduction | Goal |
|---|---|---|---|---|---|
| Acoustic guitar | 2:1 – 3:1 | 10–20 ms | 100 ms / Auto | 2–4 dB | Even strumming |
| Electric guitar (clean) | 3:1 – 4:1 | 10–20 ms | 100 ms | 3–5 dB | Sustain and evenness |
| Electric guitar (distorted) | 2:1 or none | — | — | 0–2 dB | Distortion already compresses |
| Bass | 4:1 | 10–30 ms | 100–200 ms | 3–6 dB | Steady low end |
| Kick drum | 4:1 | 20–30 ms | 50–100 ms | 3–6 dB | Punch |
| Snare | 4:1 | 10–30 ms | 50–100 ms | 3–6 dB | Snap and body |
| Mix bus | 2:1 | 30 ms | Auto | 1–2 dB | “Glue” |
Distorted guitars are already heavily compressed by the distortion itself, so they often need little or none. For more on guitar in the mix, see how to mix electric guitar.
Parallel Compression (The “New York” Trick)
Parallel compression blends a heavily compressed copy of a track with the original, uncompressed track. You get the energy and thickness of hard compression while keeping the natural punch of the dry signal.
How to set it up:
- Create an aux or bus track and send your drums (or vocal) to it.
- Put a compressor on the bus with a high ratio, like 8:1 or more, fast attack, and enough threshold to get 10 dB or more of gain reduction. It should sound obviously squashed on its own.
- Turn the bus fader all the way down, then slowly bring it up under the original track until the sound gets fuller without losing its snap.
Many compressors now have a “mix” or “dry/wet” knob that does the same thing inside one plugin. Set it to around 30–50% wet as a starting point.
Parallel compression is especially popular on drums, but it works on vocals and bass too. It’s a great way to add weight without the flat, lifeless sound of heavy compression on the main track.
Step-by-Step: How to Set a Compressor
- Start with ratio 3:1, attack 10 ms, release Auto (or 100 ms).
- Lower the threshold until the gain reduction meter shows 3–6 dB on the loudest parts.
- Adjust attack. Slow it down if the track sounds dull or loses punch. Speed it up if peaks still jump out.
- Adjust release. Make the meter recover in time with the song’s rhythm.
- Add makeup gain until the compressed track is about as loud as the bypassed track.
- Bypass and compare at the same volume. Louder always sounds “better,” so level-match before you judge.
- Back off if in doubt. Over-compression is the most common beginner mistake.
Hardware Compression vs Plugins
Guitarists often meet compression first as a pedal. A compressor pedal evens out your playing before it hits the amp, which is a playing tool more than a mixing tool. Our guide to the best compressor pedals covers those. In a home studio, plugin compressors inside your DAW do the mixing job, and the stock compressor in GarageBand, Logic, Reaper, Cubase or any other DAW is plenty to learn on.
If you’re recording guitar at home, our guide to the best audio interfaces for guitar helps you get a clean signal into the computer before compression ever comes into play.
Common Compression Mistakes
Too much gain reduction. If the track sounds flat, lifeless or pumping, back off the threshold.
Comparing at different volumes. Always match levels when you bypass.
Fast attack on everything. It kills transients. Try slower attack on drums and picked parts.
Compressing to fix a bad performance. Compression evens out volume, but it can’t fix timing or tuning.
Compressing every track by default. Only compress when a track needs it.
Frequently Asked Questions
What does a compressor do in simple terms?
It turns down the loud parts of a track automatically, so the difference between loud and soft is smaller. After adding makeup gain, the whole track sounds more even and present.
What is a good ratio for vocals?
Start between 2:1 and 4:1. Gentle styles like ballads and worship often sit around 2:1 to 3:1, while upfront pop and rock vocals often use about 4:1. Adjust by ear.