Compression Techniques

Compression is the most misunderstood tool in mixing. People either slap it on everything with no purpose, or avoid it entirely because they've been told it "ruins dynamics." Neither is helpful.

This guide is about practical compression on real sources — vocals, drums, bass, the mix bus — with actual settings to start from. We're not covering the theory of how a compressor works. If you need that, read the Compression encyclopaedia entry first. You should also be comfortable with Gain Staging before you start compressing anything — if your levels are wrong going in, compression will only make them worse.

What You'll Need

• A DAW with a stock compressor (every DAW has one)
• A mix session with recorded tracks to work on
• A basic understanding of attack, release, ratio, and threshold
• Your ears — and the discipline to A/B with the compressor bypassed

Step 1 — Vocal Compression

Vocals are the most common thing you'll compress, and the place where compression makes the biggest difference. The human voice has a wide dynamic range — whispers to belts — and compression evens that out so the vocal sits in the mix without constant fader rides.

Start here:

• Ratio: 3:1
• Attack: 10–30 ms (medium — lets the consonants through)
• Release: 50–100 ms (fast enough to recover before the next phrase)
• Threshold: Set until you're getting 3–6 dB of gain reduction on peaks

The vocal should sound more even without sounding squashed. If it starts to feel flat and lifeless, your ratio is too high or your attack is too fast. Back off. The goal is consistency, not destruction.

Listen for the quiet words in a phrase — they should come up slightly. Listen for the loud words — they should be tamed, not killed. If you can hear the compressor working, you're probably overdoing it.

Step 2 — Drum Compression

Drums are where compression gets interesting, because the same compressor with different settings does completely different things.

For punch (letting transients through):

• Attack: 30+ ms (slow — the transient passes before the compressor grabs)
• Release: Fast (50–100 ms)
• Ratio: 4:1
• GR: 3–6 dB

This lets the initial snap of the kick or snare through, then pulls down the sustain. The result is a punchier, more aggressive drum sound.

For sustain and body:

• Attack: Fast (1–5 ms)
• Release: Medium (100–200 ms)
• Ratio: 3:1–4:1

This catches the transient and brings up the body of the drum. The room sound comes up, the sustain comes up. The drums sound fatter but less punchy. There's a trade-off — which is why parallel compression exists.

Parallel compression on drums: Send the drums to a bus with heavy compression — high ratio, fast attack, significant gain reduction. Blend that compressed signal underneath the dry drums. You get the sustain and density from the compressed signal and the transients from the dry. Best of both worlds. More on this in Step 5.

Step 3 — Bass Compression

Even dynamics are critical for bass. A bass that jumps around in level makes the whole mix feel unstable. You want it to sit — consistently, solidly, in the low end.

Start here:

• Ratio: 4:1
• Attack: Medium-fast (5–15 ms)
• Release: Medium (100–150 ms — fast enough to recover, slow enough not to distort)
• Threshold: Set until you're getting 4–8 dB of gain reduction

Bass compression should be fairly transparent. You're not going for character here — you're going for control. The bass should sit at a consistent level in the mix without the player's dynamics pulling it in and out. If individual notes are still jumping out after compression, you might need a second stage (see serial compression below) or some manual gain riding before the compressor.

Step 4 — Mix Bus Compression

Mix bus compression is where people get into trouble. It's the most powerful and the most dangerous application of compression — because it affects everything.

Start gentle:

• Ratio: 2:1
• Attack: ~30 ms (slow — you want transients to pass)
• Release: Auto, or slow (200–300 ms)
• Threshold: Set for 1–3 dB of gain reduction maximum

The goal is "glue" — making the mix feel like one cohesive thing rather than a collection of separate tracks. Good mix bus compression is invisible. You don't hear it working; you hear its absence when you bypass it and the mix falls apart slightly.

Too much and the mix pumps. You'll hear the volume ducking on every kick hit, the stereo image narrowing, the life draining out. If you can hear it pumping, pull the threshold back immediately.

Important: If you're going to use mix bus compression, put it on early in the mix process and mix into it. Don't slap it on at the end — it changes the balance of everything, and you'll have to remix.

Step 5 — Parallel Compression

Parallel compression is one of the most useful techniques in mixing. The concept is simple: blend a heavily compressed version of a signal with the original dry signal.

How to set it up:

1. Send the source (drums, vocals, whatever) to a bus
2. Insert a compressor on that bus with aggressive settings — high ratio (8:1 or higher), fast attack, significant gain reduction (10+ dB)
3. Pull the bus fader down to nothing
4. Bring it up slowly underneath the dry signal until you hear the density and sustain increase

The beauty is that the dry signal keeps all its transients and dynamics intact. The compressed bus adds body, sustain, and density underneath. You control the blend with the fader.

This works brilliantly on drums — you get a huge, dense drum sound without sacrificing the snap of the transients. It's equally effective on vocals, where it brings up the quiet details (breaths, room tone, subtle inflections) without squashing the loud moments.

Some compressor plugins have a mix/blend knob that does this internally. Same principle — dial back the mix to taste.

Step 6 — Serial Compression

Serial compression means running two compressors in series — one after the other — each doing light work.

Instead of one compressor doing 6 dB of gain reduction, you use two compressors each doing 2–3 dB. The result sounds more natural and transparent, because neither compressor is working hard enough to introduce obvious artefacts.

A typical serial chain:

1. First compressor: Gentle, slow settings for consistency. Catches the big dynamic swings. FET or VCA style.
2. Second compressor: Faster, more character. Shapes the tone. Optical or tube style.

The first compressor levels the playing field; the second adds colour and polish. Together they do more than either could alone without sounding processed.

This is especially effective on vocals and bass — sources where you need heavy gain reduction but can't afford it to sound compressed.

Common Mistakes

Compressing everything by default. Not every track needs compression. If the dynamics are already even — a well-played pad, a programmed synth, a sample — leave it alone. Compression should solve a problem, not be a habit.

Wrong attack time. Too fast and you kill the transients — drums lose their punch, guitars lose their pick attack, vocals lose their consonants. Too slow and the compressor misses the peaks entirely, doing nothing useful. Set the attack with intention.

Not matching levels. This is the big one. Compressed audio sounds "better" because it's louder — and louder always sounds better to human ears. When you A/B with the compressor bypassed, you must match the output level. Use the makeup gain to compensate for the gain reduction, then bypass. If the compressed version doesn't sound better at the same level, it probably isn't. You're just hearing volume, not improvement.

Using your eyes instead of your ears. A gain reduction meter bouncing to −6 dB means nothing on its own. Listen. Does the track sound better? Does it sit better in the mix? The numbers are a guide, not a target.

Too much mix bus compression. If your mix bus compressor is doing more than 3 dB of gain reduction, you're almost certainly overdoing it. Back off. Glue is subtle.

What's Next

Once you're comfortable with these workflows, move on to:

Vocal Mixing → Gain Staging → Mastering Basics → dB Calculator → Loudness Calculator →

Recommendations

Further Reading

• Sound On Sound — Compression Made Easy
• Pensado's Place — Compressor Masterclass