What Does Attack Time Do on a Compressor? (And Why You're Probably Using It Backwards)

Compressor attack time is the single most important setting you’ll ever dial in. And there’s a very good chance you’re using it backwards.

Here’s what I mean. When I first started mixing, I thought fast instruments needed fast attack times. Drums are fast, right? So fast attack. Makes sense.

It doesn’t. A fast attack on a snare drum will make it sound flat, distant, and lifeless. A slow attack is what gives you punch. That’s completely counterintuitive if you’re just reading the manual, but it makes perfect sense once you understand what attack time is actually doing to your sound.

I’ve been teaching audio production at university level for close to a decade now, and this is the single biggest “aha” moment I see in students. Once attack time clicks, everything else about compression starts to make sense. So let’s get into it.

What Attack Time Actually Does

On a technical level, attack time controls how quickly the compressor clamps down after your signal crosses the threshold. A fast attack means the compressor reacts almost instantly. A slow attack means there’s a brief delay before full compression kicks in.

But here’s the thing – that technical definition doesn’t actually help you make better mixes. What matters is what attack time does to the sound. And to understand that, you need to think about every sound as having two parts.

The Front End and the Back End

This is the framework that changed how I think about compressor attack time, and it’s the thing I wish someone had explained to me years ago.

Every sound has a front end and a back end. The front end is the transient – the initial hit, the crack, the pick attack, the consonant. The back end is everything after that – the sustain, the decay, the body, the ring.

A snare drum has a sharp crack (front end) followed by a wash of tone and snare rattle (back end). A vocal has consonants that cut through (front end) and vowels that sustain (back end). A kick drum has the beater impact (front end) and the low-end boom (back end).

Attack time controls which part you hear more of.

Slow attack lets the front end through before the compressor engages. The transient passes, then the compressor clamps down on the back end. Result: the front end is relatively louder. You get more punch, more crack, more definition.

Fast attack catches the front end immediately. The compressor clamps down on the transient itself, pushing it down, which means the back end becomes relatively more prominent. Result: you hear more body, more sustain, more decay. The sound gets smoother – but it also loses its impact.

That’s why fast attack on a snare drum sounds mushy and distant. You’re literally compressing the crack out of it.

Why Compressor Attack Time Matters More Than Any Other Setting

I can change the ratio, the threshold, the release – they all matter. But attack time is the one that fundamentally changes the character of the sound. Threshold and ratio determine how much compression you get. Attack time determines what kind of compression you get.

Two compressors with identical threshold, ratio, and release settings will sound completely different if one has a 1ms attack and the other has a 30ms attack. One will sound smooth and controlled. The other will sound punchy and aggressive. Same amount of gain reduction, totally different vibe.

That’s why attack time deserves more of your attention than any other parameter on the compressor.

Fast vs Slow Attack: What It Sounds Like on Real Sources

Let’s get practical. Here’s what different attack time compressor settings actually do across common sources.

Drums (Kick, Snare, Toms)

Drum transients are incredibly fast – we’re talking single-digit milliseconds. So even what we’d call a “slow” attack on drums (10-30ms) is still letting just the very tip of the transient through before compression kicks in.

Below 10ms on a snare drum, and you’ll hear it go flat. The crack disappears, the snare sounds distant, squashed, kind of mushy. I wouldn’t ever directly compress a drum at any speed less than 10 milliseconds. I’m usually more of a 30 millisecond kind of guy, roughly, depending on the tempo.

10-30ms is the sweet zone for punchy drums. The transient passes through, the compressor engages on the body, and you get that satisfying crack with controlled sustain behind it.

Faster than 5ms and you’re into sustain territory – the drum sounds bigger and fatter, but the punch is gone. This can be intentional (some rock and ballad snare sounds are built on fast attack compression), but if you’re wondering why your snare isn’t cutting through the mix, this is probably why.

Starting point for punchy drums: 15-30ms attack, 80-150ms release, 4:1 ratio. Adjust from there.

Vocals

Vocals are interesting because they’re not as transient-heavy as drums, but consonants and plosives still act as front-end energy. A fast attack (1-5ms) will control those consonants aggressively, which can make the vocal sound smoother and more even but also duller and less present.

A medium attack (10-20ms) usually works well because it lets the consonants articulate naturally while controlling the dynamic range of the sustained vowel sounds.

If a vocal sounds like it’s lost its life after compression, slow the attack down. Let those consonants breathe.

Bass

Bass transients develop more slowly than drum transients, so attack times need to be longer to let the initial pluck or pick come through. If your bass sounds thin after compression, your attack is probably too fast and you’re catching the fundamental before it develops.

For punch on bass, try 20-50ms. For sustain and evening out note-to-note dynamics, 5-15ms with a longer release.

Acoustic Guitar

Pick transients on acoustic guitar are sharp but not as fast as drum hits. A medium attack (10-25ms) preserves the pick definition. Go too fast and the guitar loses its sparkle and presence. Go too slow and you’re barely compressing the loudest peaks.

The Common Mistakes (And How to Fix Them)

Here’s where compressor attack time settings go wrong most often.

“My snare/kick lost its punch”

This is almost always an attack time issue. Your attack is too fast – the compressor is clamping down on the transient before it gets through. Slow the attack until you hear the crack come back. Start at 20ms and work your way slower until it sounds right.

“Everything sounds squashed and lifeless”

Two possible causes: too much gain reduction overall, or attack time is too fast across multiple tracks. If you’ve got fast attack on your drums, bass, guitars, and vocals, you’ve compressed the front end out of everything. Nothing has any transient definition left.

Try this: go through your mix and slow the attack on every compressor by 10ms. See if the mix opens up.

“I can hear the compressor pumping”

This is usually a release time issue rather than attack, but attack plays a role. If your attack is very fast and your release is also fast, the compressor is cycling rapidly between clamping and releasing, which creates an audible pumping effect. Slow the release down until the gain reduction meter settles smoothly between hits. On very low-frequency sources like bass, fast attack combined with fast release can even create distortion because the compressor is trying to follow individual waveform cycles.

“The compression doesn’t seem to be doing anything”

Your attack might be too slow. If the attack time is longer than the transient itself, the compressor barely engages before the signal drops back below threshold. Try speeding the attack up gradually until you see consistent gain reduction on the meter.

If you’re running into other compression problems beyond attack time – pumping, muddiness, harsh vocals, unwanted noise – I put together a full diagnostic guide that covers nine common symptoms and the fix for each one: Why Does My Compression Sound Bad?

A Note on Compressor Types and Attack Behaviour

Not every compressor gives you the same control over attack time, and this matters.

An 1176-style FET compressor has a fixed fast attack. You can adjust it, but even at its slowest setting it’s still pretty quick. This is actually why engineers like Chris Lord-Alge love 1176s on drums – you get that fat, explosive, back-end-heavy sound that’s become a signature of rock mixing. It’s not about preserving the transient crack, it’s about emphasising the body and sustain.

That’s a deliberate aesthetic choice, and it’s especially effective in parallel – blend the smashed, saturated signal with your uncompressed transient and you get the best of both worlds. Just understand that if you’re reaching for an 1176 on a snare, you’re choosing a back-end sound. And if that’s what you want, it’s an incredible tool for it.

An LA-2A-style optical compressor doesn’t even have an attack control – it’s automatic and relatively slow. This makes it naturally transparent and musical, great for levelling things out without killing transients. But it’s not the tool for aggressive transient shaping.

A VCA compressor typically gives you full manual control over attack and release, which makes it the most flexible option for dialling in exactly the front end/back end balance you want.

Understanding this helps you choose the right compressor before you start tweaking settings. If you want punchy drums, reaching for an LA-2A and hoping for the best won’t get you there – not because it’s a bad compressor, but because it’s the wrong tool for that goal.

Try It Yourself

If you want to experiment with compressor attack time settings for different sources and goals, I built a free Compressor Calculator that gives you starting points based on what you’re compressing and what you’re trying to achieve. It won’t replace your ears – nothing does – but it’ll get you in the right ballpark so you’re not guessing from scratch every time.

Select your source, select your goal, and it’ll suggest attack time, release, ratio, and compressor type. Then tweak from there based on what you’re hearing.

If you want to see what’s happening, try the Compression Visualiser – it shows how different attack time settings shape the transient in real time. Sometimes seeing it makes the concept click in a way that reading about it can’t.

The Difference Between Knowing and Hearing

Here’s the thing though – and I’m being honest with you here. Reading about compressor attack time is useful. It gives you the conceptual framework. But there’s a gap between understanding what attack time does and actually hearing it in your mixes.

It’s like learning guitar. I can tell you this is a C chord, this is a G chord, here’s the shape, here’s the fret. But until you pick up the guitar and play it yourself, you’re never going to be able to play a song.

Compression is the same. The front end/back end framework gives you the map. But developing the ear to hear what’s happening and make decisions in real time? That takes practice. That takes mixing a lot of music, making mistakes, and paying attention to what works.

That’s exactly what I built The Compression Code to teach. Not a list of settings to memorise, but a framework for hearing compression and making decisions by ear – across any source, any genre, any compressor. If understanding attack time was your “aha” moment, the course is where you develop that into an actual skill.

If you found this useful, grab the free Compression Cheat Sheet – starting points for every common source and compression goal, in a printable PDF you can keep next to your DAW. I’ll also send you first access when new articles and tools drop.