Mastering Compression Settings Explained
Published · updated · by Loopin
Mastering compression is subtle glue, not loudness. A low ratio, a slow-ish attack and only about 1–2 dB of gain reduction make a mix feel like one cohesive record. Here are the settings that work, what each control does on a full mix, and when multiband compression earns its place.
The goal is cohesion, not loudness
It’s a common mistake to treat the mastering compressor as a loudness tool — that job belongs to the limiter at the end of the chain. Bus compression here does something more delicate: it glues the elements of a finished mix so they move together and feel like a single, intentional record.
That means restraint. You’re aiming for cohesion your ear feels rather than gain reduction it notices. If the compressor is obviously working, it’s working too hard.
Ratio: keep it low (about 1.5:1 to 2:1)
Mastering bus compression uses a low ratio, roughly 1.5:1 to 2:1. That’s gentle by design — you’re nudging the loud moments closer to the quiet ones, not clamping the signal.
Ratio sets how firmly the compressor pushes back once the signal crosses the threshold. At 2:1, for every 2 dB the input rises above threshold the output only rises 1 dB — a soft, almost transparent squeeze. That gentleness is exactly what you want on a finished mix.
Higher ratios belong on individual tracks in the mix, where you might want to seriously control a wild vocal or an inconsistent bass. On a full master, a high ratio squashes the life out of the record and turns cohesion into flatness.
Attack: slow-ish, let transients through
Use a slow-ish attack so the compressor lets transients through before it clamps down. Those transients — the snap of the snare, the pluck of a string, the front of a vocal consonant — are what give a master punch and clarity.
The attack time controls how quickly the compressor reacts once the threshold is crossed. A fast attack catches the very front of every hit; a slower attack waves the transient through and only acts on the body of the sound behind it. On a master you almost always want the latter.
Grab the transients too fast and the master goes dull and lifeless, with all the impact rounded off. A slower attack preserves that impact while the compressor still smooths the sustained energy underneath.
Release: auto or medium
An auto or medium release is the safe, musical choice on a full mix. Auto release adapts to the material in real time and is very forgiving; a medium manual release lets the compressor recover between transients without pumping.
Release sets how fast the compressor lets go once the signal drops back below threshold. Get it roughly in time with the track’s pulse and the compression “breathes” with the music instead of fighting it.
Too fast and you get audible distortion and pumping as the gain jumps around; too slow and the compressor never fully lets go, quietly dragging the level down. If in doubt, auto release is genuinely hard to get wrong on a master.
Gain reduction: only about 1–2 dB
This is the number that matters most: aim for only about 1–2 dB of gain reduction on the mastering bus. That’s enough to bind the mix together without flattening its dynamics.
Watch the gain-reduction meter, not just your ears in the excitement of a loud playback. If the needle is pulling 4, 6 or more dB, you’re over-compressing — back off the threshold. Do not over-compress; you can’t undo squashed dynamics later in the chain.
Over-compression hides behind loudness — a squashed master can sound impressive for a few seconds before the flatness sets in. The tells: the mix sounds smaller and more distant rather than tighter, the drums lose their snap, you hear pumping as the compressor grabs and releases, and loud and quiet sections start to feel the same. If any of those appear, raise the threshold until the meter drops back toward 1–2 dB.
Multiband compression: target one problem band
Broadband glue treats the whole mix at once. Multiband compression splits the signal into frequency bands and compresses them independently — useful when one region misbehaves while the rest of the track is fine.
The classic case is an unruly low end: a multiband band can tame the bass and sub independently, keeping it steady and controlled without touching the mids and highs. Used surgically it fixes a specific problem; used heavily it over-processes the record, so keep the reduction gentle here too.
This is exactly why Loopin’s mastering chain keeps its bass band independent and mono — the low end is where uncontrolled energy does the most damage to a limiter, so controlling it on its own band lets the rest of the mix stay open and dynamic.
A safe starting point
If you’re dialling a mastering compressor by hand, start conservative and add only if it helps:
- Set the ratio low — 1.5:1 to 2:1.
- Choose a slow-ish attack so transients pass through.
- Set release to auto or medium.
- Lower the threshold until the meter shows just 1–2 dB of gain reduction.
- Add multiband only for a specific band that misbehaves, like an unruly low end.
- Rather not dial it by hand? Run the mix through Loopin’s free online mastering and let its gentle multiband glue do this stage automatically.
- A/B against the original at matched loudness — it should sound tighter and more together, not smaller.
Let the glue happen automatically
If you’d rather not chase attack and threshold settings, Loopin’s free online mastering handles this stage for you — gentle multiband compression that glues the mix while keeping the bass band independent and mono, so the low end stays controlled without squashing everything else.
It’s all in your browser with nothing uploaded: free, no signup, no watermark, full-quality WAV export. Run your mix through it and hear cohesive, un-squashed compression done for you.
Frequently asked questions
What compression settings should I use for mastering?
A low ratio (about 1.5:1 to 2:1), a slow-ish attack so transients pass through, an auto or medium release, and only about 1–2 dB of gain reduction. The goal is cohesion and glue, not loudness or squashing.
How much gain reduction is right when mastering?
Only about 1–2 dB on the mastering bus. That’s enough to bind the mix together without flattening its dynamics. If the meter is pulling 4–6 dB or more, you’re over-compressing — raise the threshold.
Why use a slow attack in mastering compression?
A slow-ish attack lets transients — the snap of the snare, the front of a vocal — through before the compressor clamps down. Those transients give a master its punch and clarity; grabbing them too fast makes the master dull and lifeless.
What is multiband compression used for in mastering?
It splits the signal into frequency bands and compresses them independently, so you can fix one region without touching the rest. The classic use is taming an unruly low end while leaving the mids and highs alone. Keep the reduction gentle.
Can I master without setting up a compressor?
Yes. Loopin’s free online mastering applies gentle multiband glue automatically, with the bass band kept independent and mono, in your browser with nothing uploaded — free and without a watermark.