Explainer
What Is a Multiband Compressor? How Multiband Compression Works and How to Use It
Updated 5 min read
A multiband compressor is a compressor that splits audio into several frequency bands, usually lows, mids and highs, and compresses each band independently. That lets you control a booming low end or a harsh top without squashing everything else in the signal.
It's one of the most useful tools in mixing and mastering, and one of the easiest to overdo. Here's how it works, what it's good for and how to set one up without wrecking the tone.
How does a multiband compressor work?
A normal compressor turns the whole signal down when it gets loud. If a bass note booms, the vocal and the cymbals get turned down with it. A multiband compressor avoids that in three stages.
- Crossover filters split the signal. Two crossover points give you three bands: everything below the first point, everything between the two, and everything above the second.
- Each band gets its own compressor. Threshold, ratio, attack, release and gain can be set separately per band, so the lows can be held steady while the highs are left open.
- The bands are summed back together. Good crossovers, such as Linkwitz-Riley filters, add back up flat when no compression is happening, so the plugin is transparent until it starts working.
If compression itself is new to you, start with our compressor vs limiter guide, which covers threshold, ratio, attack and release.
Upward and downward compression
Most compressors work downward: when a signal goes over the threshold, it gets turned down. Some multiband compressors also work upward: when a signal falls below a threshold, it gets turned up. Combine both and quiet detail rises while loud peaks fall, so each band ends up dense and even.
That combination on three bands is the sound Xfer Records' free OTT plugin made famous in electronic music: hyper-detailed synths, crispy hats and reverb tails pulled right up into the mix. Apex works in the same way, with separate downward and upward amounts on each of its three bands and a single Depth knob that scales the whole effect.
When to use multiband compression
Bass notes that boom louder than others
- Band to work on
- Lows, roughly below 120 to 200 Hz
- What to do
- Downward compression with a medium attack
Vocal that turns harsh only on loud notes
- Band to work on
- Upper mids, roughly 2 to 5 kHz
- What to do
- Downward compression with a fast attack
Sibilance
- Band to work on
- Highs, above about 5 kHz
- What to do
- Fast compression on the top band, or a de-esser
Synth or pad lacking detail
- Band to work on
- Mids and highs
- What to do
- Upward compression to lift quiet texture
Mix bus low end swelling in the chorus
- Band to work on
- Lows
- What to do
- Gentle downward compression, 1 to 2 dB
Drum bus lacking energy
- Band to work on
- All three
- What to do
- Upward compression blended in with the mix control
A useful rule: if the problem is always there, use EQ. If it comes and goes, use dynamics. A bass that's boomy on every note just needs a cut, which our EQ guide covers. A bass that's boomy only on two notes is a job for multiband compression.
How to use a multiband compressor
- Name the problem first. "The low end jumps in the chorus" is a reason to reach for multiband. "It should sound better" is not.
- Set the crossovers around the problem. If the boom is around 100 Hz, put the low crossover above it, say 150 to 200 Hz, so the low band contains the problem and little else.
- Work one band at a time. Solo the band if your plugin allows it, set the threshold so it only reacts when the problem appears, and use moderate ratios.
- Keep gain reduction small. On a mix or master, 1 to 3 dB per band is usually plenty. Heavier settings belong on individual sounds where you want an obvious effect.
- Watch attack and release. Fast attacks on the low band can distort bass by acting within a single waveform cycle. Start slower on the lows and faster on the highs.
- Level-match and compare. Multiband compression changes tone, so set the output to match the bypassed level before you judge it.
Here's the gentle end of the scale. Apex's Gentle Glue preset sets Depth to 25% and Time to 60%, with the upward amount on each band at 30%. It evens out the loop without any obvious squashing.
Style
Low
20–120 HzMid
120–2.5k HzHigh
2.5k–20k HzI/O
dBFSThe real plugin engine, running in your browser: same DSP code and presets as the VST3/AU/AAX.
And here's the other end. Full Smash sets Depth to 100% and Time to 40%, with every band's upward and downward amounts at full. Quiet details jump forward and everything sounds loud, bright and dense. It's a sound-design effect, not a mix fix.
Style
Low
20–120 HzMid
120–2.5k HzHigh
2.5k–20k HzI/O
dBFSThe real plugin engine, running in your browser: same DSP code and presets as the VST3/AU/AAX.
Multiband compression on vocals and bass
On a vocal, a multiband compressor is a precise fix for a voice that's fine at normal level but turns harsh or boomy when the singer pushes. Put a band around the harsh range, usually somewhere in the upper mids, and set it to react only on the loud notes. On bass, hold the lowest band steady so every note carries the same weight, while the upper band keeps the pick or growl that lets the bass be heard on small speakers.
What to look for in a multiband compressor plugin
- Clean crossovers that sum flat, so the plugin doesn't color the sound before it even compresses.
- Per-band meters showing gain reduction, so you can see which band is working and by how much.
- Adjustable crossover points. Fixed bands rarely line up with the problem you're trying to fix.
- A mix control for parallel blending, which keeps transients intact under heavy settings.
- Upward compression if you want the OTT-style detail effect, not just control.
Apex covers that list with three bands, crossovers adjustable from 40 Hz to 1 kHz (low/mid) and 1 to 10 kHz (mid/high), separate downward and upward amounts and gain per band, Time, input, output and mix controls.
Ableton multiband compressor: Multiband Dynamics
Ableton Live's multiband compressor is Multiband Dynamics. Each of its three bands has a threshold above and below, so it can compress downward and upward at the same time, and its OTT preset is where the OTT sound started. Solo a band, set the crossovers around the problem, and leave the bands that sound fine untouched. Apex does the same job with one Depth knob scaling all three bands.
Common multiband compression mistakes
- Using it as an EQ. If you're changing band gains a lot and barely compressing, an EQ will do it more cleanly.
- Compressing every band because it's there. Leave bands that don't have a problem untouched.
- Judging louder as better. Upward compression raises the average level. Match levels or you'll always prefer the processed version.
- Squashing the low band hard on a master. It robs the kick of punch. Small amounts and slower attack keep the transients alive.
FAQ
What is multiband compression?
Multiband compression splits a signal into frequency bands, typically three or four, and compresses each band separately with its own settings. A loud bass note only turns the low band down, so the vocal and cymbals above it stay put. It's compression that only acts on the part of the spectrum causing the problem.
How do you use a multiband compressor?
Start with every band bypassed or at zero. Find the range causing trouble, set the crossovers around it, then lower that band's threshold until it only reacts when the problem appears. Leave the other bands alone. Use small amounts of gain reduction and compare with bypass at matched levels.
When should you use a multiband compressor?
When a problem sits in one frequency range and comes and goes: a bass that booms on certain notes, a vocal that gets harsh only when it's loud, a mix whose low end swells in the chorus. If the problem is always there, a static EQ cut is simpler and usually sounds better.
Is a multiband compressor the same as a dynamic EQ?
They solve similar problems differently. A multiband compressor splits the signal with crossovers into adjacent bands that cover the whole spectrum. A dynamic EQ uses individual bell or shelf bands that only move when triggered, leaving everything else untouched. Dynamic EQ is often more surgical; multiband is better for broad control.
Should I use a multiband compressor on the master?
You can, but carefully. Small amounts can steady the low end or tame a harsh top on a finished mix. Heavy multiband compression on a master changes the mix balance in ways that are hard to hear in the moment, so it's usually better to fix problems on the tracks themselves first.