What is multiband compression, and when should you use it?

Multiband compressors split your input signal into multiple frequency bands — typically between three and five, but sometimes more — passing each through its own compressor before mixing the results back together for output.

READ MORE: ‘What does a compressor do in music?’: A beginner’s guide to compression

In most examples of the breed, each band’s compressor will be full-featured, offering the familiar compression settings: threshold, ratio, attack, release, and make-up and/or output gain.

Why use a multiband compressor?

Conventional compressors tend not to work well on sources that contain a wide range of frequencies – a full mix, a drum kit submix, synths, pianos, for example. The problem is that low-frequency elements like kick drums and basses contain more energy than higher-frequency sounds, and so are more likely to exceed the compression threshold, thereby triggering the compressor. However, the resulting compression impacts the entire mix and can cause an audible pumping effect that’s only useful as a special effect.

Sidechain filtering can help, but it’s not as good a solution as multiband compression. By tackling each frequency range independently, you can set thresholds, ratios and more to suit the sounds within that range without impacting the dynamics of the other bands. This makes multiband compression far more sonically transparent than broadband compression, even while delivering stronger compression.

The ability to control the output level of each band also gives multiband compressors a secondary role as a sort of broad-brushed EQ that isn’t centred around specific point frequencies.Learn more audio and music production terms in our Glossary

When should I use a multiband compressor?

As already alluded to, multiband compressors are at their best when used on sources containing a wide range of frequencies. Because of this, they’re regularly applied to the master bus during mixing, and almost always deployed during mastering. In this role, they can bring cohesion (sometimes referred to as ‘glue’) and solidity to a mix/master.

A common approach here is to apply stronger compression to the low band(s) to create a solid and consistent grounding, medium compression to the mid band(s) to pull things together but still allow some dynamic movement and variation, and only light compression in the upper bands to keep things sounding airy and free… of course, sometimes the exact opposite setup works well too!

The inherent sonic transparency of multiband compression compared to broadband compression, and the ability to tune band frequency ranges to suit any source, makes multiband compression useful on individual instruments and parts too.

Put simply, anything a broadband compressor can do, a multiband compressor can normally do better — with a little more setup.

Examples of Multiband Compressors

SSL G3 MultiBusComp: Combines three SSL G-series compressors in a single multiband processor, with per-band wet/dry mix and per-band external sidechain input.

PSP OldTimer MB: Multiband version of PSP’s OldTimer compressor, itself inspired by vintage tube compressors. Includes per-band stereo width control.

Your DAW: Many DAWs come with a multiband compressor included in their bundled plugin suite. This may lack the character of a premium option, but will certainly do the job.

Learn more audio and music production terms in our Glossary

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