mixing

Compression, part 3

Multiband Compression

Splitting the Signal again

This diagram visualizes how a multiband compressor works internally. The input signal is first split into separate frequency bands — typically low, mid, and high — using a crossover filter.

Each band then follows the same basic structure: The signal is split again into two parts:

  • One goes to the threshold detection (control path),
  • The other continues through the audio path.
  • The threshold control influences a gain reduction stage.
  • After that, make-up gain brings each band back to the desired level.
  • Finally, the processed bands are summed back together into one unified output.

Unlike a regular compressor, which treats the entire frequency range the same way, a multiband compressor allows precise control over each range — giving you much more flexibility.

graph LR Input[Input Signal] --> Xover[Crossover / Band Split] %% Band paths Xover --> LPath[Low Band Split] Xover --> MPath[Mid Band Split] Xover --> HPath[High Band Split] %% Low Band split LPath --> LAudio[Low Audio Path] LPath --> LThresh[Low Threshold Detection] LThresh -->|controls| LGR{Low Gain Reduction} LAudio --> LGR LGR --> LGain{Low Make-Up Gain} %% Mid Band split MPath --> MAudio[Mid Audio Path] MPath --> MThresh[Mid Threshold Detection] MThresh -->|controls| MGR{Mid Gain Reduction} MAudio --> MGR MGR --> MGain{Mid Make-Up Gain} %% High Band split HPath --> HAudio[High Audio Path] HPath --> HThresh[High Threshold Detection] HThresh -->|controls| HGR{High Gain Reduction} HAudio --> HGR HGR --> HGain{High Make-Up Gain} %% Recombine LGain --> Mix[Band Recombination / Summing] MGain --> Mix HGain --> Mix Mix --> Output[Output Signal]

When to Use a Multiband Compressor

Multiband compressors are especially useful when only part of the frequency spectrum needs control, or when different ranges behave differently. Here are a few use cases:

Master Bus Compression

On a full mix, a multiband compressor can gently tame harsh highs or overly boomy lows without affecting the punch of the mids. This gives your mix polish and control without flattening everything.

suggested settings

Band Frequency Range Threshold Attack Release Notes
Low 20 – 120 Hz –3 to –5 dB 30 ms 100 ms Gently tame sub rumble
Mid 120 – 4 kHz –2 to –4 dB 20 ms 80 ms Control body without killing punch
High 4 kHz – 20 kHz –2 to –4 dB 5–10 ms 60 ms Smooth out harshness

Tips: Use low ratios (2:1), aim for subtle “glue,” avoid over-compression.

Reese Bassline (or any sound with rich harmonics)

When working with a Reese bass or other harmonically complex sounds, the low sub might be stable, but the mids and highs might jump all over the place. A multiband compressor lets you leave the sub untouched while tightly controlling the wild midrange growl.

suggested settings

Band Frequency Range Threshold Attack Release Notes
Low 20 – 100 Hz –1 to –3 dB 50 ms 120 ms Let the sub breathe
Mid 100 – 2.5 kHz –6 to –10 dB 10 ms 80 ms Aggressively control growl
High 2.5 kHz – 12 kHz –4 to –6 dB 5 ms 50 ms Tame harsh top-end movement

Tips: Use high ratios (4:1 to 6:1) on the mid band; leave low band mostly untouched.

Drum Group

Drums contain energy across the spectrum: Kick = low end Snare = mids Cymbals = highs A multiband compressor helps you tighten just the low end or tame splashy highs without squashing the whole drum group’s punch and groove.

suggested settings

Band Frequency Range Threshold Attack Release Notes
Low 20 – 150 Hz –4 to –6 dB 25 ms 120 ms Control kick body
Mid 150 – 4 kHz –3 to –5 dB 10–20 ms 100 ms Shape snare/transients
High 4 kHz – 16 kHz –4 to –6 dB 5–10 ms 80 ms Tame cymbals/hi-hats

Tips: Use longer attack to preserve punch. Try parallel compression for thick but airy drums.

Vocals

Vocalists often have uneven energy in specific bands, like:

Harsh sibilance in the highs (around 5–8 kHz)

Mud in the low-mids With multiband compression, you can de-ess, control chest resonance, or balance nasality without using multiple plugins.

suggested settings

Band Frequency Range Threshold Attack Release Notes
Low-Mid 100 – 300 Hz –3 to –5 dB 10 ms 80 ms Clean up muddiness
Mid 300 Hz – 4 kHz –4 to –6 dB 5 ms 100 ms Control body/nasality
High (De-Ess) 4 kHz – 9 kHz –5 to –10 dB 2–5 ms 60 ms Smooth sibilants (de-essing)

Tips: Use high ratio (6:1+) for sibilance. Short release avoids pumping artifacts.

Video Tutorial

Here is a great video tutorial which demonstrates some of these use cases: