Apex: a multiband compressor plugin for upward and downward compression

What a multiband compressor does

A multiband compressor splits a sound into frequency bands and compresses each band on its own. A normal compressor turns the whole signal down when anything gets loud, so a booming bass note also ducks the vocal or the hi-hats. With multiband compression, the low band can be held in place while the mids and highs stay open.

Apex uses three bands. The Low/Mid crossover (40 Hz to 1 kHz, default 120 Hz) and the Mid/High crossover (1 to 10 kHz, default 2.5 kHz) set where they split. Each band has its own downward amount, upward amount and gain, and per-band meters show how hard each one is working. For the theory in more depth, read what a multiband compressor is.

Upward vs downward compression

Downward compression turns loud parts down, which is what most people mean by compression. Upward compression turns quiet parts up: reverb tails, breaths, the decay of a synth note, the room sound on a drum. Doing both at once squeezes the dynamic range from both ends, which is the dense, hyper-detailed sound OTT-style processing is known for.

Full Smash runs everything at full Depth. On the demo you'll hear tails and quiet notes jump forward until the sound feels pressed against the speakers. Pull Depth back to 30% and it becomes useful on a mix rather than an effect.

How to use a multiband compressor

Start with one knob, then refine. Most of the time you only need Depth, Time and Mix.

1. Pick a preset close to the job, or start at Default (Depth 60%).
2. Set Depth by ear. It scales all six compression amounts together, from 0 (off) to full smash, so you never have to chase thresholds.
3. Set Time for the material. Lower values react faster and pump more; Drum Bus Pump sits at 25%. Higher values are smoother; Mastering Light uses 70%.
4. Move the crossovers only if a band is catching the wrong thing. Lowering Low/Mid to 90 Hz, as Bass Control does, keeps the low band on the sub and leaves the bass's growl in the mid band.
5. Use Low Gain, Mid Gain and High Gain (±12 dB) to rebalance after compression, then Mix to blend back some of the dry signal. 50 to 70% Mix keeps transients while adding density.
6. Match the Output level to the bypassed sound before you decide it sounds better.

Multiband compression presets for synths, vocals, drums and bass

Gentle Glue is the opposite of Full Smash. On the demo it barely changes the sound at first; listen to the quiet notes between hits and you'll notice they hold together more evenly, without any obvious squash.

Multiband compression on bass

Bass is where multiband compression earns its place. Low notes carry far more energy than high ones, so a normal bass compressor clamps down on every low E and lets the higher notes through untouched. Compress the low band alone and the sub level stays even across the whole bassline, while the mid band keeps the pick, growl or synth character moving freely. Start from Bass Control, play the lowest and highest notes of the part, and watch the Low meter: it should move on the low notes and stay nearly still on the high ones.

Multiband compression for mastering

On a master, multiband compression should be close to inaudible. Use Mastering Light as a ceiling, not a starting point to push from: Depth around 10 to 20%, slow Time and Mix around 70%. The goal is to stop one band from jumping out (harsh hi-hats in a chorus, a bass note that blooms) without changing the balance the mix engineer set. If you need peak control for loudness, that is a limiter's job; compressor vs limiter explains the difference.

Style: from bus glue to OTT in one knob

Depth sets how hard Apex works. Style sets what kind of compressor it is. At 0 it behaves like gentle bus glue, around 40 it turns punchy, at 70 (the default) it is classic OTT-style compression, and at 100 it is hyper OTT for the most detailed, aggressive sound. You can move between those characters without resetting thresholds or band amounts.

Heavy OTT-style settings usually flatten transients, which is why drums lose their hit. Per-band Punch fixes that: Low Punch lets kick and bass attacks through before the low band clamps down, Mid Punch does the same for snares and vocal consonants, and High Punch for hats and pick attacks. Transient Keeper sets all three to 100% at 80% Depth, so you get the density without losing the front of each hit. Punchy Drums uses Low Punch at 60% and Mid Punch at 70% with Style at 40.

Using Apex in Ableton Live, FL Studio and Pro Tools

Apex works as an insert on a track or bus. On synths and vocals, put it after EQ and before reverb, so it doesn't lift the reverb tail into a wash. On a drum bus or the master, put it near the end of the chain, before the limiter.

• Ableton Live: drag Apex from the Plugins section of the browser onto the track or Group track. It does the same job as Live's Multiband Dynamics, with per-band upward and downward amounts and one Depth control. Our Ableton page covers installation.
• FL Studio: load Apex in an effect slot on the Mixer insert. It covers the same ground as Fruity Multiband Compressor and adds upward compression.
• Pro Tools: insert Apex (AAX) on the track or on an Aux Input you use as a bus.
• Logic Pro: load the AU version in an Audio FX slot on the channel strip or a Summing Stack.