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7.1.2 Compressor

Evens out the level of a track: tames loud peaks, brings up quiet detail and makes vocals, bass and drums sit steadily in the mix.

Harmonic Pro Studio Lite Compressor plugin

A compressor turns a sound down when it gets louder than a level you choose. The loud parts come down, the quiet parts stay where they are, and the track becomes more even. Use it to keep a vocal steady, stop a bass line jumping out on some notes, add punch to drums, or glue a group of sounds together.

7.1.2.1 Adding the Compressor

  1. Select the track.
  2. Right-click the Plugin Editor and choose Add Lite Plugin ▸ Compressor.
  3. Make sure its power button is on (orange).
  4. Play the track, then set THRESH and RATIO (see Quick start).

Unlike the Gate, the Compressor starts working as soon as it is switched on. See Lite effects for how the rack works.

7.1.2.2 The window

  • Title bar: the drag dots (to move the Compressor in the rack), the power button, the name, and on the right GR: how much the Compressor is turning the sound down right now, in dB. It reads OFF when the power is off.
  • Display: a picture of what the Compressor does. The level going in runs from left to right and the level coming out from bottom to top, both from −60 to 0 dB.
    • The dashed diagonal line is “no change”: out equals in.
    • The orange line is your setting. It follows the diagonal up to the threshold, then bends and rises more slowly. The flatter it gets after the bend, the stronger the compression. MAKEUP moves the whole line up or down.
    • The faint vertical line marks the threshold.
    • The white dot shows the level of your track as it plays, riding on the orange line.
    Click or drag left and right inside the display to set the threshold.
  • Under the display: GR again, with the current gain reduction in dB.
  • Knobs: THRESH, RATIO and MAKEUP on the top row; ATTACK and RELEASE below.

7.1.2.3 Controls

ControlRangeDefaultWhat it does
THRESH−60 to 0 dB−18 dBThe level where compression begins. Sound below it passes unchanged; sound above it is turned down. The lower the threshold, the more of your track is compressed.
RATIO1:1 to 20:14:1How strongly sound above the threshold is turned down. At 4:1, a sound that goes 8 dB over the threshold comes out only 2 dB over. At 1:1 nothing happens; near 20:1 the Compressor acts almost like a limiter.
MAKEUP−12 to +12 dB0 dBTurns the whole output up or down after compression. Use it to bring the level back to where it was before you compressed.
ATTACK0.1 to 100 ms10 msHow quickly the Compressor reacts once the sound goes over the threshold. Short catches every peak; longer lets the start of each hit or note through before it clamps down, which keeps punch.
RELEASE5 ms to 2 s120 msHow quickly the Compressor lets go once the sound falls back under the threshold. Short is lively but can make the level wobble; longer is smoother but can hold the sound down for too long.
Watch GR. Usually a few dB of gain reduction on the loudest parts is plenty. If GR hardly ever returns to 0, the Compressor is working all the time and the track may start to sound flat.

7.1.2.4 Quick start

  1. Leave RATIO at 4:1, ATTACK at 10 ms and RELEASE at 120 ms.
  2. Play the track and lower THRESH (or drag in the display) until the white dot goes past the bend on the loudest parts and GR shows around −3 to −6 dB.
  3. Raise MAKEUP by about the same amount, so the track is as loud as it was with the Compressor off. Switch the power off and on to compare.
  4. Too much? Raise THRESH or lower RATIO. Lost its punch? Lengthen ATTACK. Pumping or wobbling? Lengthen RELEASE.

7.1.2.5 Good to know

  • Smooth bend. Compression eases in gently around the threshold rather than switching on suddenly, so it stays natural even at high ratios.
  • Stereo stays put. Both sides are turned down together, so a stereo sound doesn’t shift from side to side as the Compressor works.
  • No delay. The Compressor adds no latency to your track.
  • Level is up to you. MAKEUP is not set for you. Compare with the power off at the same loudness, because louder almost always sounds “better”.
  • Off means locked. While the power is off, the knobs and display don’t respond. Turn the power on to make changes.
  • Knobs. Drag up or down to turn a knob, hold Shift as you start the drag for fine steps, and double-click a knob to reset it.
  • Automation. Right-click any knob to automate it.

7.1.2.6 Recipes

Steady vocal

RATIO 3:1 to 4:1, ATTACK 5–15 ms, RELEASE 80–150 ms, THRESH so GR reaches −3 to −6 dB on the loud words. Bring the level back with MAKEUP.

Even bass line

RATIO 4:1, ATTACK 10–30 ms, RELEASE 100–200 ms, THRESH so every note shows a little GR. Notes stop jumping out and the low end stays solid.

Punchy drums

RATIO 4:1 to 6:1, ATTACK 20–40 ms so the hit gets through first, RELEASE 50–100 ms so the Compressor lets go before the next hit.

Gentle glue on a group

RATIO 2:1, ATTACK 20–30 ms, RELEASE 150–300 ms, THRESH so GR only moves 1–2 dB. The parts sound more like one performance.

Catch the odd peak

RATIO 10:1 to 20:1, ATTACK 0.1–1 ms, RELEASE 50–100 ms, THRESH just under the loudest peaks. Only the peaks are touched. For a hard ceiling at the end of a chain, use the Limiter.

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