Attack and release on a FET compressor, explained by ear

Load a snare, set the ratio to 4 and turn ATTACK slowly from 1 to 7. Somewhere around the middle the crack of the stick disappears. That moment is what this article is about. Attack sets how quickly the compressor clamps down after the signal gets loud, and release sets how quickly it lets go. Slow attack keeps the front of each hit, fast attack shaves it off. Fast release adds energy and grit, slow release smooths things out. On a FET compressor both happen in milliseconds or less, which is why small turns change so much.

What the two knobs do

Every compressor watches the level of the signal. When it goes over the threshold, the compressor turns the volume down, and when it falls back, the compressor turns the volume up again. Attack is the time the first move takes. Release is the time the second move takes.

On most compressors those times run from a few milliseconds to a second. A FET design is different: its attack starts at 20 microseconds and its slowest setting is still under a millisecond (only the AE revision adds a separate slow setting of about 30 ms). That is fast enough to catch the very first wave of a snare hit, so the attack knob decides how much of the transient survives.

Why the knobs run backwards

On classic FET compressors, and on PINCH-76, both knobs get faster as you turn them clockwise. ATTACK 7 is the fastest, ATTACK 1 the slowest. RELEASE works the same way. If a setting sounds too squashed, turn the knob to the left, not to the right.

Attack by ear

• Slow (1 to 2): the first few milliseconds of each note pass through untouched. Drums keep their crack and can even sound punchier than before, because the body is turned down while the front is not.
• Middle (3 to 5): the usual place for vocals and bass (full settings in how to compress vocals and how to compress bass). Peaks are held, but the voice still sounds open.
• Fast (6 to 7): the transient is shaved off. Good for taming a spiky vocal or an over-plucked bass, and for room mics where you want the sound of the room, not the hit.

A quick way to hear it: loop a drum bar, set about 6 dB of gain reduction, and sweep ATTACK from 1 to 7. Listen for the moment the snare loses its front edge. Usually the right setting is one step slower than that.

Release by ear

• Fast (6 to 7): gain comes back almost at once. The compressor follows the waveform closely and adds energy, density and some distortion. Great for aggressive drums and rap vocals.
• Middle (3 to 5): the safe choice on most sources. Release moves with the tempo instead of against it.
• Slow (1 to 2): gain comes back gently. Smooth, steady and controlled, good on the mix bus and on sustained parts.

PINCH-76's release is program dependent, like the hardware it models: after a short hit it recovers quickly, after long, heavy gain reduction it recovers more slowly. That is why a fast release can still sound natural on a full mix.

Matching release to the groove

If the meter needle is still on its way back when the next beat arrives, the release is too slow for the tempo and the track will sound flat. If the needle snaps back between every note and the sound seems to breathe in and out, it is too fast. Aim for the needle to settle just before the next important hit.

A useful reference is the release time each knob position shows in its value balloon. After long, heavy compression the program-dependent release stretches these several times over.

RELEASE	1	2	3	4	5	6	7
Time shown	1.1 s	660 ms	390 ms	235 ms	140 ms	85 ms	50 ms

At 120 BPM an eighth note lasts 250 ms and a sixteenth 125 ms. So RELEASE 4 recovers in about an eighth note and RELEASE 5 in about a sixteenth: a good place to start on drums at that tempo.

Settings to start from

Source	Revision	Ratio	Attack	Release	Gain reduction
Lead vocal	Rev D (LN)	4	3	5	3 to 6 dB
Snare	Rev F	8	3	6	4 to 8 dB
Kick	Rev D (LN)	4	2	6	3 to 6 dB
Bass	Rev D (LN)	8	4	3	3 to 6 dB
Room mics	Rev A	All buttons	6	7	8 dB or more
Mix bus	Rev D (LN)	4	1	5	1 to 2 dB

These are the factory start presets in PINCH-76 (Vocal Start, Snare Smack, Kick Grab, Bass Lock, Room Crunch and Bus Glue), so you can load them and adjust from there.