AUD · Audio tools

Audio Sidechain Compressor

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Settings are written to the URL as you change them. Nothing differs from the defaults yet.

Pull an audio file’s level down on a repeating pulse and let it recover, the ducking pattern usually heard under a kick drum in electronic music.

No sidechain input

A real sidechain compressor keys off a second track, most often a kick or a click. This tool has one file and one chain to run it through, so there is nothing external to key off. The pulse comes from an oscillator instead, set directly in hertz rather than detected from audio.

Rate and depth

Rate sets how often the duck repeats, from 0.5 Hz to 10 Hz. Depth sets how far the level drops at the bottom of each cycle, up to 30 dB.

Attack, release, and shape

Attack and release control how the reduction moves toward its target, the same ballistics a compressor uses. A fast attack with the square shape produces the sharp step-down and curved recovery of a classic pump. Slower attack and release settings soften the edges into something closer to a tremolo.

Sine and triangle shapes fall and rise smoothly across the whole cycle rather than stepping, which reads as modulation rather than ducking.

Example: a pump under a pad

Rate 2 Hz, depth 8 dB, attack 5 ms, release 250 ms, square.

Each pulse pulls the pad down fast and lets it climb back before the next one lands, leaving a gap that a kick would normally occupy even though no kick is present in the file.

Frequently Asked Questions

It pulls the level down on a repeating rhythmic pulse and lets it recover, the pumping effect usually produced by a compressor listening to a kick drum on a separate track. It reads WAV, MP3, M4A, AAC, Ogg, Opus, FLAC, AIFF, and WebM audio, and exports in the format the source arrived in.

There isn't one. A file passing through here is the only signal available, so the pulse comes from an oscillator running at the rate you set rather than from a second track's kick drum.

A hardware sidechain compressor reacts to a kick's sharp transient and then recovers, which the square shape reproduces: it steps down instantly on attack and eases back up on release. Sine and triangle fall and rise gradually instead, closer to tremolo than to ducking.

Divide the tempo by 60 for one duck per beat. At 128 BPM that is roughly 2.13 Hz. There is no tempo sync, so a track that changes speed will drift out of alignment with a fixed rate.

The Compressor tool reduces level in response to how loud the file already is. This one ignores the file's level entirely and reduces it on a fixed schedule, which is why it can produce a rhythmic pump on program material with no natural transients to trigger from.

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