The kick and the bass are fighting over the same 60 Hz, and one of them has to move. That is the whole problem sidechain compression solves, and it is the technique I reach for before I reach for EQ. Cutting the bass everywhere to let the kick through leaves the low end thin between hits. Ducking the bass only when the kick fires keeps the weight and clears the transient at the same time.
This is a walkthrough of how I actually set it up on a house track, from routing to the release time that stops the pumping from choking itself.
Start with the sidechain source, not the compressor
Most bad sidechain sounds I hear are a triggering problem, not a settings problem. The compressor is being told to duck by a kick that it can barely read.
A raw kick can confuse the detector if it carries a lot of sub content, because the sub is smeared and slow to resolve. A high-passed copy of the kick triggers more cleanly. I usually keep a duplicate of the kick channel, high-pass it, and route that to the sidechain input. The detector now reacts to the click and the body, not the rumble.
When the kick is very dynamic, the cleaner fix is a dedicated trigger track. A short click or pulse lined up with every kick gives the compressor a consistent signal regardless of how hard the drummer or the sample hit. That matters less for a four-on-the-floor house pattern than for a live break, but it is the difference between even pumping and a ducking curve that jerks around.
If your DAW offers MIDI-triggered sidechain, use it. The compressor responds to notes instead of audio, so there are no false triggers and the timing is exact. I reach for it when the kick pattern is complex or when I have already committed the kick to audio and do not want to think about detection at all.
Attack: fast enough to clear, slow enough to not click
The attack decides how quickly the bass gets out of the way after the kick lands. Back it off and the low end swallows the kick’s front edge, which is exactly the thing you were trying to protect. Somewhere in the 1 to 5 ms range gets the bass down fast enough for the kick to speak.
Drive it past the sweet spot and the low end starts pumping in steps. That click is the compressor slamming the gain down in one sample. If it shows up, back the attack off to around 5 to 10 ms. You still duck in time for the kick to read; you just smooth the edge so it does not sound like a gate.
The right number is material-dependent. I set it by ear every time, because the transient shape of the kick and the pitch of the bass both change how obvious the jump is.
Release: the one that actually makes or breaks the groove
This is where most pumping low end goes wrong. The release has to finish before the next kick hits. If it does not, the ducking accumulates, the bass never fully comes back, and you end up with a bass that is permanently squashed and a kick that still is not clean.
At tempos around the 120 mark, a 100 to 200 ms window is a solid place to start. Push the tempo and you shorten it, closer to 50 to 100 ms. Think about how much time sits between kicks in your pattern and set the release to fit inside it with a little margin.
Many modern compressors ship with auto-release. In sidechain use it often lands somewhere musical without you doing the math. I still check it by ear, because auto-release is guessing at the pattern and I already know it.
How much ducking: 2 to 4 dB or 6 to 10 dB
Ratio and threshold together set the depth. This is a style decision more than a technical one.
- 2 to 4 dB of reduction gives separation you feel but do not hear. The bass and kick read as two clean elements. Good for the more musical end of house where the bassline carries the track.
- 6 to 10 dB or more gives the obvious pumping that is part of the sound in dance music. Here the breathing is the groove, not an artifact to hide.
Threshold sets what triggers the ducking. Lower, and ghost notes and soft kicks pull the bass down too. Higher, and only the loudest hits move it. Set the threshold to match how the kick actually plays, not to a number you read somewhere.
When one band is not enough
Full-range ducking pulls the entire low end under, definition harmonics and all. Multiband sidechain lets you duck only the sub that collides with the kick and leave the upper bass untouched. The low band dips hard; the bands above it stay put. You keep the attack and clarity of the bass while still clearing the sub.
There is also frequency-conscious ducking, where the plugin works out which frequencies the kick occupies and carves the low end just in that pocket. Ask around and Trackspacer is the name that keeps coming up. It is less predictable than a fixed multiband setup, but on a busy low end it can feel like someone did the carving for you.
One rule I hold to: keep the low end to one bass and one kick, and keep the other instruments out of that range entirely. Sidechain only fixes the overlap between two sources. If a pad or a low synth is also sitting on the same fundamental, ducking the bass will not save you. That is a problem of arrangement, not level, and no compressor setting solves it.
Check the result against the groove, not the meter
After the settings are in, I mute the trigger and listen to the bass alone. The ducking should trace the kick pattern, and the bass should have recovered before the next hit. Then I bring the kick back and check whether the two lock into a single pumping gesture or still sound like two tracks that happen to overlap.
If the bass comes back too slow and the groove sags, shorten the release. If it feels choppy, ease the attack and pull the depth back a couple of dB. The compressor is there to make the kick and the bass take turns, not to flatten the bass.
The best result is the one where you cannot tell compression is happening, just that the low end has room and still hits. When it locks, stop touching it.