You mixed the kick until it hit hard. You mixed the bass until it sat wide and warm. Solo either one and it sounds great. Play them together and the bottom of your mix turns into a shapeless rumble, your meters slam on every downbeat, and the limiter on the master starts working for a living. Nothing is technically wrong. The two loudest things in your song are simply trying to occupy the same forty hertz at the same instant.
Sidechain compression is the standard fix, and it is one of the few mixing moves that produces an instantly obvious improvement. This guide covers what ducking actually is, how to route it in every major DAW, how to set threshold, ratio, attack, and release so it works instead of just pumping, how to pick a release time from your tempo, and the six places it fixes a mix that have nothing to do with EDM.
You cannot judge low-end ducking on laptop speakers, phone speakers, or cheap earbuds, because none of them reproduce the 40–100 Hz range where this decision lives. You need monitors or a pair of full-range headphones. If you are still shopping, start with our guide to the best headphones for mixing or studio monitors for 2026.
What Sidechain Compression Actually Does
A normal compressor listens to the track it sits on. Signal gets loud, compressor turns it down. Simple feedback loop, one signal, one decision.
A sidechain compressor listens to a different signal. You feed it a second input (called the key input, sidechain input, or external input depending on your DAW) and the compressor uses that signal to decide when to reduce gain, while still processing the track it lives on. Put a compressor on your bass, feed the kick into its key input, and the bass gets turned down every time the kick hits. That is the entire idea.
The industry word for this is ducking: one element momentarily gets out of the way for another. When you set it gently, nobody hears the compressor working. They just hear a kick that punches through cleanly and a low end that stopped fighting itself. When you set it aggressively, the gain reduction becomes a rhythmic effect in its own right: the pumping, breathing sound that has driven house, techno, and festival EDM for three decades.
WHAT THE KICK DOES TO THE BASS
Time
Two things are worth separating in your head right away. Ducking is a level tool: it works in time, moment by moment. Carving with EQ is a frequency tool: it works permanently, whether the kick is playing or not. They solve overlapping problems and the best mixes use both, but they are not interchangeable, and reaching for the wrong one is why a lot of home-studio low ends stay muddy no matter how much EQ gets thrown at them.
Why Kick and Bass Fight for the Same Space
Look at a kick drum on a spectrum analyzer and you will usually find its body somewhere between 50 and 100 Hz, with a click of attack up in the 2–5 kHz range. Now look at a bass. Its fundamental notes live in almost exactly the same octave. An E1 on a five-string bass is about 41 Hz, and a typical sub-bass patch in a trap or house track sits between 40 and 80 Hz. Two of the loudest, highest-energy elements in your track are stacked in the narrowest, most fragile part of the frequency spectrum.
Two problems follow. The first is masking: when two sounds occupy the same frequency range and one is louder, your ear stops resolving the quieter one as a separate event. The kick stops sounding like a hit and starts sounding like a bump in the bass line. The second is summing: low frequencies carry the most energy in a mix, so when kick and bass peak simultaneously the combined level can jump several decibels. That single stacked peak is often what is triggering your limiter and eating the headroom you were saving for everything else. If peaks and headroom are still fuzzy, our guide to sample rate and bit depth covers what the meters are actually measuring.
You have three ways to respond. You can carve with EQ: dip the bass a few dB at the kick's fundamental and let the kick own that band. That works, but it is permanent: the bass is thinner even in the bars where the kick is not playing. You can arrange around it: write parts that do not land on the same beat, which is genuinely the most musical fix and costs nothing. Or you can duck: leave both parts full and let the bass step aside for the 100 or 200 milliseconds where the kick needs the room. Ducking is the only one of the three that is dynamic, and that is why it became the default.
Before you reach for any of them, check where your two elements actually overlap. Our Frequency Reference Chart shows the working ranges for kick, bass, and six other instruments side by side, so you can see whether you have a genuine collision at 60 Hz or a muddiness problem two octaves higher that ducking will not touch.
How to Set Up Sidechain Compression in Your DAW
The routing is the same idea everywhere, even though the menus differ. You are asking a compressor to listen to a track it is not on.
- Put a compressor on the bass track. This is the track that will be turned down.
- Open the compressor's sidechain or key-input section and choose the kick as the source.
- Set a fast attack, a moderate release, and pull the threshold down until the gain reduction meter moves.
- Watch the meter, not the knob. You are aiming for 3–6 dB of reduction on each kick for a transparent result.
HOW THE KICK IS ROUTED
- Kick track goes to the mix untouched
- A copy of it is tapped off as a trigger
- Key input of the compressor on the bass
- Bass ducks, then recovers
The key input listens. It does not pass audio through to the mix.
Where you find that key-input control depends on what you are running:
| DAW | Where the sidechain lives |
|---|---|
| Ableton Live | Compressor device → expand the arrow at top-left → enable Sidechain → pick the kick track from the Audio From menu. |
| Logic Pro | Compressor plugin → the Side Chain menu at the top right of the plugin header → choose the kick channel. |
| FL Studio | Right-click the kick channel's mixer send arrow to the bass insert → Sidechain to this track → then set the compressor's sidechain source to that number. |
| Studio One | Add a sidechain send from the kick channel → enable the Sidechain button in the compressor header on the bass. |
| Pro Tools | Send the kick to an internal bus → set that bus as the plugin's Key Input → engage the external key. |
| Reaper | Route the kick to channels 3/4 of the bass track → in the compressor, set the detector input to those channels. |
One habit worth building from day one: filter the key input. Most compressors offer a high-pass or band-pass on the sidechain listening path. If you are triggering from a full drum bus rather than an isolated kick, hi-hats and snares will fire the compressor too, and your bass will duck on every eighth note. Low-passing the sidechain at around 150 Hz makes the compressor deaf to everything but the low thump, which is exactly what you want it responding to. A high-pass would do the opposite: it would strip out the kick and leave the compressor listening to the hats.
The Controls That Shape the Duck
Four controls do almost all of the work, and understanding what each one changes turns this from preset-hunting into a decision you can make in ten seconds.
Threshold decides how much of the kick counts as a trigger. Set it too high and only the loudest kicks duck anything, which makes the effect inconsistent from bar to bar. Set it low and every kick (including ghost notes and velocity-varied hits) pulls the bass down by the same amount. For a tight, machine-like electronic track, low is right. For a live-feeling record where you want the drummer's dynamics to survive, leave it higher so quieter hits duck less.
Ratio decides how hard the duck is once the threshold is crossed. A 4:1 ratio gives you a gentle, invisible pocket. Push to 8:1 or 10:1 and the movement becomes audible, which is the point in dance music. If ratios still feel abstract, our explainer on compression ratios walks through what each number actually does to a signal.
Attack decides how fast the bass gets out of the way, and this is the one most people set wrong. A very fast attack (0–3 ms) clamps the bass down before the kick's transient arrives, giving you maximum separation and the classic pumping shape. A slower attack (10–20 ms) lets the first few milliseconds of bass through underneath the kick's attack, which keeps the low end feeling connected and full instead of hollow. Fast for electronic, slower for anything you want to feel played.
Release decides how quickly the bass climbs back to full level, and it matters more than the other three combined. Too short and you get a click or a lumpy, stuttering low end. Too long and the bass never fully returns before the next kick lands, so your whole low end sits several dB down for the entire song and the mix goes thin without you noticing. The whole art of sidechaining is getting the bass back to unity just before the next hit.
Two more controls appear on modern plugins and both are worth knowing. Hold keeps the gain reduction pinned at full depth for a set time before the release begins, which gives you a squarer, more deliberate duck than a compressor's natural curve. Range (sometimes labeled depth or max GR) caps how far the reduction can ever go. Set it to 5 dB and no matter how hard you drive the threshold, the bass will never drop more than 5 dB. Range is the single easiest way to keep an aggressive setting from swallowing your low end.
| Goal | Ratio | Attack | Release | Gain Reduction |
|---|---|---|---|---|
| Transparent low-end cleanup | 3:1 – 4:1 | 10–20 ms | 80–150 ms | 2–4 dB |
| Modern pop / hip-hop pocket | 4:1 – 6:1 | 1–5 ms | 100–200 ms | 4–6 dB |
| House / techno pump | 8:1 – 10:1 | 0–1 ms | 60–70% of a beat | 6–12 dB |
| Ducking a reverb return | 4:1 | 1–5 ms | 150–300 ms | 3–6 dB |
Set the release with your eyes before you trust your ears. Solo the kick and bass, loop four bars, and watch the gain reduction meter. If the needle never returns to zero between hits, your release is too long and your bass is permanently quieter than you think it is.
Setting Release Time by Tempo
Release is not a taste setting: it is arithmetic with a taste adjustment on top. One beat at any tempo lasts 60,000 divided by your BPM, in milliseconds. At 120 BPM a beat is 500 ms. At 128 BPM it is 469 ms. At 174 BPM, drum-and-bass territory, it is 345 ms.
If your kick lands on every quarter note, the bass has that entire window to recover. A release around 60% of one beat is a reliable starting point: long enough that the recovery feels smooth rather than clicky, short enough that the bass is back at full level with a comfortable margin before the next hit. Shorten it for a snappier, more separated sound; lengthen it toward 80% for a deeper, more obvious pump.
RELEASE TIME BY TEMPO
One beat Suggested release
- 90 BPM 667 ms beat 400 ms release
- 110 BPM 545 ms beat 325 ms release
- 128 BPM 469 ms beat 280 ms release
- 140 BPM 429 ms beat 255 ms release
- 174 BPM 345 ms beat 205 ms release
You do not have to do this arithmetic by hand. Our BPM Calculator now includes a Sidechain & Modulation panel that takes your tempo and prints the beat length, the suggested release window, and the tempo-synced LFO rate in hertz for every subdivision, so you can type your release straight into the plugin instead of dragging the knob until it sounds vaguely right.
Two adjustments to that starting point. If your kick pattern is busier than four-on-the-floor (say a trap beat with a kick on the one and a syncopated hit just after the two), set the release from the shortest gap in the pattern, not the average one. And if you are ducking something with a long natural tail like a reverb return or a pad, you can safely go longer, because there is no rhythmic edge for a slow recovery to blur.
Six Uses Beyond Kick and Bass
Kick and bass is the introduction to sidechaining, not the whole of it. Once you understand that any track can trigger reduction on any other track, the technique starts solving problems all over the mix.
Put a compressor on your reverb return and key it from the dry vocal. The tail gets pushed down while the singer is delivering a line and swells back up in the gaps between phrases. You get the size of a big reverb with none of the intelligibility loss. This one trick lets you use far more reverb than you otherwise could. See how to use reverb and how to use delay for the return setups it pairs with.
Sustained pads sit in the same midrange as a voice and mask consonants without ever sounding loud. Key a gentle compressor on the pad bus from the lead vocal and the arrangement opens a hole for every line automatically, bar after bar, with no automation passes.
Stacked harmonies compete directly with the lead because they are the same voice singing the same words. A light duck keyed from the lead keeps the stack huge in the gaps and politely out of the way underneath the main line.
A chopped soul loop already contains its own drums, which smear against yours. Key a compressor on the loop from your kick and snare bus, and your drums cut through the sample instead of doubling it. If you build tracks this way, our guide to making a beat from scratch covers where this fits in the process.
This is the original broadcast use of the technique, and it is still the fastest way to do it. Key a compressor on the music bed from the voice channel with a slow release, and the music drops the moment someone speaks and rises back in the pauses, with no clip-by-clip volume automation required.
Route everything except the kick to a bus, then duck that bus from the kick. The entire track breathes on the beat. The trick most people miss: use a silent "ghost kick" MIDI track as the trigger instead of the audible kick, so you can shape the trigger's timing and length independently of how the drum actually sounds.
Compressor vs. LFO Tool vs. Volume Automation
A sidechain compressor is not the only way to duck a signal, and for some jobs it is not the best one. There are three tools that produce a similar result through different means.
The sidechain compressor is program-dependent: the shape of the duck follows the energy of the trigger. Louder kick, deeper duck. That responsiveness is exactly what you want on a live-feeling record, and exactly what makes it unpredictable when you want a metronomic effect.
An LFO or volume-shaper plugin (the category popularised by tools like LFOTool, Kickstart, and Ableton's own Auto Pan device) ignores audio entirely and draws a tempo-synced volume curve you control point by point. Nothing needs to be routed and no trigger has to be audible, so you can pump a track that has no kick in it at all. For four-on-the-floor dance music this is usually the better tool, because the curve is identical in every bar and you can shape the recovery exactly.
Volume automation drawn by hand gives you total control and takes the longest. It is the right answer for one-off moments (a single bar where the bass needs to disappear under a drop) and the wrong answer for anything that repeats a hundred times.
| Method | Strength | Weakness | Reach for it when |
|---|---|---|---|
| Sidechain compressor | Reacts to the actual performance | Duck depth varies with trigger level | Live drums, dynamic material, transparent cleanup |
| LFO / volume shaper | Identical, tempo-locked curve every bar | Ignores what the music is doing | House, techno, any rhythmic pump effect |
| Volume automation | Total control over every move | Slow; does not scale | One-off moments, drops, transitions |
Common Sidechain Mistakes to Avoid
Ducking far too much. Eight to twelve decibels sounds thrilling on the first listen and hollow on the tenth. Unless you are specifically after the pump as an effect, 3–6 dB is plenty. Set what sounds right, then back it off by a third, the same rule that applies to reverb.
A release that never recovers. This is the quiet mix-killer. If the gain reduction meter never touches zero between kicks, your bass is sitting several dB below where you set the fader for the entire song, and every balance decision you make afterwards is built on a wrong level.
Triggering from the full drum bus. Hats and snares will fire the compressor and your bass will duck on every subdivision, which reads as a nervous, unstable low end. Trigger from an isolated kick, or low-pass the sidechain input around 150 Hz so the compressor simply cannot hear the top of the kit.
Sidechaining everything. Ducking is a fix for a specific collision, not a mixing style. If six tracks are all pumping off the kick, the whole record starts breathing in a way that flattens the arrangement and exhausts the listener across a full song.
Not checking the result in mono. Low frequencies are where mono compatibility problems bite hardest, and a duck that sounds beautifully carved in stereo can reveal a phase or level problem when the club PA or a phone speaker sums it. Check every low-end decision in mono before you commit.
Reaching for it instead of fixing the arrangement. If your kick and bass genuinely land on the same sixteenth for four minutes straight, the honest fix is to rewrite one of the parts. Sidechaining rescues a good arrangement; it cannot rescue a bad one.
Sidechaining is one link in the low-end chain. Once the kick and bass are sharing space cleanly, work through the rest of the dynamics with how to use compression, then check what your limiter is doing to the peaks you just freed up in understanding limiters.
The fastest way to internalise all of this is to build a four-bar loop and listen to it change. Program a straight kick pattern in our Drum Machine, drop a bass line under it, then pull up the BPM Calculator and dial the release from your tempo instead of guessing. Ten minutes of that teaches you more about ducking than any preset ever will, and the settings you learn transfer to every session you open afterwards.
Frequently Asked Questions
What is sidechain compression?
Sidechain compression makes one track duck out of the way of another, most commonly the bass ducking under the kick. The compressor sits on the bass but listens to the kick, so every kick hit briefly pulls the bass down and both are audible instead of fighting.
Why do kick and bass fight each other?
Kick and bass fight because they occupy the same octave: a kick's body usually sits between 50 and 100 Hz, an E1 on a five-string bass is about 41 Hz, and a trap or house sub sits between 40 and 80 Hz. Two sounds at the same frequency simply sum, and the result is a low end with no definition.
How much should the bass duck under the kick?
The duck should be felt rather than heard: enough that each kick reads clearly, little enough that the bass does not audibly pump. Judge it on speakers or headphones that actually reproduce 40 to 100 Hz, because laptop and phone speakers do not, and the decision is made entirely in that range.
Can I use sidechain compression without a kick drum?
Sidechain compression works from any trigger, not just a kick: a snare, a vocal or a silent trigger track can all drive it. The technique is about making room on a schedule, so anything with a reliable rhythm can be the source.