How to Use Sidechain Compression: 10 Simple Steps

Sidechain compression is a technique where a compressor on one track responds to the signal from a different track, ducking the first track’s volume whenever the second plays. That’s the whole idea. A compressor on your bass ducks the bass every time your kick hits. The result: both sit in the mix cleanly without fighting for the same frequency space. It’s one of the most-used moves in modern production, and once you’ve heard it working right, you’ll wonder how you mixed without it.

Step 1, Understand What's Actually Happening

Standard compression reacts to its own input. The signal gets loud, the compressor clamps down. Simple.

Sidechain compression breaks that rule. The compressor on your bass track is no longer listening to the bass. It’s listening to your kick. Every time the kick hits, the compressor sees that signal and reduces the bass volume automatically.

We ran a bass synth under a kick at 95 BPM with no sidechain. Both peaked at around -6dBFS. The result was a blurry low end where neither instrument had room to breathe. Frustrating to listen to on anything with real subs. Adding the sidechain pulled the bass back 3dB every time the kick hit. The kick suddenly had a body. The bass returned cleanly between hits. That’s the transformation you’re chasing.

Think of it as tempo-sensitive volume automation you don’t have to draw by hand.

Step 2, Set Up Your Routing

The routing is where people get confused. Here’s the exact path.

Place your compressor on the target track. That’s the track you want to duck. In most cases, that’s your bass.

Then tell that compressor to listen to a different source: your kick drum. How you do this depends on the DAW:

In Ableton Live: Enable the sidechain input inside the compressor and set the Audio From dropdown to your kick track.

In Logic Pro: Use the Side Chain menu in the top-right of any compressor to select your kick channel.

In FL Studio: Route your kick to a mixer track, then use the sidechain send option in the mixer to connect it to your bass compressor.

In Pro Tools: Use a bus, send the kick to it, then set that bus as the key input on your bass compressor.

The target is always the track that gets ducked. The source is what triggers it.

Step 3, Choose the Right Compressor

Not every compressor has external sidechain capability. Check before you load it.

FabFilter Pro-C 2 is our pick for this. The sidechain input is clearly labelled, the visual feedback shows you exactly how much gain reduction is happening in real time, and the high-pass filter on the sidechain input (more on that in Step 7) is built right in.

Waves RCompressor works well and is often on sale. The attack and release controls are smooth and the sidechain routing is clean.

Your DAW’s stock compressor is fine for learning. Ableton’s stock compressor and Logic’s built-in Compressor both have full sidechain routing. Start there. You don’t need to spend anything to understand this.

Step 4, Set Your Ratio

For kick-bass ducking, start at 5:1. That’s firm enough to hear the duck clearly without turning your bass into a stutter.

If you want heavy pumping effects, go 8:1 to 10:1. At 10:1 the duck is dramatic and the pumping becomes the effect, not just a tool.

For subtle vocal clarity work (ducking a pad slightly when a lead vocal hits), try 3:1 or 4:1, targeting 2 to 3dB of gain reduction maximum.

Don’t overthink the ratio. Start at 5:1 and let your ears decide from there.

Step 5, Dial in Attack and Release

These two controls make or break sidechain compression. Get them wrong and the result sounds ugly.

For kick-bass ducking: set attack at 1ms to 2ms. Fast. You want the compressor to clamp down the instant the kick hits, so the kick’s transient pokes through the mix clean.

Release is where the magic lives. Set it too short and the bass pumps unnaturally. Set it too long and the bass stays ducked when it shouldn’t be.

At 120 BPM, each beat is 500ms apart. Start your release at 150ms to 200ms. The bass should recover fully before the next kick hits. If you hear the bass snapping back too fast, increase the release. If it never recovers before the next kick, decrease it.

We tested a 4-bar loop at 128 BPM with release times at 50ms, 150ms, 220ms, and 350ms. The 150ms setting was the most transparent. The 350ms turned every bass note into a swell. Both are valid. The 50ms setting sounded like someone was randomly turning a knob. Annoying.

Step 6, Set Your Threshold

Lower the threshold until you see 3dB to 6dB of gain reduction on the kick’s hit. Watch the gain reduction meter, not the waveform.

For subtle ducking: aim for 2 to 4dB of reduction. The listener won’t consciously notice. The mix will feel tighter.

For obvious pumping: 6dB to 10dB or more. This is the classic house and techno pumping sound. It stopped being subtle around 1995 and never came back. That’s fine. Sometimes you want it obvious.

Step 7, Filter the Sidechain Signal

This is the step most tutorials skip. It’s brilliant.

If your kick has a long sub tail (most modern kicks do), the low-end rumble after the transient will keep triggering your sidechain compressor longer than it should. The result is a duck that hangs too long, even with a short release.

Apply a high-pass filter on the sidechain input itself. Not on your kick track. On the signal the compressor is listening to. Set it at around 100Hz. Now the compressor reacts to the punch and snap of the kick, not the sub rumble. Cleaner duck. Faster recovery.

FabFilter Pro-C 2 has this filter built into the sidechain section. In other compressors you may need to insert an EQ on the sidechain bus.

Step 8, Try Frequency-Specific Sidechain

Standard sidechain ducks the whole track. Multiband sidechain targets a frequency range.

This is underrated. On a bass guitar track, the kick and the bass conflict most between 60Hz and 120Hz. You don’t need to duck the entire bass. You only need to duck that range.

Use a multiband compressor with sidechain input, or , and narrow the compression to that band only. The upper harmonics of the bass stay constant. Only the sub range ducks. The mix stays full, but the kick has room.

Step 9, Apply It Beyond Kick and Bass

Sidechain compression works on any two tracks where one masks the other.

Pad ducking under lead vocal: 3:1 ratio, 5ms attack, 300ms release, 2 to 3dB of reduction. The vocal pops forward without you touching the pad fader.

Guitars ducking under snare: Try this on dense rock mixes where the snare disappears in a wall of mid frequencies. Subtle. 2dB reduction max.

The Billie Eilish production trick: duck a whole reverb send with a vocal sidechain. The reverb blooms after the vocal phrase, not during it. The vocal stays dry and close while the reverb tail breathes between words. It sounds satisfying in a way that takes five seconds to set up.

Step 10, Compare Bypassed vs. Active

Toggle the compressor off and on while the mix plays. This is how you know if the settings are right.

Bypassed: the mix should feel slightly cluttered or undefined in the low end, or wherever you’re sidechaining.

Active: it should feel tighter, more energetic, more punchy. Not obviously processed.

If you bypass it and the mix sounds better, your settings are wrong. Adjust threshold and release before assuming sidechain isn’t working for the track.

Pro Tips

Use a ghost kick. In some DAWs, you don’t want the compressor’s trigger track audible in the mix. Create a duplicate kick track routed only to the sidechain bus, not to your master. The original kick plays in the mix. The duplicate triggers compression silently.

LFO shaping vs. true sidechain. Tools like LFOTool (Xfer Records) and Volumeshaper create the pumping effect with an LFO synced to your tempo instead of actual compression. It’s a different animal. True sidechain reacts dynamically to level. LFO tools are rigid but predictable. For EDM four-on-the-floor pumping, LFO tools are often cleaner. For organic genre work like hip-hop or indie, true sidechain wins.

Gain stage before sidechaining. The compressor reads input level to decide how hard to duck. If your kick is low-gain, the sidechain won’t trigger hard enough. Make sure your kick hits -10dBFS or above before it reaches the sidechain input.

Automate the threshold. In a chorus, you want more pumping energy. In a verse, you want transparency. Automating the threshold 2 to 4dB between sections is a clever way to make the effect serve the arrangement.

Common Mistakes to Avoid

Slow attack on the kick-bass duck. Setting attack at 10ms or longer means the kick’s transient hits after the compressor has already started clamping. You lose the snap. Keep it at 2ms or less for any transient-critical ducking.

Ignoring the release time per tempo. A release time that worked at 128 BPM will over-duck at 85 BPM. Every time the tempo changes, revisit your release time. The formula: take one beat’s duration in milliseconds and aim for roughly 70-80% of that as your release target.

Sidechaining the master bus. We’ve seen people new to the technique try sidechaining on the master. Don’t. Route compression to individual tracks or group busses. Sidechain on the master affects every element in your mix simultaneously.

Skipping the frequency-specific option. Ducking the whole bass when only the sub range conflicts is like closing the whole road for a pothole. shows you the better approach. It takes an extra two minutes. The result sounds more natural.