Sidechain Compression Guide

Learn › Mixing, EQ & Compression › Sidechain Compression

Knowing how to sidechain compress music production tracks is one of the defining mixing techniques in electronic music. Used well, it solves the kick-bass collision problem that plagues DnB and dubstep mixes - creating clean, punchy low end where the kick and bass coexist without fighting. Used badly, it creates either obvious unwanted pumping or no audible effect at all.

This guide covers sidechain compression in working depth. The classic kick-to-bass setup, the parameters that determine pump versus transparency, frequency-filtered sidechain for more surgical results, LFO-based alternatives, and the DAW-specific routing for Ableton, FL Studio and Logic.

What Sidechaining Actually Is

A normal compressor responds to the audio level of its own channel - the audio you hear is also the audio the compressor analyses for triggering. Sidechain compression separates these: the audio you hear is from one channel, but the audio that triggers the compressor comes from a different channel.

The "sidechain input" of a compressor is a separate audio input that controls the compressor's behaviour. Route a kick drum signal into the sidechain input of a compressor on your bass channel, and the bass channel gets compressed whenever the kick hits - even though the bass is the audio actually being compressed.

This decoupling of "what triggers" from "what gets compressed" is what makes sidechain compression so powerful for mixing electronic music.

How to Sidechain Compress Music Production Bass to Kick

The most common sidechain setup in DnB and dubstep mixing: kick drum triggers compression on the bass. Every time the kick hits, the bass briefly ducks. The kick punches through cleanly; the bass returns to full level when the kick releases.

The reason this matters: the kick and bass both live in the 30-150 Hz range. Without sidechain, the bass tends to mask the kick's transient impact. With sidechain, the bass gets out of the way for each kick hit, allowing the kick to dominate the low end at the exact moments when it needs to.

Attack and Release for Pump vs Transparency

The parameters that distinguish DnB and dubstep sidechain from the more obvious "pumping" sidechain used in house music.

Tight, Transparent Sidechain

The DnB and dubstep approach. The bass ducks briefly and returns quickly to full level. The effect is mostly inaudible as "ducking" - it just feels like the kick has more clarity and punch.

Settings: fast attack (1-5ms), fast release (50-100ms), 3-6 dB gain reduction. The bass returns to full level well before the next kick, leaving the bass mostly intact between kicks.

Loose, Pumping Sidechain

The house and progressive electronic approach. The bass ducks audibly at each kick and the recovery is slow enough that you hear the bass "breathing" back into the mix between kicks.

Settings: slow attack (10-30ms), slow release (200-400ms), 6-10 dB gain reduction. The longer release creates the characteristic "pumping" effect heard in tracks by Daft Punk, deadmau5 and many EDM producers.

The Choice

For DnB and dubstep, tight transparent sidechain is the default. The audience should not consciously notice the sidechain - they should just perceive a cleaner kick-bass relationship. Loose pumping sidechain is a stylistic choice used occasionally for breakdowns or specific creative moments.

The same compressor can deliver transparent DnB ducking or full house-style pumping - the difference is entirely in the attack and release values you dial in.

Sidechain Frequency Filtering

Modern compressors offer a sidechain filter that restricts which frequencies of the trigger signal cause compression. This adds significant precision to sidechain setups.

The use case: a kick drum has both low-frequency content (the fundamental punch) and higher-frequency content (the click and harmonics). Without filtering, the compressor responds to both - it compresses whenever the click triggers as well as when the punch triggers. With a sidechain filter set to only let through the low frequencies, the compressor only responds to the fundamental kick punch.

The typical setup: low-pass the sidechain at 200 Hz. The compressor only responds to the kick's low-frequency content. This creates more musical sidechain because the compressor is responding to the actual punch of the kick rather than its overtones.

Plugins with built-in sidechain filters: FabFilter Pro-C 2, Ableton's Compressor, FL's Fruity Limiter, Logic's Compressor. Most professional compressors include this feature.

Ghost Kick Sidechain Trigger

A more advanced technique: using a separate MIDI-triggered audio source as the sidechain trigger rather than the actual kick channel. This is called a ghost kick or sidechain trigger.

The setup: create a separate audio channel with a simple sine wave or click sample. Trigger this channel with MIDI notes that match your kick pattern. Route this trigger channel to the sidechain input of the bass compressor. Mute the trigger channel so it does not play in the actual mix - it exists purely as a sidechain trigger.

Why use a ghost kick: it gives you complete control over the sidechain timing independently of the actual kick audio. You can trigger sidechain on beats where there is no kick (for rhythmic pumping in breakdowns), trigger sidechain just before the kick hits (for anticipation pumping), or use a different trigger pattern than the actual kick (for polyrhythmic sidechain effects).

Common use: in DnB tracks where the kick has occasional rest moments (a ghost kick can maintain sidechain pumping during those moments) or where the sidechain timing should be tighter than the kick's natural transient response.

Sidechain Reverb for Rhythmic Tails

Sidechain compression is not limited to bass channels. Sidechain on reverb return channels is a powerful technique for managing reverb tails.

The setup: insert a compressor on your reverb return bus. Route the kick (or vocals, or any rhythmic element) to its sidechain input. Set sidechain compression so the reverb return briefly ducks on each trigger.

The effect: reverb tails are present in the spaces between hits but get out of the way of each hit. This is particularly useful for snare reverbs where the tail of the previous snare's reverb interferes with the next snare's transient.

Common settings: similar to bass sidechain - fast attack, fast release, 3-6 dB reduction. The reverb pulses with the kick or snare pattern, adding rhythmic interest while solving the buildup problem.

LFO-Based Ducking - The Alternative

Sidechain compression requires routing audio between channels. LFO-based ducking plugins achieve a similar effect without needing a sidechain trigger - they apply pre-set volume modulation patterns to the channel directly.

The dominant tools in this category: Cableguys Kickstart (the original and most widely used, around £15) and Cableguys Shaperbox (more advanced, around £90). Both let you draw or select a volume modulation curve that the plugin applies in tempo-synced cycles. The effect mimics sidechain compression without needing actual sidechain routing.

Advantages: faster to set up than full sidechain routing, completely consistent (the duck pattern is the same on every cycle regardless of the kick's actual transient response), works without needing a kick channel at all.

Disadvantages: less natural than true sidechain because the duck pattern does not respond to the actual transient details of the kick. The duck is purely time-based rather than audio-triggered.

For most modern producers, LFO ducking has largely replaced traditional sidechain for "sidechain effect" purposes. True sidechain compression is reserved for situations where the duck needs to respond to the actual audio characteristics of the trigger.

Volume Automation as Manual Sidechain

The most precise (and most tedious) version of sidechain: manually drawing volume automation that ducks the bass on each kick hit.

The workflow: identify every kick position in your timeline. On the bass channel, draw a volume automation curve that drops the bass level briefly at each kick position, then returns to full. Adjust the depth and timing of each duck for each section of the track.

This approach gives you complete control over the sidechain feel on a per-hit basis. Different kicks can have different duck amounts. The duck can have any envelope shape you want. The result is bespoke sidechain that matches the music's specific dynamics.

The downside: time-consuming. Even with copy-paste, manual sidechain automation is much slower than compressor or LFO-based approaches. Reserved for tracks where the standard automated approaches do not give the right musical result.

DAW-Specific Sidechain Setup

Ableton Live

Insert a Compressor on the bass channel. In the Compressor's interface, click the Sidechain button to expand the sidechain options. Set "Audio From" to the kick drum channel. Turn on the sidechain (the small power button next to the source selection). Set "Filter" if you want frequency-filtered sidechain - low-pass at 200 Hz is the standard starting point.

The Compressor now responds to the kick channel's audio level. Adjust threshold, attack, release, and ratio for the desired ducking behaviour.

FL Studio

FL's sidechain routing is more involved. In the Mixer, right-click the source (kick channel), choose "Sidechain to this track" and select the destination (bass channel). The kick is now available as a sidechain source on the bass track.

On the bass channel, insert Fruity Limiter in compressor mode. In the limiter's interface, set the sidechain source to the kick channel (1, 2, 3, etc. depending on how many sidechain sources you have configured). Adjust threshold, attack, release, and ratio.

Logic Pro

Insert a Compressor on the bass channel. In the Compressor's interface, click the "Side Chain" menu in the top right. Select your kick drum channel as the sidechain source. The compressor now responds to the kick.

Logic's Compressor supports sidechain filtering through the "Side Chain" expanded section - useful for low-pass filtering the trigger signal.

Common Sidechain Mistakes

Key Takeaways

1. Sidechain compression routes the trigger from one channel and the audio being compressed from another.
2. Kick-to-bass sidechain is the standard - the bass ducks briefly on each kick for clean low-end separation.
3. Tight settings (fast attack, fast release, 3-6 dB reduction) create transparent sidechain - the DnB and dubstep default.
4. Loose settings (slow attack, slow release, 6-10 dB reduction) create pumping sidechain - the house and progressive style.
5. Sidechain filtering (low-pass at 200 Hz) restricts triggering to the kick's fundamental punch, ignoring harmonics.
6. Ghost kick triggers give you complete control over sidechain timing independently of the actual kick audio.
7. Sidechain reverb returns to kick or snare to keep reverb tails from masking transients.
8. LFO-based ducking (Kickstart, Shaperbox) is the modern alternative - faster setup, consistent results, less natural feel.
9. Volume automation as manual sidechain offers complete control but is time-consuming.

Kick One-Shots Built as Ideal Sidechain Triggers

Sidechain compression depends on the trigger signal. Kicks with clean, focused transients trigger sidechain compressors predictably. Kicks with smeared or unfocused transients trigger sidechain in inconsistent ways.

Continue the Mixing Pillar