Essential Guide to Sidechaining – All Your Questions Answered

From cleaning up mixes to pumping grooves, here’s a complete guide to creating space, movement and more using sidechain

 

Header Photo: Grace Anne Bobadilla on Unsplash

Sidechaining is one of the most widely used mixing techniques in modern music production, shaping everything from subtle vocal clarity to the unmistakable “pumping” sound of electronic dance music.

Sidechaining dates all the way back to the 1930s, initially used by film audio engineer Douglas Shearer, who used early compressors as a “de-esser”. Shearer thought of a way to remove sibilance from vocal recordings by triggering his compressor only when specific sibilant sounds appeared.

In the decades that followed, sidechaining became used for voiceover recordings, ensuring that a song dropped in volume when a radio DJ spoke into the microphone. Over time, sidechain compression became heavily popularised in modern music through the rise of French Touch or French House, gaining global recognition through artists like Daft Punk.

Today, sidechaining is both a problem solving mix technique as well as a stylistic choice, used across numerous genres to create space, clarity and movement in a mix.

 

What is Sidechaining? Understanding the Core Concept

In essence, sidechaining is simply using one audio signal to control the processing of another audio signal. It’s most commonly used for sidechain compression - where an audio signal like a kick would be used as a trigger for compression on a bass or lead element. Using an external signal to modify the processing of another signal is a really effective way to process audio, where changes are made based on the pre-existing structure of your song.

These days, sidechaining is not just limited to compression; it can apply to gates, equalisers, reverbs and more! The most basic way to think about sidechaining is “one sound tells another to get out of the way”.

 

 

Why do producers use sidechain compression?

One of the hardest parts of producing music is getting a clean mix, and one of the main hurdles between writing a track and mixing down is often getting each element of your track to sit in its own space. Meticulous arrangement will only get you so far in this regard and eventually all producers succumb to using some creative tricks to achieve a well rounded mixdown.

 

Avoid frequency clashes

Using sidechain compression helps to add clarity to your mix by avoiding frequency clashes. When two elements with similar frequency content overlap, it can create spikes in volume which are often problematic. Take the example of a kick drum and a bass, both exist in the low end of the frequency spectrum and both are key elements of a good dance track. In order to make the two work together in your mix, you can use the signal of the kick drum to trigger compression on your bass, creating momentary space for your kick to shine before the bass returns to full force whenever the kick is not playing.

 

Add groove and the “pumping” effect

Using sidechain can help to add groove to your track by ducking elements out of the way simultaneously. When used aggressively, sidechaining can duck all your elements together in time, creating extra emphasis on your trigger signal such as a kick or snare. Using sidechaining for reactive processing can really bring your track to life! Check out Daft Punk’s use of sidechain compression in “One More Time” where they use the kick to duck all the other elements of their track.

 

Improve mix balance without EQ

Sidechaining can improve your overall mix balance by reactively changing your track’s levels to allow extra space for your trigger element. A few popular techniques to achieve this include Dynamic Sidechain EQ (Available in FabFilter Pro-Q), Sidechain Compression (Available in SSL 4000 G Bus Compressor) or Sidechain Volume Shaping (Available in Duck 2).

 

How to Sidechain: A Step-by-Step Guide

For simplicity, we’ll stick to sidechain compression here, but the process is very similar across most applications of sidechaining.

First, insert a compressor on your target track (e.g. bass). Next, enable sidechain in your compressor and route your chosen trigger (e.g. kick) to the sidechain input.

 

 

Now it’s time to set the parameters of your compressor. The Threshold controls how loud the trigger signal needs to be to trigger compression, the Ratio controls the strength of the compression applied, the Attack controls how quickly compression starts being applied and the Release controls how quickly the compression turns off (this is very important for a “pumping” groove).

 

 

Typically the threshold should be low enough to always be triggered by your chosen sidechain input when it’s playing, you can set the ratio dependent on how audible you want the compression to be, attack times are generally kept short and release time will control how long the compression takes place - use a medium/long release time for a nice “pumping” effect or keep it short if you just want to clean up your mix.

For a quick video walkthrough, check out Disclosure’s short on how to sidechain like a pro!

 

 

Sidechain Compression Vs. Volume Shaping

Over recent years, sidechain volume shaping has become a popular alternative to sidechain compression - made possible through tools like Devious Machines Duck 2 and Shaperbox 3.

Working to achieve the same objective, volume shaping has one distinct advantage over compression; it ducks your chosen track in time with your trigger without actually compressing the signal. This is useful because depending on your chosen sidechain input, compression can be inconsistent, hard to tweak and sometimes unpredictable.

Variations in the level of your sidechain trigger can cause inconsistent compression and attack and release times are often provided in milliseconds rather than beat divisions which can make getting the right groove prove difficult. Volume shaping removes that uncertainty; it provides complete ducking all the way to silence, allows you to draw a specific curve for your ducking, often works in musical beat divisions and provides consistent results every time.

 

 

Ultimately, sidechain compression is always a trustworthy choice for effectively mixing a track and sidechain volume shaping is often better for emphasising the rhythmic “pump”, working more like a sound design technique.

 

Do You Always Need to Sidechain?

The short answer is no, not every mix needs sidechaining and overuse or use in an improper context can easily make mixes sound unnatural. Sidechaining can become a staple technique, but it’s important to remember that it’s often masking an overlap in clashing frequencies and the only true way to fix clashing frequencies is through EQ and careful arrangement.

Sidechaining is a tool but not a rule and it’s always worth exploring multiple solutions to one problem. No amount of sidechaining can fix a badly mixed track so sometimes it’s good to go back and check on the basics first. With that being said, sidechaining is often used more subtly on genres such as Metal, Jazz or Soul that may be looking for a little more space in their mix rather than an “in-your-face” stylized effect.

 

Advanced Sidechaining Techniques

For anyone who’s already mastered the basics, sidechain goes much further than just compression! Next, we’ll discuss some lesser known uses of sidechaining and how they can benefit your tracks.

 

Target Bands with Frequency Specific Sidechaining

Instead of ducking the entire signal of a track, you may want to only reduce specific frequency ranges. This is a more detailed way to clean up frequency clashes (e.g. vocal and lead) without affecting the frequency content that is not clashing.

One of the best ways to achieve this is using Dynamic EQs like FabFilter Pro-Q or Scaler EQ as well as multiband compressors like FabFilter Pro-MB. Using frequency specific sidechaining offers greater technical precision and can create more transparent mixes compared to using full-band sidechain compression or volume shaping.

 

 

Sidechaining Reverb and Delay

Sidechaining can be really effective when applied only to wet signals on effects like reverb or delay. This is commonly used as a vocal mixing technique, where a wet reverb signal is ducked when the vocal is present and then the reverb swells in during the gaps between vocal lines.

Sidechaining wet signals can improve mix clarity whilst maintaining the spacious nature of a reverb or delay during silences in the dry signal. This technique is particularly useful for vocals, leads or dialogue.

 

 

Ghost Sidechaining Explained

Sometimes using audio as a sidechain trigger can introduce latency between audio playing and a sidechain triggering, often caused by intensive processing or plugin latency. One of the best fixes for this issue is using a “Ghost Sidechain”, often a muted audio signal or a MIDI signal instead of an audible source.

This gives you full control over timing without relying on an instrument that’s actually playing in your song. It can be really useful when you have latency issues, a complex or inconsistent trigger pattern or you want to create a pumping effect that follows a different groove.

 

 

Make Reactive Grooves with Sidechain Gating

Instead of turning down a track when triggered by a sidechain input through a compressor or volume shaper, you can use a sidechain gate to open and close a sound rhythmically whenever triggered by a sidechain source. This creates choppy, rhythmic effects rather than smooth pumping - enabling a really useful sound design technique for creating complex rhythmic elements that fit stylistically within your track.

A great way to try out this technique is to take a long, static piece of audio like foley or noise, apply a gate and set your sidechain input to your drum mix, percussion or tops channel. After tweaking threshold, attack, release and floor settings this can create a very convincing layer that sits on top of your drums or percussion in order to beef up your mix or add texture to pre-existing sounds. You can even take this one step further and use a ghost trigger for your sidechain input to create brand new rhythmic sounds that can be easily tweaked using your ghost trigger channel.

 

 

The best plugins for sidechaining

Almost all DAWs have some great options built in, typically most stock compressors will contain a sidechain option with sidechain gates available here and there. Effects like dynamic sidechain EQ are typically more of a premium feature available on third party VSTs.

 

FabFilter Pro-Q

FabFilter Pro-Q has a sidechain option available for dynamic EQ. Route your trigger signal into Pro-Q’s sidechain input, create an EQ band on the target track, enable dynamic mode and then set the band to respond to the external sidechain so the specified frequency range boosts/cuts when triggered.

 

Zynaptiq Morph

Zynaptic Morph uses a sidechain input signal to blend two sounds together. Place the plugin on one of the tracks you want to blend, and select the other track as your sidechain input. Morph will analyze the structural properties of both sounds and use mathematical algorithms to fuse the two sounds together, with an XY pad for extra control!

 

FabFilter Pro-MB

FabFilter Pro-MB uses a sidechain input for dynamic multiband compression. Send a trigger signal to the plugin’s sidechain input, create a band on the frequency band you’d like to control, switch the band to external sidechain mode and it will compress your target track only when the trigger signal reaches over the threshold.

 

Kilohertz Multipass

Kilohertz Multipass allows the use of a sidechain input to modulate any effect that is applied to a frequency band. This gives you the ability to use a trigger sound to control parameters such as distortion, filter cutoff, or effect dry/wet.

 

Devious Machines Duck 2

Devious Machines Duck 2 has a sidechain input feature for volume shaping using an audio or MIDI trigger. Route a sidechain input into Duck 2, select Sidechain under the trigger options, set the threshold and then draw a custom curve that is triggered each time the input signal is received.

 

Cableguys Shaperbox 3

Cableguys ShaperBox 3 includes a volume shaper which can be triggered using an audio or MIDI sidechain input. Use ShaperBox’s volume shaper to draw a curve and route your sidechain signal to trigger the envelope so any modulation follows your sidechain input.

 

Arturia Comp VCA-65

Arturia Comp VCA-65 is a hybrid style compressor that allows you to use a sidechain input for compression. Send a trigger signal into the sidechain input, adjust the threshold, ratio, attack and release so the incoming signal controls how much your chosen track is compressed.

 

Scaler Music Scaler EQ

Scaler EQ has a sidechain input for Dynamic EQ allowing you to suppress out of key harmonics or boost in key harmonics using a sidechain trigger. Route a trigger signal into the plugin and turn dynamic mode on for any band that you want to control using your trigger signal.

 

Conclusion

Whether you stick to sidechain compression or explore advanced techniques, mastering sidechain will give you greater control over your sound. From careful mixing to adventurous sound design, sidechain offers creative possibilities that go far beyond traditional techniques and getting a hold on the numerous ways to use it will add a powerful asset to your production arsenal. As with any technique, use it with intention and always let your ears guide your final decision making.