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Advanced Sidechain Techniques - How To Supercharge Your Mix's Potential

Jan 07, 2025

Go beyond pumping and ducking, and get new capabilities and control by going deeper with your sidechain routing than ever before.

Advanced Sidechain Techniques - How To Supercharge Your Mix's Potential

Sidechaining is a very common technique in music production, and given how vital it is to achieving modern effects, is arguably worthy of inclusion in any beginner’s mixing and sound design course. That’s right – music production has moved on from the days when activating a sidechain or ‘key input’ was an advanced technique in itself.

But there’s still a way to push sidechaining to its limits. In this article, we’ll show you how to hack your sidechain in order to get more out of your plugins – and of course, we’ll also tell you why you would go to such lengths in order to do that! First, we’ll start with the basics then build up to the advanced work. To skip through this article, click on any of the sections below…

  1. Review: How Sidechaining Works
  2. Every Dynamics Device has a Sidechain
  3. Traditional Sidechain Technique: Pumping
  4. Traditional Sidechain Technique: Ducking
  5. Hacking the Internal Sidechain: Hybrid Routing
  6. Taking Sidechain Filtering Further: The Band-Pass Filtered Gate
  7. Going Further: Sidechain EQ
  8. Snappy Compression Using a Delayed Sidechain
  9. Lookahead on Your Own Terms

Review: How Sidechaining Works

It’s worth going over this subject to get every reader up to speed, but if you’re already fully aware of the signal paths under the hood of a dynamics device, you can skip on a little lower.

Every Dynamics Device has a Sidechain

The first interesting point to note about sidechains is that every dynamics device has a sidechain – even those that were designed before inputting your own external audio signal was possible. In a dynamics signal path, the input signal must have a ‘detection circuit’ that splits off the signal in order to analyze its properties. This is the fabled ‘sidechain’, or in this case the ‘internal sidechain’, with the original signal route going off for level processing before being output.

Diagram of internal sidechain signal routing

What we tend to call a sidechain – although once it was known as a ‘Key Input’ – is actually when using an external sidechain: inserting your own signal from outside to trigger the detector, while the original signal is processed.

Diagram of external sidechain signal routing

Traditional Sidechain Technique: Pumping

This sidechain technique involves adding a compressor over a long, sustained sound such as a pad, and then feeding that compressor with a sidechain input from a kick drum or other steady, rhythmic sound. With a deep gain reduction and a nice long attack (as we’ve done below using our dbx160 plugin), you’ll get a pumping effect.

A synth in a DAW being rhythmically pumped by the kick signal, by way of a sidechained compressor

The sound of this effect is obvious in the audio example below, which leaves the kick audible, so you can hear the trigger and its effect on the volume curve of the pad sound. (By the way, check out our OneKnob Pumper for a far simpler way to set this up).

The effect is often used to pump way more elements of a song or even entire master busses. You can hear it audibly in a lot of EDM and mainstage music, very notably in the drop of David Guetta’s Titanium, to give a recent prominent example.

Traditional Sidechain Technique: Ducking

Another way of using a sidechain is far quicker than the audible pump – in fact, it’s not meant to be audible at all. By quickly ducking one ‘slow’ element (often a bass) while another ‘fast’ element plays (usually a kick), we make room for the fast element by cutting a hole in the background element. Usually, what has happened is imperceptible, but the effect is an increased clarity in the kick and the ability to turn it up louder.

Moving the bass audio out of the way as the kick hits in Scheps Omni Channel 2

This is one tactic towards Mixing Kick and Bass to Perfection – you can find more in our article.

Hacking the Internal Sidechain: Hybrid Routing

For the setups we’re going to make in this article, we’re going to break the usual split between external and internal sidechain signals, using a bit of both to do our thing. We’ll duplicate our original signal and use it as an external sidechain input, while making sure it’s not actually routed to our master output. We could call this a ‘Hybrid Sidechain’.

Setting up a duplicate of a channel in a DAW for use as an amended internal/external hybrid sidechain later

What this means is that we have all the flexibility of a full track in our DAW, but controlling our sidechain signal, changing how our dynamics device interprets the signal and using full plugins and track movement to do it.

The Band-Pass Filtered Gate as a Layering Device

Traditionally, a sidechain filter is employed on a compressor in order to reduce the influence of low-end elements such as kicks, which are often more powerful in level than the rest of the audio spectrum. By dulling down the kick’s influence on compression, gain reduction is less dramatic and pumpy, making things more transparent.

With our newly set up hybrid sidechain, we can go further than just high-passing, also adding a low-pass to create a narrow band-pass filter that will only trigger compression when a certain range of frequencies reaches the threshold.

A band-pass filter placed over a duplicated channel ready to feed a sidechain input

With our drum loop doubled, the duplicated copy isn’t routed into the output or master bus to be actually audible, but is sent to a gate we’ve placed over a noise signal, a constant noise signal that’s running on a separate track.

By band-passing this gate strictly to the snare’s key frequencies, we can have the gate trigger only when the snare plays, letting through a burst of white noise (or any replacement signal) that can be triggered every time the snare plays and blend with its sound as a new layer. The gate settings have to be fine-tuned to change the character of the white noise burst.

We would also want to do some more alteration to this setup to sculpt the layer of white noise to fit it in better with the whole beat, but you can see the technical aspect happening here.

A sidechained white noise track in a DAW, as used to layer white noise bursts when the sidechain triggers the gate

Sidechain EQ

Another development from sidechain filtering, sidechain EQ lets you de-emphasize or emphasize any frequencies you wish in order to weight the response of your compressor’s action with frequency.

Sidechain EQ setup

Kicks are often high in level due to their low-frequency nature, but snares can also creep up. Using sidechain EQ on a hybrid sidechain setup (as above using SSL G Channel), we can give our compressor a version of the signal where the snare is higher, making the compressor react more to it, and less to the other elements happening around it.

The advantage of sidechain EQ is that you can pull certain frequencies and therefore certain elements out of the processing or push them harder into it.

Snappy Compression Using a Delayed Sidechain

Usually, a compressor gives us some extra parameters to alter its timing. These usually include Attack and Release, and you may get some extra power, such as Hold, to keep your gain reduction constant for longer, but how about having your own extra control over timing with the help of a duplicated, ‘hybrid sidechain’ setup, sounds interesting right?

One classic compression technique is the act of increasing your Attack time until a transient has enough time to ‘pop through’ it, with most of the compression coming after that transient. But this still leaves you with a slow attack time. We can get even snappier.

After duplicating your signal to create its own external sidechain (and making sure the duplicate isn’t audible in the mix), move the duplicate track slightly later in time. You can do this either literally by shifting the audio region in your DAW or by adding a delay plugin set 100% wet. As with the compressor’s Attack, do this to the point where the snare’s transient is just ‘popping through’.

Snappy Compression Using a Delayed Sidechain

Now with the sidechain signal acting later than it was before, we can operate with a short attack time, getting more control over the body of the sound after the transient is left even more spiky. We can even tackle compressing the transients separately using serial compression techniques.

Results may be a little exaggerated for demonstration purposes.

Lookahead on Your Own Terms

In a new slant to the idea of the previous technique, how about moving your duplicated audio track (aka ‘hybrid sidechain’) earlier in time rather than later. This acts as a ‘Lookahead’ control for your attached dynamics device, making it react earlier than it usually would.

This could be a solution for a dynamics device that doesn’t give you lookahead options or enough lookahead options, or it could simply be used as a creative technique. If your audio is moved a logical (such as a 1/16 or 1/32 forward), then the resulting effect could be a more musical ‘pump’ of a different sort to the traditional sidechain effect.

Getting Better Track Separation: The Smart Way

Now that you are armed with these advanced sidechain mixing techniques, start to think which plugins in your library could work with more flexibility. Maybe your favorite compressor is missing a built-in sidechain filter control, or maybe you would like to give your go-to buss compressor a slightly different attitude… all possible with what you’ve learnt in this article today. BUT, if you’re looking for a super simple sidechain starter kit, check out Curves Equator. The sidechain features within this is by far one of the simplest ways to get better track separation in any mix!

In the video below, discover how to use Equator’s powerful yet oh so simple sidechain and Learn features to seamlessly balance competing elements in a mix. By using these tools, you can ensure that your tracks sit more harmoniously together, allowing each element to shine without clashing. Equator makes it easy to achieve greater clarity and cohesion in your mixes, all with minimal effort—saving you time while delivering professional-quality results.

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