What Is Sidechain Compression? + 6 Sidechain Tips For A Better Mix



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Q: What Is Sidechain Compression?

A: Sidechain compression is an effect that’s used to make a channel’s audio duck out of the way of another, incoming audio signal (sidechain input). For instance, let’s say we were going to use a Kick Drum as the sidechain source. The only time the compressor would apply compression is when the Kick Drum signal hits. This creates an extremely quick volume ducking effect, & can make your music sound like it’s pumping.

sidechain compression fact sheet
icons from: flaticon

Sidechain compression is an extremely popular mixing tool when trying to make space for certain elements in a track.

I always use sidechain compression on my bass and melodic elements, with 2 compressors, and the sidechain sources, as the Kick Drum & Snare Drum.

This allows the melodic elements that are clashing with the Snare (or the low bass frequencies that are clashing with the Kick), to momentarily duck out of the way, & give a pocket of space for the Kick & Snare to breathe.

If you need to brush up on your compressor knowledge a little more to understand this, check out our what is compression in music guide.

How Do You Use Sidechain Compression?

To use sidechain compression, you’ll need a compressor plugin that has a sidechain input option.

Don’t worry about this, most stock compressors have this option built in, & you don’t really need a 3rd party plugin to use sidechain compression.

You can use sidechain compression on a number of things, from melodic elements, to percussive loops, a vocal track and a whole lot more.

How To Apply Sidechain Compression To Anything In 5 Easy Steps:

Step 1: Open up a compressor on the channel you want to add the ‘pumping effect’ to.

sidechain compression tutorial

Step 2: Select the sidechain input signal you want.

This is what will be used to trigger the compression & duck your audio out of the way.

Try using your Kick track here.

how to turn on sidechain input ableton

Step 3: Turn the ratio up really high – somewhere between 16:1 – inf:1.

This will apply a lot of compression when the Kick drum hits, squashing the signal out of the way of it.

If you’d like a more subtle compression, just play around with the ratio settings until you find something that suits the style you’re going for.

For EDM, we want a big pumping effect – so you’ll want the ratio high if that’s what you’re going for. In other genres, you may want it to be more subtle & organic.

Step 4: You’ll notice you can’t hear the compression working yet. That’s because you need to pull the threshold down for the compressor to start reacting.

So go ahead and pull the threshold down to hear the compression working. The setting depends on your input signal here, so listen & change accordingly to suit the sound you’re going for.

ratio & threshold sidechain compressor

Step 5: Tweak the attack and release settings to your liking.

Attack time is how fast your compressor will react to the Kick track. Release time is how fast or slow the compression will fade out.

You’ll want a fast attack to apply the sidechain compression quickly. You can also alter the release time to remove artificial clicking noises (if you get them).

Step 6: Makeup gain

When you compress something, the gain gets reduced, so we want to add the ‘lost’ gain back into our compressed audio.

You can use the makeup gain knob to do this. Check the gain reduction meter to see by how much you’ve reduced the gain, & turn the makeup gain up by that much.

If the gain reduction meter shows -3db, put the makeup gain to 3db.

How To Get Your Sidechain In Time

You’ll notice that you’ve only got attack and release settings on the compressor, and nothing to sync it to the grid with.

So, to get this in time with everything else in your track you’re going to want to set your attack time to the lowest it can go. You’ll then use your release time to change the timing of the sidechain compression.

In this case we’ll want to use a conversion formula to convert 1/4, 1/8, 1/16 notes etc into a ms (millisecond) format.

We can do this by using this formula:

60,000 ms (1 minute) / Tempo (BPM) = Delay Time in ms for 1/4 note beats

So let’s say we have a track at 120BPM…

60,000/120 = 500

500ms will be the equivalent of a 1/4 note. This is what you’ll set your release time to, to get an in-time, sidechain pump.

You can then just continue halving (or doubling) the ms time, to sync the sidechain to faster or slower note divisions.

For instance: if we have 500ms as a 1/4 note for 120bpm, 250ms would be an 1/8 note & so on.

You can also use this tempo & delay to time calculator.

6 Sidechain Tips For A Better Mix

So know you how to use sidechain compression, you’re almost halfway to being an EDM star or mixing engineer pro.

But where can you use it to clean up mixes & create space for your track elements to breathe?

1. Sidechaining Bass To Create Room for The Kick

This is one of the most common techniques used when using sidechain compression. The kick drum & bass usually occupy the same frequency range (especially in dance music).

Therefore, to allow the kick drum hits to be more audible, & clash less with the bass, you can use sidechain compression to duck the bass out of the way of the kick. This creates more space for the kick drum to truly thump through a mix.

Here’s how you can do it:

Place a compressor on the bass track that you want to sidechain to the kick drum.

Then select the sidechain input as the kick drum. This will give the compressor a signal to ‘duck’ out of the way of.

After this, put your ratio setting anywhere between 8:1 – inf:1 (if your compressor goes up there).

Then, start to bring the threshold down, until you can hear the bass ducking out of the way of the kick drum.

You can play around with the attack and release settings on your compressor to have full control over how your sidechain effect sounds.

Finally, increase the makeup gain to match the amount of gain you have reduced by compressing the signal.

Generally you’ll want a fast attack time & the release can be changed for taste.

Remember that these are guidelines to help you understand & hear how sidechain compression works. Don’t be afraid to break the ‘rules’ & go crazy twisting knobs.

2. Sidechained Reverb for Pumping Atmospheres

Sidechaining reverb can make for some really nice atmospheric results in your tracks. It’s great for adding high end, stereo & atmospheric sounds that pump with your track.

I’ve personally used it a lot to fill out space in a mix & to add an extra layer of goodness.

Here’s how to sidechain a reverb:

Open up a massive reverb. I like to use Valhalla Supermassive (which is free & we included it in our best free VST plugins list).

Place a compressor after the reverb & choose a sidechain source. In this instance I’m going to use the kick drum as a sidechain source, but you could use anything you want.

Now you’re going to want to find that kick track again & set it to ‘sends only’. After doing this, you won’t be able to hear the kick, but you’ll be able to hear it affecting the reverb.

The reverb will be ducking out of the way of the kick every time you have it playing. You can create more interesting rhythmic patterns by changing your kick pattern about.

Make sure to add back any gain that you reduced due to compressing. Check the gain reduction meter and see how much you need to increase the makeup gain to. We are only adding what was lost.

Pro Tip:

You can get similar results by placing an auto pan or tremolo effect after your reverb effect.

Set the phase to 0 degrees and it will act as an LFO/sidechain pumping sound. You can then automate the sync rate to get really interesting & creative results.

Listen to it in context in this beat.

3. Sidechain All Melodic Elements To The Snare

When you’re making tracks that have a lot of elements, you’ll find the snare can get lost amongst all the instruments you have.

By sidechaining the melodic elements out of the way of the snare, you reduce the volume of the track every time the snare hits. This gives it a little pocket of space to breathe, while keeping the volume change unnoticeable to the listener.

To try this technique out, follow these steps:

Group all of your main melodic elements together. If you can’t find this in your DAW, simply send them all to a bus, but make sure to select the audio to ‘sends only’ so it doesn’t double the volume.

On this group, open up a compressor & select your snare as the sidechain input.

Increase the ratio to 8:1 – inf:1, & turn the threshold down until you can start to hear things duck out of the way.

This will sidechain all the elements to the same attack & release times + with the same intensity.

If you’d like to control the intensity (threshold & ratio) of each instrument, open up separate compressors on each of the elements you want to sidechain.

You can then have full control over how much the sidechain compression acts on your instrument.

4. Sidechaining To Create Space for Vocals

Vocals are tricky to mix & can get lost in your tracks among all the other instruments you have playing. It’s great on guitars, bass, keys or anything that will clash frequencies with your vocals.

Unlike the above, you’ll want this to be fairly subtle otherwise it will sound like a radio announcement over your track, & the volume will drop a large amount.

To sidechain for space with vocals, follow these steps:

Find the instrument that is interfering with your vocal track, open up a compressor and choose the vocal track as your sidechain input.

Set your ratio low to begin with 2:1, & adjust the threshold until you see gain reduction of anywhere between 1-3db.

Set your attack and release time to quick settings. You want the instruments to duck quickly, & recover their volume quickly when the vocal stops.

After this, play around with ratio or threshold settings to adjust to your liking. Personally I wouldn’t ever go above 5db gain reduction.

5. Sidechain Select Frequency Bands for Pinpoint Accuracy

Ableton Sidechain Compressor EQ

On the Ableton stock compressor, when you select the sidechain option you can also choose an EQ frequency range to specifically select what part of the kick you want to come through.

For instance, if you select the low boost, it will boost the low end of the kick – making the sidechain’s gain reduction more prominent. This is useful when you’ve got a lot of clashing in your low end & want it to heavily duck out of the way to make space.

You can also choose high pass filters to make the gain reduction less prominent in the low end (for a kick). This can be used more creatively & tends to make a better pumping effect.

By having this ability to choose the filter type, you can change the sound of your sidechain compression drastically, so it’s an option worth playing around with.

This video will help to explain how it affects the audio in more depth.

Multi-Band Sidechain Compression

Let’s say you’ve got a sample that has bass, & melody playing through it, but when you sidechain that sample, you don’t want it to affect the entire sound & want to keep the top end present as it is.

(this can also work with bass patches that have both high & low end register to them)

Here, you can use multi-band sidechain compression.

To do this, you:

  1. Open up an audio effect rack.
  2. Create 3 chains & open up multibands on all of them.
  3. Solo the low on the 1st, the mid on the 2nd, & the high on the 3rd.
  4. Now you have 3 bands to choose from. In this instance, we want to sidechain the low.
  5. Open up the compressor on the low chain in your audio effect rack, & set up a sidechain with your kick.
multiband sidechain compression tutorial

This will only duck the lows out of the way, allowing to create space in your mix for the kick drum, without affecting the top end of your sound.

It’s an extremely useful mixing tool, but if you want that pumping sound you’re better off sidechaining the whole sound.

6. Ghost Sidechain for Interest Rhythmic Results

Ghost sidechain can also be a very interesting creative tool for sound design & creating obscure pumping rhythms.

Here’s how you can do it:

Open up a compressor on the channel you want to sidechain.

Once you have your sidechain input, you’re going to want to set that channel to ‘sends only’. This means the sidechain input won’t be audible in our mix, but will still affect the audio.

You can then set up your sidechain however you like, & can draw in different MIDI rhythms you want the sidechain to react to.

Summary

Sidechain compression is an effect that’s used to make a channel’s audio, duck out of the way of another, incoming audio signal (sidechain input).

It’s extremely useful to create space in your mixes or for creative purposes.

In this article, we’ve explained the basics of sidechain compression, and given you a few examples you can try for yourself, to get more to grips with sidechain in your own music production sessions.

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