Basic Production – Sidechain Compression

Well now, look at you. You have some awesome plugins to play with, you have tons of awesome song ideas in your head, and you’ve even started to work on some of them, thanks to a certain tutorial series which taught you how to get started with music production. Only problem is, there are certain effects you can hear in songs you’re using as your inspiration which you can’t figure out! That’s where we come in.

The technique known as “sidechain compression” or, in some production circles, “ducking” is used in nearly every electronic dance song imaginable. Allow me to provide you with one example in which it’s quite obvious.

This song, “Gunsmoke” by Bjorn Akesson, is one of our favorite electro-trance songs of all time. The video starts at the buildup to the drop, and when the drop comes, the pulsing should be readily apparent in the bassline. Every time the kick comes in, the bass becomes quieter before pulsing back to its full volume. Now, the seemingly remarkable part of this is that even in parts where the kick drops out, the bass continues pumping. However, this is a fairly easy technique to do, and we’ll be showing you on a later date.

First, we have to take care of some basics.. You will need a basic compressor for this; however, Reaper comes with a rather capable basic compressor called ReaComp. You will also need some kick samples, and if you don’t have any, you can grab some here. It also helps to have a sampler plugin – again, Reaper comes with one titled ReaSamplOmatic5000. However, a sampler plugin is not completely necessary, as most DAWs allow you to place raw audio files directly into the layout area. You should also have a synthesizer of some sort.

Blank ReaperNow that we have all that taken care of, go ahead and start Reaper, and create a new project if a previously-loaded one comes up. You’ll be back to the familiar clean slate of Reaper, as shown in the image on the right. As we described in our previous series, you have the sidebar on the left which is where all the channels go, and on the right is where you will lay out your song.

Insert PluginsOnce it’s open, go ahead and insert a virtual instrument on a new track twice: one with ReaSamplOmatic5000 (or whatever sampler you’re using) and one with a synthesizer of some sort – we’ll be using the fantastic, free u-he TyrellN6. If you do not know how to do that, simply right-click on the sidebar, then select “Insert virtual instrument on new track…” and choose the respective plugins. Your program should now look something like the image on the left.

SamplerWe’re going to ignore the synth for the moment – we only really need it to produce sound – and we’re going to load up the sampler with our kick sample instead. To do that, first click the “Browse…” button on the top-right of the input area of the plugin (below the big, ominous black box), and use the dialogue which opens up to select the sample. I’ve used a kick from the “Vengeance Trance Sensation Volume 1” pack. Once your sample is loaded, click the dropdown list next to “Mode:” in the top-right of the input area and select “Sample (Ignores MIDI note)” to finish it off, which should make your window look somewhat like mine. You can go ahead and close the sampler plugin window now.

Since we have that all finished up, we can move onto the next part – sidechaining the kick and inserting the compressor. Sidechaining the kick is rather easy. On its channel (labelled “ReaS..5000” on my screen) click the “I/O” button next to the channel name. A small window will appear showing different sends and receives of the channel. Under Sends, click the dropdown menu and select the synth channel, in this case “1: TyrellN6.” Now the kick’s audio will be sent to that channel, but that will cause problems in the mixing stage I/Obecause now the audio will be coming out of two channels rather than just one. To remedy this, look underneath the new I/O information in the Sends area to where it says “Audio: 1/2 => 1/2,” then select the second “1/2” and click “New channels on receiving track,” then “3/4.” Now the kick’s audio will be outputting on the synth’s channels 3 and 4, which do not output to the Master track. You will also need to look for where it says “MIDI: All => All” and change the first entry to “None.” Your I/O panel should look like the image on the left.

MIDIBefore we set up the compressor, we should create some MIDI information on our synth so that we can properly tweak the compressor with audio running through it. Close out both of the plugin windows for now, then create a MIDI clip on the synth channel as described in the fourth part of our previous tutorial and fill it up with some notes. You will also need to some MIDI information on the kick track, so create a basic clip there too. Here are what ours look like. Make sure you click the button that looks like a refresh button in the Transport area to enable Repeat; it will highlight green once it’s enabled.

ReaCompNow it’s time for the compressor. Start the ‘song’ playing by either clicking the play button or hitting space on your keyboard so that we can hear what we’re doing. It’s not going to sound spectacular, but it works for now. Once you start hearing audio, click the green “FX” button on the synth track underneath the Mute and Solo buttons and next to the pan dial, and the synth plugin window should appear. Click “Add” at the bottom of its sidebar, then select ReaComp.

ReaComp EditedWith the audio file continuing to play, first set the “Detector input” to “Auxiliary Input L+R.” This will cause ReaComp to look on channels other than 1 and 2 for audio information, such as 3 and 4, where we have the kick inputting. After that, set the Ratio to something relatively normal to start with, such as 2.0:1, and lower the threshold down below the green volume information. For demonstrational purposes, we’re putting ours down to -20dB. Now it’s time to play with the release time. Basically, release controls when the compressor turns itself off. The faster the release, the quicker and more noticeable the pulse will be, generally. We’ll be setting ours to 50ms. We can also play with the attack too, which controls how quickly the compressor turns itself on, and we’ll be setting ours to 15ms. If you want the pulse to be more dramatic, simply increase the ratio and/or decrease the threshold.

That’s all we have on our end. Feel free to continue exploring and playing around with this – that’s the best way to learn after all!