When you think of sidechaining you probably think of sidechain compression right? Although sidechain compression is a vital mixing technique and a fundamental part of electronic music production, it's just one form of sidechaining.
What is sidechaining?
A ‘sidechain’ is simply an ‘input’. You can sidechain a compressor with an audio signal, but there are many other ways of using the technique.
When considering alternative uses for sidechaining, it's useful to remind ourselves what it actually refers to. We can select a source signal to be routed into a parameter within a plugin (say, an effect or instrument), so that the amplitude of the source signal changes the sound of the plugin.
Traditionally a signal, such as a kick, 'ducks' the volume of an instrument every time it hits. However, this sidechaining source signal could be routed to a whole range of instruments and plugins for all kinds of effects. In addition, it's also a great way of building relationships and interplay between different parts in an arrangement.
Sidechaining in Logic
A number of instruments and plugins in Logic offer this sidechaining input functionality. It’s useful to provide an overview of the basics for each plugin in order to give examples of what can be achieved and the creative possibilities.
In this post, we’ll explore sidechaining using two effect plugins and two software instruments to broadly demonstrate the range of options available and get you started.
[Advanced warning: This is a bit of a mammoth post!]
First we need to set up our sidechain signal:
To begin, drag an audio sample into your arrangement. This could be anything you like, but a good place to start is using a drum or percussion loop with some fast attack - this will help to make the effect more obvious.
Set the track output to ‘No Output’. We don’t need to hear the loop itself, it will simply be used as a trigger for the plugins and instruments, and we can still route the signal.
Now that the setup is complete, we can begin triggering Logic’s effects and instruments.
This sidechaining technique is perfect for adding groove and movement to static or sustained sounds, such as pads, basses and leads. I find the best results come from triggering these sounds with drum loops, hats and percussion. It’s also great for syncing parts rhythmically and creating a sense of cohesion.
Let’s add a pad using Logic’s EXS24 sampler - create a new software instrument and choose the EXS24.
Now select a pad sound from the array of options. I’ve chosen to go with the ‘Basic Pad’ preset in this example.
Record in some chords (or drag in some MIDI from a sample pack, whichever you prefer) onto the EXS24 track, so that we have some notes being generated.
Now head back to the track in the mixer and insert Logic’s Noise Gate plugin.
This plugin has a sidechain input on the top right. From the dropdown, select the audio loop we brought in during the initial setup.
When playing the chords back, you should immediately notice a change in the sound as the synth is triggered with the loop via the sidechain input. To increase the amount at which the sound is effected, simply raise the threshold parameter.
The Reduction meter sets the level at which the threshold begins to work.
The ‘Hysteresis’ parameter is useful for controlling ‘chatter’ if the input signal hovers around the threshold amount, thereby smoothing out the overall sound and preventing glitches and stutters. It works by setting the range between the threshold values that open and close the gate.
The ‘Attack’ and ‘Release’ settings are fairly self explanatory. Much like when using a compressor, increasing the attack time will soften the start of the sound, and increasing the release will extend the tail.
Similarly, raising the amount of ‘Hold’ will increase the overall sustain. You can go ahead and adjust these settings to taste.
Logic’s AutoFilter is a bit of an underdog, it’s rarely talked about but it’s actually a very versatile tool, particularly when using a sidechain input. In its basic form it can be used as an alternative to a compressor, ducking the amplitude of a sound whenever the source signal hits. It can, however, create endless variations of effects with a little experimentation.
Remember, a filter controls the frequency content of a sound, mostly by removing specified frequencies. In this scenario, we’ll be configuring the AutoFilter to cut frequencies in response to a sidechain input. Adding filter modulation to a sound can provide a great deal of extra interest for the listener, so it’s a really useful trick within a production.
This time let’s work a little differently. Drag in another audio loop, preferably a chord sequence. For this example, I’ve pulled in the ‘Icy Fauna’ synth loop from Logic’s library as it’s handily recorded at 128bpm. Drag it into the Arrange area and Logic will automatically create an audio track.
Next add an instance of AutoFilter to the track.
We’re not going to be using the distortion or LFO modules for now (as these deserve another article!), so go ahead and disable these. Instead, we’ll focus on creating a 'wah-style' effect using the envelope.
If you play back the loop, you’ll notice that the frequency is being cut by the (you guessed it) ‘Cutoff’ filter - move this around to hear the change. By default, it’s in low-pass mode, so it will be removing high frequency content.
Now add the sidechain input again, using the same drum audio loop. Be careful not to add the synth loop as this would effectively be triggering itself and won’t have much use!
If you bring the Cutoff level back to around 50%, you should begin to hear that the sidechain input is having an effect on playback.
Similar to the Noise Gate plugin, we can alter the amount that the sound is being affected with the ‘Threshold’ control.
To hear this in full form, bring up the Envelope level in the Filter section to ensure that it’s having maximum modulation effect. Now increase the threshold and the filtering should really kick in.
The Dynamic level determines the input signal modulation amount, so feel free to turn this up to 100% for the full effect.
Also, try adjusting the envelope parameters to alter the filter behaviour. Here I’ve increased the attack, decay and release, and reduced the sustain, creating an interesting ‘wah-like’ effect.
Finally, try adding a little Resonance to make the Cutoff Filter more prominent.
Another way to get some really creative sounds is by routing a sidechain input into a soft synth. I love this technique for generating patches that I would never come up with myself, where the input signal directly affects the sound and creates something new.
Add a new software instrument track and load up Logic’s ES 2 synthesiser, which allows a sidechain input.
Straight away, go to the top-right corner of the synth and choose the audio loop as the sidechaining source.
You can also bypass all of the modulation effects for now except for the first, as we’ll be configuring our own settings here shortly.
Click and hold on the MIDI chords that you already recorded (for the EXS24), hold ‘Alt’ and drag the region to the ES 2 track. This will quickly and easily create a copy - handy!
We can continue using the default patch for now, as the saw waves will help to clearly demonstrate how the sidechain signal can influence the overall sound.
Now we need to tell the ES 2 to listen to the sidechain input. Head back to the modulation settings and you can see that the Target is currently set to ‘Pitch 123’ - this means that envelopes 1, 2 and 3 are configured to be modulated. We can change this to any parameter within the ES 2, but let’s stay with pitch for now as it will make the effect more obvious.
Next, switch the ‘via’ routing to ‘Off’ as we don’t need it for now, and choose ‘SideCh’ as the source (‘SideCh’ is simply short for ‘Sidechain’).
Increase the modulation level during playback to hear how the sidechain input source (aka our drum loop) is being used to modulate the pitch of envelopes 1, 2 and 3.
We can adjust the modulation level depending on how much we want the envelopes to respond to the loop. Used subtly, this minor pitch shift can create an interesting sense of movement in what was previously a very conventional sound.
Try experimenting with the modulation source e.g. Cutoff, Glide, Pan etc. for even more effects, and you can even use multiple modulations for endless variations!
EVOC 20 Polysynth
Another frequently overlooked instrument is Logic’s built-in vocoder, the EVOC 20 Polysynth, which also features a sidechain input. The EVOC combines a vocoder and a polyphonic synthesiser (as the name suggests), enabling the creation of classic vocoder sounds triggered by the human voice. However, you can use any audio to trigger the synthesiser, which is where things get even more interesting.
I could go into great detail regarding the functionality of this instrument, but I’ll keep things straightforward to get you started experimenting with the sidechain input. As it’s a synthesiser, it acts in a very similar way to the ES 2 above, where we modulated the instrument with the sidechaining input.
Let’s start by calling up an instance of the EVOC 20 from Logic’s instrument list.
Rather than record in another set of chords, hold ‘Alt’ and drag the MIDI chords we generated earlier onto the new EVOC track to copy the region.
If you hit play you’ll hear the vocoder’s default synth patch, with no sidechain trigger acting upon it, so let’s set it up.
Just like the other plugins and instruments, click on the sidechain input dropdown and select the original drum loop as our input source.
In the Output Parameter section on the right, choose ‘Voc’ as the monitor source.
This refers to ‘Vocoder’ which will allow us to hear the overall effect. ‘Syn’ stands for ‘Synthesis’ meaning you’ll hear only the synth, and ‘Ana’ refers to ‘Analysis’ where you can monitor the analysis signal i.e. the input source (in this case, the drum loop). If you start playback this time round, you’ll hear the drum loop triggering the synthesiser.
To modify how the audio signal is analysed and used by the EVOC, we can use the Sidechain Analysis Parameters. You’ll see in the centre of the plugin that there is a range of envelope bands between 80 and 8,000 Hz. An envelope follower is programmed to control each band based on the sidechain input.
Much like a compressor, the Attack knob controls how fast the envelope followers react to rises in the input signal, and the Release parameter determines how quickly the envelope followers react to falls in the signal.
In other words, the faster the attack and the release, the more precise and articulate the sound, but this all depends on what the input is. Adjust these settings to taste depending on what you’re looking to achieve. As we’re using a percussive loop, I’ve kept a fast attack setting and a tight release.
We can use the Frequency Parameters in the centre to control how much of the drum loop is allowed through. For example, let’s cut the lows up to 400 Hz so that the synthesiser only responds to frequencies above 400 Hz in the audio. The EVOC reacts to different frequencies in different ways, triggering the various formant ranges, so feel free to experiment!
Back in the Sidechain Analysis Parameters, a really cool function is the Freeze tool. During playback, you can click this button at any point to capture the characteristic of the input signal at a specific point in time, meaning that the filter shape will be fixed.
This is really useful if there is a particular part of the loop that stands out, as you can apply the filter shape to the whole loop. You can also change the number of frequency bands that the filter bank uses. Essentially, the more bands the EVOC uses, the more precisely the sound can be processed.
Finally, go experiment! Play around with the formant parameters to see what kind of sounds you can generate. Try using alternative audio samples for the sidechain - vocals can sound particular other-wordly! There are also a number of presets included that are tailored for sidechaining, so make sure you try these out.
If you’d like to find out more about what the EVOC is capable of, I recommend Logic’s online manual as you can delve as deep as you like.
It’s worth spending time exploring additional instruments and effects in Logic that offer a sidechain input. For example, other synths, such as Logic’s built-in Sculpture, can generate some very unique timbres, perfect for experimenting in any kind of electronic music. The Ringshifter, too, can generate some super interesting sounds!
After searching online and within Logic’s official manual I couldn’t find a definitive list of stock plugins and software instruments that feature a sidechain input routing, so I decided to make one for reference. Feel free to check out the article for a full breakdown.
I hope this overview of sidechaining alternatives in Logic was useful and that it helps to inspire some out-of-the-box creative effects!
If you have any questions or just want to get in touch, let me know in the comments below or email me directly at firstname.lastname@example.org.
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