Logic Pro Tutorial – Secondary Modulation with EXS 24
I just completed a series of videos on the new Analog Strings instrument from Output and was blown away with the incredible sounding modulations created with their Flux feature. This type of function is often referred to as secondary modulation: modulating the modulator. The rhythmically complex patterns that result are very compelling. How can we emulate this sort of vibe with Logic Pro’s plug-ins?
Secondary Modulation with EXS 24
In this Logic Pro tutorial I’ll show you a way to generate an interesting rhythmically rich modulation routing using our venerable EXS 24, along with the new “learn plug-in parameter” mapping function in the Modulator plug-in.
Start with some Sustained Chords
To start with, I’ve programmed up a series of sustained chords at 106 bpm using the EXS 24 factory preset called Choirpad MW, found in the Synth Pad menu in the Synthesizers category. I put a simple drum loop underneath to establish the pulse. Here is what it looks and sounds like:
EXS 24 Setup
In this exercise, we will start by modulating the filter cutoff with LFO 2. This routing is already setup in the fourth row of the EXS 24’s modulation matrix. The rate is set to be controlled, or modulated, via the mod wheel. Remove the mod wheel control by clicking on the “via” field, and choosing the dotted line instead of Ctrl #1.
Next, bring the two ends of the amount slider together, so that the range of filter modulation is fixed at one value. I chose a value of -30.7%, slightly below the detente value.
Modulator Plug-In Set Up
At this point, there is no filter modulation taking place yet. We will set that up externally with the Modulator plug-in. Click in the Channel Strip’s MIDI FX slot and instantiate the Modulator plug-in. We will use the LFO here to modulate the rate of the EXS 24’s LFO 2. And we will use the Modulator’s Envelope section as the secondary modulation to add rhythmic variables to the LFO rate.
Sound complicated? It isn’t really that bad. To better understand the process, start by turning off the Modulator’s Envelope section and focus on it’s LFO functions. Set the trigger mode to Free, and chose the saw-tooth wave shape. Put the rate at 1/8th notes, and for more of a stepped sound, reduce the Steps per LFO cycle slide to a value of 12. In the bottom part, leave the Output level at unity, and push the Offset slider above its unity setting, to a value of about 22%.
And now the most important part, we need to tell the Modulator plug-in where we want it to direct this activity to. Click in the To field in the lower half of the window, and choose – Learn Plug-In Parameter – from the list of available destinations. Before doing anything else, click on the LFO 2 rate knob in the lower half of the EXS 24 interface. This will map it as the destination for the values the Modulator’s LFO is generating. As soon as you release the mouse, you will see the LFO 2 rate knob dancing to the Modulator’s LFO values. It should look and sound something like this:
Setting up the Secondary Modulation
So far we haven’t done anything particularly extraordinary yet. Now comes the interesting part. Enable the Envelope section of the Modulator plug-in. In the upper envelope section, set the Delay to 0.00 ms. The attack to 840 ms. Hold at 100 ms, and release at 16.0 ms. Put the trigger mode at LFO and adjust the ENV to LFO rate to a value of about -20%. Set the Steps per ENV Pass slider to 15, and adjust the ENV to LFO Amp knob to -10%.
In the lower half, reduce the output to 36% to limit the range of the secondary modulation. Leave the Offset knob at zero. And finally, click in the “To:” field, and as we did above, choose the – Learn Plug-in Parameters – function followed by a click on the EXS 24’s LFO rate knob. With both the LFO and Envelope sections enabled, it should look and sound something like this:
You can generate a lot of interesting variations and rhythms with a setup like this. Here’s an example using a slower sine wave based LFO, coupled with an Envelope using a shorter attack time and faster Env to LFO Amp value that creates an interesting glitch style effect.
Thanks to Output for inspiring me to explore this direction using Logic Pro’s plug-ins! Now, I’m not saying this type of routing is as full featured as the Analog String Flux controls; it’s not. But there is still a lot of life and creative mojo to be had using Logic Pro’s beloved and time-tested stock tools.
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