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Making a Polyphonic Arpeggiator in Ableton Live

Using the expression control MIDI device to create a polyphonic arpeggiator in Ableton Live 11
Generative art by Ana Ulin

Ableton Live offers an exceptionally good playground to mess with arpeggiator ideas. The built-in MIDI effects as well as the many available Max for Live devices are great for anyone who wants to create their own arpeggiators. The focus of this post is to create what you would call a polyphonic arpeggiator in Ableton Live.

What is a polyphonic arpeggiator?

In the context of this post, a polyphonic arpeggiator refers to a device that has multiple arpeggiator "voices". In a classic arpeggiator, all incoming notes are treated the same and a pattern is generated using their combination. In contrast, a polyphonic arpeggiator treats each incoming note separately and generates different patterns for each note.

Creating a three-voice arpeggiator in Live

Now let's see how we can make a polyphonic arpeggiator in Ableton Live. To keep things simple, we'll consider a three-voice arpeggiator. To follow along you will need an installation of Ableton Live 11 Suite, mainly because we are using the expression control device available in that version.

Step 1 - Set up three arpeggiators separately

Load three MIDI tracks and program three arpeggiators using MIDI effects and M4L devices. Make sure that it's not too complex and has a pinch of randomness.

Several devices you can use for this are the inbuilt arpeggiator, note echo, random, and the arpeggiator from the Max for Live Essentials pack (a free download from the Ableton website). You need to set up these three separately so that you can tweak each one to your liking.

Step 2 - Combine them in a MIDI effect rack

After you are happy with each of the three arpeggiators, combine them in a MIDI effect rack. For this, get a blank MIDI rack, make three chains, and copy in the devices you made.

Step 3 - Make it polyphonic!

In the MIDI effect rack, switch to the chain select editor view using the chain button. Divide the three chains among the 127 divisions. You can do this by dragging the ends of the chains. (Or right-click and select distribute ranges equally). Now the MIDI rack will only play the selected chain, which is denoted by the light blue chain selector strip.

Chan selector

Now add an Expression Control device (from MIDI effects) before the rack and do the following.

  1. Change the dropdown of the first chain to Incremental
  2. Set the amount to 44 (because there are 3 chains -> 128/3 is approximately 44)
  3. Click Map. While the map button is blinking, click the chain selector
Expression control

This maps the expression control to the chain selector. The arpeggiator should now react differently to each successive note. Add a hint of delay to make it sound more interesting.

Your final device chain should look like this

Expression Control >> Arpeggiator rack >> Instrument VST >> Audio Fx


Here's a demo of what polyphonic arpeggiators sound like. Note how each successive iteration of the arpeggio is different from the previous one!

The above demo is from the MIDI rack "Tiny Dance Party". You can check it out on Gumroad!

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