So with all this talk about polyphonic expression in Live 11, what about Ableton’s own hardware? It turns out existing Push and Push 2 hardware transforms with the new software.

It works like this: connect a Push 1 or Push 2 to Live 11, and enter the Setup menu on the Push hardware. You’ll find a new parameter called Pressure, which you can switch from ‘Mono’ to ‘Poly.’ (I’ve confirmed this with Ableton.)

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Note Expression from Push can be played right into Clips and played back or edited.

You always had pressure sensitivity on Push, but pressing with any finger impacted the whole instrument you were playing. With Poly Pressure on, Push senses and transmits individual pad pressure – so if your left-hand thumb presses harder and your right-hand index finger lighter, those register independently.

That has instant benefits inside Live 11, too. You can record that poly pressure data into Live. You can edit it and play it back inside Clips (in the new Expression tab). You can use MPE-capable instruments – including now Ableton’s own Sampler, Simpler, Wavetable, and Arpeggiator. You can play third-party instruments that support MPE via Live, at least as far as playing them with poly aftertouch. And you can map that pressure to other parameters, using the new MPE Control device.

Here’s a demo by Andri Søren:

Okay, eagle-eyed readers may have noticed me dancing around terms there. There’s MPE – MIDI polyphonic expression. (An early name for this was even “expressive MIDI,” before someone worried that meant existing MIDI wasn’t expressive.) And then there’s an older format, polyphonic aftertouch.

What the heck is the difference? Well, let’s back up to channel aftertouch.

Aftertouch is continuous pressure applied after you play a note event, and before you release it.

Channel aftertouch is how most keyboards and other devices typically implement aftertouch. It’s sent for the whole channel at once – so even if you play a chord, there’s just a single aftertouch message sent across the whole channel. Let’s say you play a string chord, for instance – if you press down on the keys after you play, the whole chord will swell at once, but you can’t apply more pressure to the top note to bring it out. It’s the same with other channel messages, like pitch bend – which is why the pitch wheel impacts all the notes you play at once.

Polyphonic aftertouch makes the aftertouch messages apply to individual notes – each finger’s pressure is sent separately.

MIDI polyphonic expression is effectively a superset of that notion. Any parameter you send can be sent per-note. It’s a simple hack, too – it just uses separate channels for each note so that channel contains the associated control messages.

The relevance to Push / Push 2 here is that you can apply pressure to individual pads, but not per-note pitch bend, for instance – there aren’t hardware sensors on the Push to even accomplish that. The pitch and modulation strips work as channel-wide controllers, just as they always did.

I fantasized that I would write this post and it would be really short, but … yeah, there’s what happens if you explain everything, for any of you who made it this far.

For more on Live 11: