Polyphonic aftertouch supported?


I’ve read MPE is supported in HAPAX, but I’d be interested in knowing if midi polyphonic aftertouch is supported as well (not channel pressure but actual note aftertouch messages). I actually sent this question to Squarp but then thought I’d put it here so that others can read the response as well. Sorry Squarp for duplicating questions :S


Good question. Interested in this too.

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not currently supported.

poly at is not really used in MPE… as it uses ch pressure on different midi channels…


thanks for the answers.
not sure if I understood you right @thetechnobear. MPE uses several channels for a single instrument yes (and that is how it achieves multiple per-note modulations), but polyAT (polyphonic aftertouch) is different as it simply uses “note aftertouch” messages from the original midi specification and keeps a single channel per instrument.

in the past I was in conversations with squarp asking for polyAT support in pyramid, but they said pyramid was not powerful enough to handle that many messages generated with polyAT. of course hapax should be capable of that if it can handle MPE, but I wonder if hapax currently supports that or will support it in the future.

tha tricky thing with polyAT I guess is editing AT curves per note after these are recorded (just like for MPE but simpler as there’s only one parameter in polyAT). but I would be happy enough if editing is not possible but polyAT messages are recorded and played back (like currently for MPE).


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Hi @frederic.font ,

There is currently limited support for PolyAftertouch.

I would be happy enough if editing is not possible but polyAT messages are recorded and played back

That’s precisely what should be possible in hapaxOs v1.0.

We have much more on our roadmap, and improved PolyAT support is one of them, and seeing the popularity of the Hydrasynth series alone, will be a worthwhile endeavor for sure.



oops, my mistake… I didn’t see anything when editing so assume they were not being recorded…

is this in poly mode? or are you including as part of mpe? (or both?)

Great to hear that PolyAT is recorded at least. Encouraging also to hear that improved support for it is on Squarp’s roadmap. Good stuff!

One additional question on the existing functionality of recording Poly AT.

Is the Poly AT on playback exactly the same as it is when recorded? Or is it kind of ‘summed’ to Channel Pressure?

I’m not too fussed with editing the data either. Having Poly AT recorded and played back as performed though would be great. Is this how the existing functionality for Hapax works?


Awesome! I also have a Hydrasynth indeed :slight_smile:

This makes the Hydrasynth player in me VERY happy.

Hydrasynth users should note that Hydrasynth in MPE mode also sends MPE, it isnt a receive-only MPE implementation. So even if the Hapax did not support PolyAT midi messages, you could still use MPE mode to record per-note aftertouch from your Hydrasynth into the Hapax.

Since Hydrasynth keyboard etc hardware doesnt do the other MPE dimensions other than pressure(aftertouch), there is no other particular advantage. But in future Hapax firmware, when Hapax allows MPE data editing (or maybe also MPE algorithmic generation or MPE midi effects if we are lucky with what Squarp develop for us in future), you could program per-note pitch-bend and MPE Y into your Hapax patterns and then have Hydrasynth respond to them.

It is great for Hapax to support PolyAT as well as MPE, for maximum compatibility with all controllers and synths. It is a great time to be alive with all these expressive per-note options in controlls, synths and now a lovely hardware sequencer. Also a good thing that Hapax has multiple midi output ports, since MPE uses up so many midi channels.

I’m not sure if I’m doing something wrong, but my Hapax doesn’t recognize the polyAT messages sent by my Hydrasynth. I tried this with my Hydrasynth connected by USB and DIN midi. I am 100% sure the Hydrasynth DOES send it, as I can capture it in Ableton.

It does work when I set the Hydrasynth to MPE mode, but that has some other drawbacks (like it uses multiple midi channels instead of one, so you need to use a separate midi port for just the Hydrasynth).

Or did I overlook something? @Thibault_Squarp ?

Then it might be a bug on our part. I’ll have to get back to you on that.
Improving PolyAT support is already on our todo list, but I’ll bump that further up in it.


Thank you!

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Looking forward to receive my 2nd-batch hapax and test the polyAT/mpe stuff :slight_smile:

I just received the hapax and started playing with it (firmware 1.10). Polyphonic aftertouch/channel pressure messages are correctly transmitted when I’m playing my controllers but these do not seem to be recorded (and these are not set to “ignored” in MIDI settings). Does anyone know if this needs to be enabled somehow?

Are you sure it is receiving polyphonic aftertouch? Mine doesn’t. It only receives pressure from my Hydrasynth is in MPE mode, not regular polyphonic aftertouch. Channel aftertouch does work though.

Try shift+live for midi input/output monitoring.

In the midi monitor polyAT messages are not shown (but channel pressure is indeed), however if I play my polyAT-capable controller which sends MIDI to Hapax and then Hapax sends the midi to a polyAT-enabled synth, I can see that the synth indeed receives the messages and I can use full expressivity. However, when recording the sequence, polyAT messages do not seem to be recorded. Same thing seems to happen with channel pressure messages, these are transmitted to the synths but not recorded (?). @Thibault_Squarp

This is something we’re working on improving soon.


Are you sure you are not sending it directly to the synth (without Hapax in between) as well?

@Maarten yes I’m sure.

@Thibault_Squarp therefore my observed behaviour is to be expected for os 1.10beta?
I understood from above in this thread that recording of polyAt was already on 1.0.