How do I MPE?

Question

Just bought myself a Sensel touchpad controller and am trying to wrap my brain around this whole new world of MPE and how it relates to Kyma. I have a few questions:

• Can I use KymaConnect or do I have to plug the Sensel directly into the Pacarana?
• Is there a sound in the library that utilizes MPE so I can see how my Sensel is interfacing with Kyma?
• When using MIDI voice how do I get polyphonic aftertouch?

Thanks!

Answer 1

KymaConnect passes MPE MIDI commands correctly to and from the Pacarana without modification unless you have explicitly set some of its MIDI filtering and channel mapping, which is disabled by default. So it is "MPE neutral".

MPE though expects a  device in the set up that is responsible for sending the correct commands to the MPE controller to configure it for proper operation. One of the most important parts of this set up information is informing the MPE controller how many touches (voices) the sound supports. If the MPE controller is configured for more touches than the sound generator expects there will be missing touches (notes). A few MPE controllers provide all the necessary set up through their preferences or configuration screens but many do not and must be set up remotely through MPE configuration MIDI commands.

Typically the command device that sets up the MPE controller is a central application like a DAW. The Kyma application in conjunction with the Pacarana serve in this capacity in a Kyma set up.

For this to work though Kyma needs to know that it has an MPE controller attached. There is not a "are you a MPE controller" command in the MPE standard. This means that the presence of a MPE controller must be detected by more indirect means such as through looking for specific SYSEX responses to SYSEX queries or other means.

Kyma does this sort of thing to recognize the Linnstrument, and Roli Seaboard when it is USB connected direct to the Pacarana. It does not currenty recognize the Sensel.

Once Kyma has determined that it has a MPE controller sending MIDI it automatically changes how the MIDI Voice sound treats incoming MIDI. It supports MPE X-axis commands mapped to per-touch continuous pitch change, MPE Z-axis to continuous !Velocity, and MPE Y-axis to continous !Timbre. So it more or less just works as expected, provided the Kyma Sound was set up to take advantage of those parameters.

Polyphonic Aftertouch is not part of the MPE specification. It is not sent for MPE touches. MPE uses one MIDI channel per touch and sends Channel Aftertouch for the Z-axis. It does not use Polyphonic Aftertouch.

Comments

Thank you for the thorough answer. I feel like I have a much better understanding of MPE now. I guess I'll have to remain vanilla MIDI for now, although the Sensel does allows you to assign CC numbers to various parameters, which I think will come in handy. Cheers!

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Thanks Douglas, for that detailed answer.  This helps my understanding of the MPE standard and SSC's implementation.

I thought I would add my follow up questions that are centered around the MPE standard and the specifics of SSC's implementation here rather than start a new post.  


If an MPE controller is ported through the DAW rather than via Kyma Connect or the USB socket on the Paca* does the 'handshaking' protocol get filtered from kyma even if all sys ex data is not filtered at any of the software or hardware stages.    I am wondering if the 'handshaking config' might timeout due to latency as a possibility.  

What I notice is sometimes my Linnstrument works exaclty as expected when running via a DAW Midi track and sometimes kyma loses the MPE midi channel modulo (the sound only responds on midi channel 1).  Even though the Show Midi Message panel in kyma sees all the expected messages and the rotating channels per voice.

Anyone have any thoughts as to why?

Thanks
Rafe

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It is difficult to answer as it would probably depend on specific implementation details in the Linnstrument and Paca/Mara. MPE itself does not use SYSEX. My mention of SYSEX above was an example of how a host might try to determine if a specific MPE controller were connected. I do not think that is the case with Kyma but only SSC could answer that. My suspicion though is that filtering or timing is not the issue here.

If the Paca/Mara is no longer responding to MPE events (e.g. ignoring commands other than on its assigned channel, usually the global channel) then that suggests to me that it has returned to "normal" MIDI mode and is no longer in MPE mode. In my experience this is normal when a new Sound is loaded. If that happens then the MPE set up sequence/handshaking would have to be repeated.

The back and forth between the MPE controller and host requires a bidirectional MIDI connection. This can be sometimes problematic in a DAW due to how DAWs manage MIDI tracks, MIDI pass-through, etc. Furthermore the DAW would have to provide a pathway for the Paca to send MIDI to the Linnstrument. How one would set up such a thing is pretty DAW specific.