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Microtones, from OM to Sibelius, or Live

Does anyone know how you might send out midi from Open Music to an external synth/sequencer (for example Ableton Live) AND be able to maintain microtonal information in tact?

I know the bm Microton is specifically designed for this goal inside OM, but I need to develop my microtonal material in an old fashioned arrangement (Sibelius/Ableton Live). I also know it’s possible to export the xml of material from OM - for example to Sibelius, then the score displays correctly but again, I can not hear the micro tuning as Sibelius is not interpreting it.

Simultaneously, it would be great to send Sibelius midi arrangement back to bm microton, but when I do, again, the microtonal info seems lost!


The difference between bmMicroton and other solutions is that it doesn’t rely on MIDI, specifically.
The midi protocol is not designed to handle note values apart from 0-127 integers.
This is why Microton relies on OSC messages between OM and Max. So to reproduce this with Ableton Live you’d
probably need MaxForLive on your machine, and build a small device to receive the midicents from OM through udpreceive
or something similar.

If you reconsider Sibelius, actually if the display of microtones is fine, you just need to use a plug-in (included in both Sib 6 and 7) that will change the pitch bend of the notes according to their accidental symbols. Only thing, as the plugin’s name is “quarter tone playback”, you probably won’t get more precise microtones.


There seem to be some issues with midi playback in OM 6.7. However, you can playback midi correctly as long as you are in an editor (chord-seq, etc.)
OM automatically sends 1/4 and 1/8 tones on an offset channel.
For instance, if you have a chord-seq where all chords are in channel 1, 1/8 tones will be sent on channel 2, 1/4 tones on channel 3, 3/8 tones on channel 4.
So, if you want to play 1/4 and 1/8 tones on another midi decive (say, in Ableton Live) you need to:

  1. configure your midi output (see this post http://forumnet.ircam.fr/user-groups/openmusic/forum/topic/how-to-set-om-playback-through-external-soft-synth-on-macos-x/?lang=en)
  2. in the OM preferences window, check the box “Auto microtone bend” and click Apply
  3. in your software instrument/sequencer (Ableton Live for instance): create four instances of the same synth (midi instrument) that will each recieve midi only on channels 1, 2, 3, 4 respectively from the output that you specified in step 1 above (IAC Driver Bus 1, for example).

Hope this helps

I keep selecting portmidi in OM 6.9 to connect to midi programs. It would be great to use Ableton Live 8 for microtonal playback (i don’t have Max for Live). Using pitchwheel, I’m able to retune Simplesynth, while Live keeps playing only halftones from the same IAC-bus. I have not yet understood this difference.
Could I make my own Max-patch with fluidsynth, connected with portmidi (like a homemade bm-microton), or would you recommend other programs playing 128 midi channels?

Thanks for info guys, this thread helps me to send midi from OMusic to Bitwig studio!!

To help others, here’s is how I did it (it should work for anyother DAW). I did it with a hardware device with MIDI Thru On that I can use to bring the MIDI information back in my DAW. You could probably do it internally with some “inter-midi” application but I didn’t know the steps… so I use a “external” solution and it’s works really great.

So, here the steps :

  1. Open Music Preferences, MIDI tab, click to Ports Setup and in Output Devices choose one of your synthesizer or MIDI controller. (for me it’s Arturia Keystep 37 for example). This synthesizer or MIDI controller MUST HAVE MIDI Thru option ON. So, OpenMusic will send MIDI info to this hardware device and this device will duplicate all MIDI infos on his MIDI out port.
  2. Now, route this MIDI information back to your computer with anyother MIDI device (I use the MIDI ports directly on my soundcard Steinberg UR-44). Concretely, I put a MIDI 5 pin cable between the MIDI Out of my Keystep 37 to the MIDI In of my soundcard.
  3. In my DAW, I created an instrument track (with any VST Soft synth or other samplers) and duplicated it 4 times. So you will have 4 instruments tracks.
  4. On track number 1, choose your “MIDI device Channel 1” for the MIDI input. (for me it’s Steinberg MIDI In - Channel 1).
  5. On track number 2, choose your “MIDI device Channel 2” for the MIDI input.
  6. On track number 3, choose your “MIDI device Channel 3” for the MIDI input.
  7. On track number 4, choose your “MIDI device Channel 4” for the MIDI input.
  8. On OMusic, open the Tutorial number 10 patch, named MIDI Microtone Setup. Right-click on the first pitchwheel object and choose “Eval box” to Evaluate it. This will send to your DAW all the information you need to de-pitch the different channels (read the documentation of Tutorial 10 for all the details…)
  9. Now, BE SURE to “Record Arm” all your 4 instruments tracks (to hear something) and play the Chord-Seq at the bottom-left of the patch (double click the object and choose play ), you should ear all the microtones. :slight_smile:

Hope it’s working for you. To “retune” the 4 channels, you can use the “Pitchbend setup reset” on the patch. There’s is also a Pitchbend setup range =1 if your VST instrument have this settings (instead of a pitchbend range = 2).