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Playback in OM 6.16

I’ve installed OM 6.16 on a new laptop, a MBP running OSC 10.15.3. I’d like to just hear some playback of chord objects in some simple patches but when I hit play I get the error message:

OM > “PortMIDI ERROR: port 0 is not connected. Check MIDI preferences to connect MIDI devices ?”

Any advice on what to do to get playback of the basic midi piano sound? I thought this used to work on older version of OM, not sure what’s changed in 6.16 or what I need to set up in preferences to make it work.

Or, any advice on microtonal players for OS 10.15 and OM 6.16?



Have a look at



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Brill, thanks Jerome.

Another little thing if someone is still following:

In OM 6.16 I can only playback a chord (via Midi IAC -> Logic) from the patch when the chord is in ‘chord’ mode, not ‘arp up’ etc. If I try within the chord editor it plays back fine in any mode, but when back in the main patch, nothing. I notice that the little play icon also doesn’t show in the chord object if I don’t have a chord in ‘chord’ mode.

I know that playback behaviour has changed a little over different versions of OM but would just like to check how it should work, as I’d like to be able to quickly play chords as either chords or scales as I like (my patches are often collections of many chord objects that I listen and compare etc).


Sorry this is an unfortunate bug. :face_with_raised_eyebrow:


I have the same problem as you with a MacBook Pro running OSC 10.13.6 with the OM 6.16. Same error message and no sound when I am running the midi ?
Catalina does not work on my OSC, any other solution ?

Thanks !


I think you need to create a MIDI IAC Bus on Audio Midi Setup of your Mac (search online for that), then in OM it should appear in: Preferences > MIDI > Ports Setup.

Once you define IAC Driver Bus as a midi out then you can use any other DAW or similar to receive the incoming midi for playback on whatever sound you like/have