@ulrik I don't have a clear example right know but the Synth.PlayNote(); works when the Arpeggiator is inside a ChildSynth, but if you try the Message.setNoteNumber(); the Arpeggiator will work fine outside, the problem here is that you want to play a chord but if you review the API the Message and MessageHolder functions have things like MakeArtificial(); so maybe you want to start there.