Local Control Off/On Local Control On or Off is used if your controller keyboard(s) contain sound generators. Choosing Local Control On and playing the MIDI controller device (usually a keyboard) audibly triggers the device’s internal voices and sends the corresponding data out the MIDI Out port. Choosing Local Control Off and playing the keyboard of the MIDI controller device does not audibly trigger the internal voices but does send the keyboard data out the MIDI Out port. Choose Local Control Off when you want to play modules from the master keyboard but don’t want to trigger its internal sounds. This can sometimes eliminate a problematic flanging or doubling effect.