- Connect multiple MODEL D units (MIDI OUT of first to MIDI IN of next).
- Ensure all MODEL D units have the same MIDI Channel number set.
- Turn the MODEL D power on.
- Within the first 5 seconds, press the A-440 switch 4 times to enable Poly Chain mode (Power LED flashes fast four times).
- Ensure Poly Chain is OFF for all units except the first master unit.
Source: Minimoog Model D — model-d-qsg-ww (manual)
