Set GLB-8 [MIDI] → Clock Source to EXTERNAL, then send MIDI Clock from the source into the Prophecy's MIDI IN. If the arpeggio still does not start, check its keyboard scan zone.
Try these checks
- Connect the clock source's MIDI OUT to the Prophecy's MIDI IN.
- On the Prophecy, open GLB-8 [MIDI] and set Clock Source to EXTERNAL.
- Start the external clock source and play a key inside the selected arpeggio keyboard scan zone.
Diagnose it
Is the Prophecy set to EXTERNAL clock?
Yes: Check that the source is actually sending MIDI Clock to MIDI IN.
No: Set Clock Source to EXTERNAL in GLB-8 [MIDI].
Does a held key fall inside the arpeggio keyboard scan zone?
Yes: Check the external clock output and physical MIDI cable.
No: Adjust the pattern's keyboard scan zone to include the played key.
What should happen
The arpeggiator follows the received MIDI Clock tempo.
Why this happens
Korg defines EXTERNAL as the mode in which incoming MIDI Clock controls the arpeggiator. Its troubleshooting table also points to Clock Source and keyboard scan when an arpeggio does not start.
If it still doesn’t work
Check the connections and settings described above. If your device behaves differently, email us with its model, firmware version and the steps you tried.
All Prophecy fixesMore about Prophecy
Similar symptoms on other gear
These guides cover other models. Use the instructions for the device you are setting up.
Sources & review
Sources reviewed: . Documentation does not replace a physical hardware test.
- Prophecy Parameter Guide · Korg · last checked 2026-09-26 · Open PDF
Sections reviewed: GLB-8, p. 139; Troubleshooting, p. 175.