Enter Beats Mode

1. Press and hold both the Master button and the Edit button.
2. The Beats menu will appear and the Enter LED will be flashing.
3. Press the Enter button to Start the beat or song.
4. To exit, press and hold both the Master and Edit buttons again to return to the main screen (the beat continues playing). To turn off, return to the Beats menu and press Enter.

Source: Planet Phatt — e-mu-planet-phatt-operation-manual (manual)