Korg PA4X Quick Start Manual page 47

Playing and controlling the Sounds |43
Using the joystick
Moving the joystick left of right usually changes the Sound's pitch. Moving
it forward usually trigger modulation, but this depends on the selected
Sounds. With the electro-mechanical organs, pushing the joystick forward
changes the rotary speaker's speed. What it does when pulled back depends
on the selected Sounds. Just experiment!
Using the ribbon controller
Sweeping left of right on the ribbon controller usually changes the brilliance
of the Sounds and/or the pitch, but how it works depends on the selected
Sounds.