The Pitch Bend wheel is used for "bending" the pitch up or down. The Modulation wheel can be used to apply various modulation while you are playing the loop. Virtually all MIDI keyboards have Pitch Bend and Modulation controls. Dr.Rex also has two functional wheels that could be used to apply real time modulation and pitch bend should you not have these controllers on your keyboard, or if you aren't using a keyboard at all. The wheels mirror the movements of the corresponding MIDI keyboard controllers.
The Range parameter sets the amount of pitch bend when the wheel is turned fully up or down. The maximum range is "24" (=up/down 2 Octaves).
The Modulation wheel can be set to simultaneously control a number of parameters. You can set positive or negative values, just like in the Velocity Control section. The following parameters can be affected by the modulation wheel: