expression pedal

An expression pedal is a foot-operated control device that works like a foot-based control knob, on the same concept as a volume pedal or a wah¹. It generates no audio itself, but instead sends control signals to amps and effects units to manipulate tone and effects in real time². It connects to a compatible effects device and can be assigned to change certain parameters, for example manual control of delay time, delay repeats, modulation speed, depth, or extent of pitch shifting³. It does not create or contribute any effect or sound in and of itself, and the controllable parameters depend on the connected device's feature set⁴. Most use TRS wiring, but some units require specific polarity or resistance ranges, such as 5k-50k ohms, to achieve a full sweep response².