This video demonstrates using the expression pedal connected to adjust a parameter, the aux switch is not being used.
The expression pedal jack settings are described in the QRG here: https://cdn.eventideaudio.com/uploads/2024/10/Knife-Drop-QRG.pdf
If you’d like to use the expression pedal and also change presets, you’ll need to use a MIDI controller. Let me know if you’d like any suggestions.
