Line6, can we get a definitive solution on how to calibrate the POD GO built-in expression pedal? My unit covers the entire range from 0% to 100% in the MIDDLE THIRD of the physical pedal position. In other words, I'm at 0% with the pedal all the way back. As I move the pedal forward, it stays at 0% until I'm 1/3 of the way through the full pedal throw. Then it climbs from 1%, and I hit 100% at 2/3 forward, where it stays until all the way full forward.
The sensor for the expression pedal is an optical IR emitter/sensor pair (not a mechanical potentiometer). The emitter/sensor pair sit side-by-side facing a small shiny metal plate attached to the underside of the pedal. When the pedal moves, the shiny plate changes the angle of reflection of the emitted IR light, in turn changing the amount of light reaching the IR sensor. A nice design with no moving electrical parts.
BUT, there must be a way to calibrate this system, as the amount of light reaching the sensor will vary depending on several things not related to the position of the pedal:
1. The reflectivity of the shiny plate will vary depending on exact installation angle, accumulated dust, and age.
2. The amount of IR emitted will vary by LED. Even the tightest tolerances have variations.
3. The amount of IR received will vary by sensor. Even the tightest tolerances have variations.
Pics attached, just for reference. The extra chip on the left in two of the pics is a replacement emitter that I was installing, since the stock emitter in my POD GO failed during an outdoor gig on a hot day. The replacement emitter works great, but it needs calibrating.
