The upper wheel is double and originally used to tune in the stations. One wheel for AM, one for FM. I have kept the strings and stuff, but replaced the vari-caps with potentiometers connected to the computer trough AD-channels. At the moment these are not used but in early testing I used them to control filters in the Reason software-synth. I will eventually take them into use again, maybe with one of them as a radio-simulation, letting you scroll trough radio-noise and old time radio programs.
The lower knob is the original treble control. Now it is used to control the feedback level to give beautiful guitar like feedback.