I have recently acquired a TC Electronics Tube Pilot guitar effect pedal.
While exchanging the vacuum tube in it, I noticed that there was a 22k ohm variable resistor on the board. Can anybody tell me what the function of this resistor is? As far as I can tell, I only hear a volume difference when I adjust the potentiometer.
Edit: I've added an image to the question.
The resistor is labeled 'VR1'.