My friend Huwberry (a member of the forum) lent me his EHX Bass Micro Synth for a gig, of sorts. However, he mentioned that the filter seep wasn't working, so I looked at the manual and saw that you could adjust the input gain on the bottom of the pedal using a small screwdriver. That fixed the problem.
I also opened it up to have a gander, and saw that there was a second potentiometer, the same as the input gain one. I couldn't figure out what it did. It seemed to make no difference to the sound.
What does it do?