I recently got a Russian Big Muff Pi, the black one with greenish/yellow printing on it, and seem to have almost the same problem.

When I switch it on, the LED lights up nice and bright (tried two brand new 9V batteries, this pedal has no power adapter option) but unless all three knobs are turned up 100%, it cuts the signal to practically nothing, and there’s no distortion to be spoken of. Even maxed out on the knobs and with every imaginable combination of settings, it still puts out next to nothing.

Tried it with my ’66 Duo-Sonic, two of my Jagmasters, my Epiphone SG, and the guitars seem to make no difference. Played it through my half stack, and my tiny little Danelectro Honeytone amp, same business no matter what I try. Just no distortion, and barely audible in comparison to my amp’s clean channel.

I listened to the audio samples on the Musician’s Friend site, and it was Muff-city, really nice. I seriously think there’s something wrong with this box, but don’t know where the trouble would be stemming from.

Any suggestions?

(Attached a picture of the box, I’m new to this forum, and not a computer genius, so if it doesn’t show up I apologize.)