I got a chance to try a few of Earthquaker's pedals the other day, and have since purchased and fallen in love with this fuzz. Here's some info:
http://www.earthquakerdevices.com/de...ransmitter.htm
The bias control adjusts the voltage applied to the transistor, and dialed in right, I get a nice, super tight and precise sputtery fuzz. Turn the bias up and this thing can roar! It's amazing how pocket, yet present, this pedal seems to sit with my current setup. I've also been running an octave into it, and dialed right - this thing sounds like a nasty synth.
Pretty cool pedal...