The Fuzzolo is one of the newer Zvex designs in a 1590a box. It’s a stripped down Woolly Mammoth with a SHO added to the end, so it’s got a huge fuzz sound. In production versions, there’s a moveable jumper internally to go between active and passive pickups. You could use a SPDT switch to accomplish this, and make it easier to switch between the 2 modes, or you could eliminate the 2 input resistors (750Ω and 39k) and use a 50k pot as a pre-gain control. The PW (pulse width) pot pans between a square wave and a wide/narrow pulse width. Like the original, this should fit nicely in a 1590a enclosure.
