This is a dirty octave down, powered by the classic Bazz Fuss on the input. I mucked around with that and Joe Davisson's "Shocktave" circuit. My goal was to get a similar sound to the Shocktave, but with better fuzz, fewer parts, and more options. I believe I have succeeded in that goal. I like the fuzz tones much better, and the octave down still tracks pretty good, especially with bass-heavy inputs. I imagine this thing would KILL on bass, but I don't have one to test.
There is a Mix control that blends the octave down in with the fuzz (same as on the Shocktave). I also added a switch that kills the octave down and adds a slight hint of octave up (check the clip below). With the mix at half way or less, chording still sounds pretty good. But with the mix higher, it's basically a monophonic type thing.
I do believe this is the most simple (yet still useful) octave down fuzz there is (so far). Probably not the most useful thing for a lot of people, but it works well in certain situations.
Here is a clip of it:http://soundcloud.com/effdub/downbox-fuzz-demo
First is clean, then straight fuzz, and then the octave down starts getting mixed in around 0:45 (ranging from a hint to 100% wet). Then I flip the kinda-octave-up switch at around 3:50.
I will be getting at least a small run of these made as proper PCBs. Details on that to follow early in January.
Here's the schematic: