It's been a bit of a rough time of late and when things get a little ..... uneasy, I tend to try some creative things to take my mind off it. Sometimes I work on guitar building, or new pickup ideas, or amps, and sometimes I make pedals that have been bouncing around in my head.
The Spitting Cobra Fuzz is one of those.
My love of the classic Japanese Companion/Shen-Ei FY-2 from the late 60's is well known around these parts. Over the years I've made a few fuzzes based on this great little circuit, mostly as my Fuzzilla range.
One of the real drawbacks of this early Japanese fuzz circuit is the fact that it drops in volume when engaged. It's a GREAT fuzz but doesn't reach unity when switched on which can be frustrating for some. I have made a Fuzzilla with a gain stage after the fuzz to take it well over unity (this has since become common) and I currently make my Fuzz Box FY-2 which is this circuit in standard version with the added option of switching in a discrete boost stage after the fuzz to take it over unity gain without messing with the original tone too much.
While messing around with this circuit to build these I made a version with the passive filter section at the end of this circuit, which is what drains so much volume out of the original, removed and played around with some values in the fuzz itself.
With the passive tone stack section gone it really comes alive but loses some of that great original compressed fuzziness that I love so much.
So I started messing with some other tone stacks to see what could be done to reinvigorate this little simple 2 transistor circuit.
I ended up putting an active Big Muff style low pass/high pass filter section in where the passive section was in the original circuit and it behaved very nicely with that original filter gone. A little bit of messing around with values in the BM style filter and BAM, there is was.
I'd also been playing around with dropping out of the circuit after the first gain stage to see what it was like as a single transistor boost. The "FUZZ" control on the original feeds the first transistor stage into the second and "mixes" them together before that pesky filter stage. The drive from the first stage was .... OK but after a bit of messing around I found a nice compromise of drive with a little bit of background fuzz and the full on original fuzz that I turned into a BODY toggle switch. With your guitar volume rolled off the "thin" side can be used as a boost to overdrive tone with very little fuzz. As you roll the guitar volume back in it fuzzes back up but stays quite articulate. The "thick" side is all FY-2.
The volume control comes in quickly and adds volume and bass in both toggle settings. Of course the added attraction of the active filter not only allows you to sculpt the tone how you want it but also makes the circuit well above unity once kicked in. Win-win.