Satronik Fuzz Sustainer

A few months ago, Alex and I made an attempt to trace an old polish fuzz/distortion that looked incredibly cool and was supposed to sound in the vein of a Rat or a Big Muff. Soon, we realized that the circuit design was quite unique, not resembling anything else. It is basically a bootstrapped booster into a 741 op amp running way above full tilt for op amp clipping. An offset null trimpot is there to fine tune the gating and the sustain for the op amp. Then the signal goes into a BJT powered Baxandall tone section with the bass control fixed midway. The tone control is the Treble control in the Baxandall network. 

So far so good but we failed just before the finish line...four of the resistor values was impossible to figure out so we pot it to bed. A few months later Blue Colander Stompboxes entered the scene.. They traced two Satronik units and posted a schematic on their DIY section of their website. That helped us fill in the missing gaps!

Note that several cap and resistor values varied through its lifespan as well as the transistor selection. The differences are quite minor so the sonic character shouldn't that far off from unit to unit. The values in the layout below are almost solely from AlexS and mine trace.

 

Schematic