nice addition to my gift pedals collection. Original stompwitch was dead so replaced it by a DPDT, so now it’s true bypassed. Works like a charm. Everybody knows it’s just an other big muff pi rip-off but in a tonebender-style diecast alloy casing.
But wait, once you plugged it you’ll rapidly noticed there is something more than a big muff in it. Some gate circuit is there to tame things a little bit. It’s controlled by the sustain pot and you can enhance its effect even more by reducing the volume output of your guitar. This way you can get some kind of broken violin effect.
i had to remove the slider pots from the pcb to access the copper side and be able to trace the circuit: Jumbo Fuzz schematic v2 (now with correct symbol for Q4: AC127 germanium NPN (blue dot).
listen to the beginning of the clip where i try to get that crappy violin sound (tone to zero), then sliding the tone pot to the max, then after 1 minute putting sustain to max and playing into some extra delay .