Maestro Invader Distortion gut shots. What's it based on?

[Aentons]

Ive been curious about this one and happened across one at a good price so I figured I'd play it for a few minutes and then take it apart. Anybody have any educated guesses what circuit it may be based around?















And for fun... To show how they did the triangles

[Aentons]

VR1 Gain = 500kA
VR2 Tone = 25kB
VR3 Level = 100kB