Purple Mystery Box (Distortion) Overdue

Versatile distortion pedal with parametric EQ, amp simulation and stuff.

Knobs (left to right): Level, Low, Mid Freq, Mid, High, Distortion.

Switches (left to right): Amp Sim, Modern/Normal/Classic, Hi Cut, Normal/Bright/Warm

Powered by 9V battery or 9V DC centre-negative power supply.

Circuit: Biyang Metal End (?). Donated by Simon Field.

What is Distortion?