Here the circuit diagram of Maestro Boomerang pedal / Wah-Wah pedal for electric guitar effect.
Note: Transistors Q1 and Q2 were designated P-2356.
The Maestro Boomerang is not only a wide range wah wah pedal but also a volume pedal. It’s deemed as one of the best wah pedals ever built – and I totally agree. The only other wah that comes close is my Electro-Harmonix Crying Tone.
The Boomerangs were manufactured by All Test Devices for the Maestro brand, which was a subsidiary of Gibson. The first model, the BG-1, was produced from 1969-1972 and later replaced by the BG-2, sometimes labeled as the Boomer 2, which stayed in production until 1976.
It can be hard to imagine how a pedal with such a simple circuit can vary so much. I mean, it’s basically a foot controlled tone control, but these definitely have a unique sound that continues to keep tone freaks everywhere seeking them out
Download the maestro boomerang pedal schematic diagram in PDF document from the following link: