BJT to Diode Frequencer Doubler

A bipolar transistor splitter that drives two diodes for full wave rectification/frequency doubler effect.

Earliest example appears to be the Fender Blender (1968 or 1969), which was likely trying to emulate the effect created by Roger Mayer's transformer driven Octavia. Dropping the transformer eliminates an expensive and fragile part.

Examples:

Fender Blender

Foxx Tone Machine

CBS/Arbiter Doubler

Dan Armstrong/Mutron Green Ringer

Roger Mayer Rocket Octavia (1980 onwards)