MKIII - Germanium Tone Bender

MKIII - Germanium Tone Bender

903 MKIII - Known for being the brawny brother of the bunch, the 903 MKIII is a faithful reproduction of the coveted 1968 pedal of the same name. The signal path of the MKIII has been built to the exact specifications of the original, but with the addition of a voltage inverter. This allows the effect to be used with a standard center-negative jack while maintaining the positive-ground operation of the original.

The Transistors - This MKIII was built using Ukranian sourced components.

Amplification Stage:
GT308v or P416b - These Germanium transistors are known for having a warm germanium tone but with excellent clarity.

Saturation Stage:
GT402B - Warm and Fuzzy, These Germanium transistors are known for being politely aggressive and sound great as the final transistor in a number of fuzz circuits.

External Controls:
Volume - Controls the output volume of the effect
Tone - This is a standard filter. Turn right to boost bass, left to boost treble.
Fuzz - This controls the gain by adjusting the signal being sent into the third transistor.

Internal Controls:
T1 - This trimmer sets the voltage bias for the Q1/Q2 Darlington pair and alters the overall character of the fuzz. By default, these transistors are biased to -3.5v.

T2 - This trimmer adjusts the bias for the saturation transistor, Q3, and alters the overall character of the fuzz. By default, this transistor is biased to -2v.


• This pedal is responsive to the input volume and will clean up as the input volume is rolled down.
• Like many vintage circuits, this pedal sounds best when used first in your signal chain.
• Adjusting T1 and T2 is not recommended unless you have a digital multimeter and prior biasing experience.

Due to these pedals being hand built, this product may have minor variations between builds. Enclosures may have minor blemishes from handling during assembly, testing, or shipping. We do our best to handle and ship them all safely so please forgive any small cosmetic defects. They are built by hand after all, not by factory robots