MK-III Germanium Tonebender

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. The transistors in this pedal were hand sorted and thoughtfully selected for optimal performance. This build uses transistors in the middle of the recommend gain range for a MK-III for a traditionally bright and cutting fuzz that cleans up well.

Amplification Stage
GT308v - 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.
Volume - Controls the output volume of the effect

Tone - This is a standard dual filter that emphasizes the high-end when turned anti-clockwise and boosts the low end when turned clockwise.

Fuzz - This controls the signal level being sent to the third transistor. The more signal you send, the more Q3 will clip. This control is moderately subtle as the pedal has gobs of gain to begin with.

T1 (Internal Trimmer) - This 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 (Internal Trimmer) - This adjusts the bias for the saturation transistor, Q3, and alters the overall character of the fuzz. By default, this transistor is biased to -2v.

Notes

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.
Germanium transistors are temperature sensitive and may sound different depending on ambient conditions.
This pedal was designed to be used with a standard 2.1mm center negative 9v adapter and does not have provisions to use a battery.