SD-1 Mod by Robert Keely

***** SD-1 5-Star Ge Mod ****
Keeley Custom Shop designed this mod to enhance the tone and functionality of the SD-1.

Freely copy and distribute. We have the right to change our modifications at any time without notification. It is fun to watch what big name people use the mods.

Board Number New part Old part Reason Where to get the part

C10 –> Metal Stack Film 1uF, remove electrolytic, increased fidelity, digikey

C7–> Metal Stack Film 1uF, remove electrolytic, increased fidelity, digikey

R6 –> 2.4k ohm metal film, 4.7k, increased distortion, digikey

C3–> 0.1uf metal stack film, 0.047uf, fidelity and bass response, digikey

C2–> 0.1uf metal stack film, 0.018 fidelity and bass response, digikey

R2–> 620k ohm metal film, 470k ohm, increased input impedance, better bypass, digikey

Add 47pF cap across diodes in clipping section to smooth out distortion, just like TS9, radio shack

On some older units, short out D3 and the 470 ohm resistor in the power supply section to increase the voltage to the circuit. This increase the headroom and gain. Newer units have it shorted already.

Here is the tricky part of our mod, take a germanium (Ge) transistor and use the Base-Emitter junction (legs) of the device and use it in place of D6. If you use a PNP transistor, the Base will be the negative or cathode side, the Emitter will be the anode. Here is a diode drawing Cathode—|<—-Anode. This increases the amount of distortion produced by the pedal, it also sound really nice. Try this! Don’t leave it out! It’s fun. Get your Ge transistors from Steve Daniels

If you want to drill out the LED and install a 5mm big job, change R30 to a 1.2k-3.3k ohm depending on brightness and battery drain you want, replacing the stock 3.9k ohm.

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