OPP (engl)

OPPDeveloped and fine tuned over years, the OPP has developed into a small universal tool for every pedal board. Although the circuit is extremely simple, this is exactly what makes it so flexible and depending on the level of expansion everything is possible from a cable buffer, preamp, or booster to an overdrive.

Everything gets build on a practical pcb on which all shown circuits can be implemented quickly and safely.
Depending on the application, a few components are added or removed from the basic circuit.





TT-OPP as Buffer

Useful when long routing are present, for example from the guitar to the amplifier or from the FX loop of an amplifier to the FX board and back again or before a tone control and so on.
The buffer helps to avoid sound losses which often result of long cable routes (click for circuit diagram):

OPP Buffer

TT-OPP as Preamp or Booster with and without Overdrive

With a few more components, the buffer is transformed into a preamp to e.g. amplify weak signals to provide a higher signal level at the input of an amplifier to “thicken” the sound for a richer overdrive.

Additional overdrive can also be achieved by diode clipping, which transforms the preamp into an overdrive.

Here is the circuit as simple preamp / booster (click for circuit diagram):


OPP Preamp

and here is the circuit with added diode clipping:

OPP OverdriveLayout

OPP Layout

(click for schematic)


The kit for this project and other accessories can be found in the Shop.

Pictures of the build