Treble booster build
- Using the PCB for the Banana Valve Booster.
- Using a NPN Germanium Transistor circuit
- For the Germanium transistor: an OC139/OC140. hFE should be around 80. Recommended is a 2N388A (but expensive!). The best (affordable) to buy online seem to be the CV7351 / MP38A (ebay), in bulk package, but you have the measure them yourselves.
- Using a TB83-ish circuit, as described in the 3-in-1 treble booster.
- For the Silicion transistor: a BC549C
- A bias circuit should be added (at least for the Germanium transistor), so difference in hFE can be corrected for optimal results.
To be decided:
- Because all treble boosters will include a volume switch, some a “booster/tone” switch and all will have a true-bipass, it is possible to have them all on or off, using a foot switch
- The foot switch of the Banana Valve Booster is a 3PDT switch, so not only is the input and output switched, but also the positive rail. This means that the pedal is effectively totally “off” (a bit strange -> Won’t you want the tube to glow al the time???). We might do the same thing for the other pedals.