Got a request for the BB Preamp, but not the current version. The earlier version uses a dual-gang pot for the Level control and apparently more bass response. Like many of Xotic’s offerings the BB owes a lot to the classic Tube Screamer. Schematic can be found here.
If you’d prefer to build the newer version without the dual-gang Level pot, you can use the same board. Just remove the 1µ capacitor and the 1k and 47k resistors in the bottom right side of the board and replace with a jumper like this:
