This is an open-source bass pre-amp meant for internal use in active basses with humbucker inputs. The circuit is a tribute to the classic 2-band pre-amp used in the original MusicMan Stingray, with a few modifications.

Board layout and schematic files are in EAGLE format, while the simulations are done in LT-SPICE.

The pre-amp has a buffered input to maintain very low thermal noise, it uses a rail-splitter IC instead of a resistor divider to ensure clean tone with very low power, and the voicing is modified to be less treble-heavy to ensure low EM interference.

PDF Schematic

OSH Park Link

Here's some simulations and tests of the voicing at various pot positions:











Copyright 2014, Russell McClellan, all rights reserved.

Basspre MM-2 by Russell McClellan is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.