russellmcc / basspre-mm2

MusicMan-inspired 2 band bass pre-amp

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Basspre MM2

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:

Flat

Simulation

flat

Bass Cut

Simulation

![bass cut](graphs/bass cut.png)

Bass Boost

Simulation

![bass boost](graphs/bass boost.png)

Test

![bass boost](tests/bass boost plot.png)

Treble Cut

Simulation

![treble cut](graphs/treble cut.png)

Treble Boost

Simulation

![treble boost](graphs/treble boost.png)

Test

![treble boost](tests/treb boost plot.png)

Both Boost

Simulation

![both boost](graphs/both boost.png)

Test

![both boost](tests/both boost plot.png)

Both Cut

Simulation

![both cut](graphs/both cut.png)

Test

![both cut](tests/both cut plot.png)

Copyright 2014, Russell McClellan, all rights reserved.

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

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MusicMan-inspired 2 band bass pre-amp


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