I have a Bartolini NTMB 918 Preamp that I pulled out of an older bass I built. It was wired for a 3 knob setup with a mini active passive switch. Pots were configured Vol/Vol - Bass/Treb - Mid w/ push pull mid selector. Needs to be wired up but schematics on Bartolini's website are easy to follow. No knobs included. 110$ shipped OBO