X3 : active blend preamp with 3 band EQ active only independent input stage for each pickup buffered signals are mixed in the active path smooth blend control, no insertion loss at center 0..+10dB independent gain control (also externally switchable) can even match active pickup with passive, P with J, etc.. as well as identical pairs independently selectable input impedance/pickup load selectable EQ frequencies:    bass: +/- 12 dB @ 40/80 Hz    mid: +/- 12 dB @ 220/400/600/900/1800 Hz    treble: +/- 14 dB @ 4/5/10/20 KHz power: 9V, 1.3 mA dimensions: 45 x 30 x 15mm (1.77" x 1.18" x 0.59") without wires wiring (click for hungarian .pdf):  Battery fuel gauge your phone has it. your car has it. now your bass has it too. optimized for 9V, max input voltage is 30V blinks after you plug in, then goes to low power mode until you unplug the cable sleep current is less than 3 uA zero power consumption while the cord is disconnected    3 pulses: battery voltage is above 7.5 V    2 pulses: U > 6.5 V    1 pulse: U > 5.5 V    S.O.S. signal: U < 5.5 V, replace battery bright green LED, visible under direct sunlight PCB dimensions: 25.4 x 9 mm (1" x 0.36"), LED diameter: 3mm optional 3mm diffuse light guide available (installation example pictured below) low-res video: