P1 should be wired with neck pickup positive; P2 should be wired with bridge pickup positive; GND should be wired with two pickups negative High quality bass preamp, not inferior bass Circuit cheap factories Please your local luthiers if you 't know how to install the Circuit Specifications: Condition: and High Quality Volume B50K Pickup MN250K Bass: +/- 14dB 80Hz B100K Middle: +/- 8dB 900Hz B100K Treble: +/- 23dB 3-7KHz B100K Material: Metal + Plastic colour: Random Color Note: Random color, 't accept the specified color. Package Contents: 1 x Bass Preamp Circuit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.