The BTS System is a complete control system for EMG bass pickups. It includes an Active Balance Control that allows for loss-free balance between two pickups and has a center detent for the middle position. If you are using EMG-HZ Passive pickups, or other passive pickups you will want to use the B125 Active Balance Control which features buffered inputs for a higher input impedance. The additional BTS Control is a 2-band equalizer that features single-pole filters for broadband equalization. The BTS Control has a high input impedance and can be used with active or passive pickups.