The Sadowsky 4 knob Onboard Bass Preamp is a completely prewired system offering the same controls and preamp as all Sadowsky Basses.
Volume-Pan-VTC-Treble/Bass
VTC=Vintage Tone Control (pull up for total bypass).
 
The preamp can be installed with the included control plate or mounted through a rear control cavity in either a 4 in line or diamond pattern. Pickups attach via solderless connectors at the pan pot. Direction of the pan pot can be easily reversed by which pickup terminals are used.  Installation requires a side jack and a battery compartment. 
 
This system is not compatible with EMG or any other active pickups requiring anything other than a 250K or 500K volume pot.  For these applications, please custom order a parts only preamp kit and use your original volume pot.