Let me explain the electronics here, they were modified by Paul TBO (former owner, how are you?) and Edwin (from Bass Connection): 
 
The original was: volume, pan, filter, filter; Q and Q.  
1. added a master volume on the expected most front place  
2. took out the pan and changed by a volume; So we got bridge and neck PU volumes.  
3. Added a switch for circuit break with a red LED (red led replaced later by me with a 3-way toggle switch for the front and side led's fitted by Simsled UK) that indicated if the bass was on circuit break or not. It came from the time I mostly let the bass with the jack in. Those were done just up from the pace were the jack would be.  
4. the jack was replaced by a PU selector switch (who was not a Alembic standard, but now is orginal Alembic with pointer knob)  
5. The jack was brought to the side.  
Ciao! 
Stefano