Down is active. The preamp will, however, continue to draw a small current from the batteries, so it is best to unplug the bass when it not being played for a period of time. Down is humbucking, up is single coil. Single coil pickups hum. When a humbucker is tapped, it hums unless it is blended with another pickup via the blend control.
Current drain is extremely low allowing unusually long battery life.
We have had reports of 6 months if the bass is not left plugged in when not being played. Inc. Exeptions are noted.