Why does my single-coil-sized humbucker (Rails or Classic Stack Plus) pickup have a circuit board on the bottom? Does that mean it's an active pickup?

No. It’s correct that some of our single-coil-sized humbuckers (JB Jr., Little ’59, Li’l Screamin’ Demon, Duckbuckers, Hot Rails, Cool Rails, Vintage Rails and the new Classic Stack Plus) have circuit boards on the undersides of the pickup. However, the pickups named above are passive, not active. The circuit board material is used for internal wiring and hookup and does not indicate that the pickup utilizes an on-board pre-amp or electronic circuit. The fact that these pickups don’t require batteries is further evidence of their passive nature.

WRITTEN ON JUNE 15, 2015, BY sltwtr