Guitar Shop 101: The ABCs of Output Jacks | Premier Guitar Mar 25, 2016The latter acts as a power switch for active pickup systems by connecting and disconnecting the third lug when a standard 1/4" plug is inserted or removed from the stereo jack. For example, when the black (negative) wire of a battery snap is soldered to the third lug, inserting a 1/4" plug into the jack engages the battery by connecting the negative battery wire to ground and Author: John Levan active pickups wiring | eBay Find great deals on eBay for active pickups wiring. Shop with confidence. Skip to main content. eBay Logo: EMG J5X SET BLACK 5 STRING JAZZ BASS ACTIVE J PICKUPS POTS, JACK & WIRING See more like this. EMG J5 SET BLACK 5 STRING ACTIVE JAZZ BASS PICKUP SET POTS & WIRING ( TUNER ) Brand New.