A magnetic sound hole pickup can be added to many Fishman onboard preamp systems. The sound hole pickup’s signal wire will be wired to the “Ring” terminal of the output jack and the ground will be connected to the sleeve. If the soundhole pickup is active, like our Rare Earth pickups, you would remove the batteries from the sound hole pickup and install a jumper between the positive and negative battery terminals on the pickup. The battery wire of the pickup would then be connected to the “Switch” lug of the jack, so the onboard preamp and active sound hole pickup will run off the same 9 volt battery.