I have a custom mahogany fretless. It has a single J-pickup in the bridge position. It is a Bartolini. The sound is rather thin. I don't have the option of getting more bottom by adding a neck pickup as there is a hollowed-out sound chamber between the bridge pick-up and the neck. I'm looking to replace the Bartolini with a single j-pickup with much more bottom end. Also, since it is a single pickup, I'm looking for a humbucker (something split or stacked ). Any recos for single J pickup, hum-cancelling, with a deep bottom end to make up for the lack of a neck pick-up?