You don’t have the space for a big subwoofer enclosure ALPINE underseat subwoofer, but still want the thrill of sub-bass? At only 3″ deep, Alpine’s PWE-S8 powered subwoofer fits in all kinds of tight spaces: in the trunk of your car, behind the seat in your pickup, or even under the seat in some cars. And it’s made to stand up to life on the road, with its rugged cast metal enclosure that’s built to take the hard knocks of a tight installation while protecting your equipment.