The Kelton subwoofer uses a dual chamber structure, with a drive unit in the rear chamber and a 25cm Passive Radiator in the front chamber. The drive unit vibrates the front chamber, which causes the large Passive Radiator to vibrate and produce bass sounds. With this structure the front chamber serves as an acoustic fi lter, so you get a crisp sound with minimal noise. The thinness and high compliance of the passive radiator also help achieve an exceptionally clean, robust and responsive bass performance.