The SF-1521A is a unique, powered hybrid subwoofer system which is part of the SF-Monitor system. It combines the hard-hitting and defined performance of a 15? loudspeaker with the deep, air-moving power of a 21?. The SF-1521A employs the 15GNR loudspeaker for mid-bass reproduction up to 200 Hz. The extreme low end of the system´s frequency range is handled by a single 21UXN4 loudspeaker ideal for demanding dance club applications. A Class D two channel amplifier developing 1700 Wcontinuous per channel provides the power. The SF-1521A can also be deployed for impressive low frequency reproduction in support systems.