This DT Powerfield active subwoofer uses an 8" driver with a huge excursion to reproduce 32 hz bass with minimal distorion. Built-in amplifer rated at 350 watts (if you can believe it! ). Powered either from high level speaker terminals or from subwoofer output on a receiver or amplifier. Rear panel controls include level (volume) and low-cross frequency point. For a demonstration send an email or phone 801 487-3047