Subwoofer series monitor audio radius power rating 220 watt system 1 way system principle active frequency response 40 120 hz amplifier type digital colour black housing surface paint housing material mdf enclosure control features adjustable transition frequency switchable phase control design front firing subwoofer speaker enclosure bass reflex number of subwoofers 1 bass chassis 250 mm subwoofer material woofer radiator woofer aluminiummagnesi