Presonus AIR18s Active Sound-Reinforcement SubwooferIntroducing the Presonus AIR18s Active Sound Reinforcement Subwoofer Designed to complement any full range PA loudspeaker, and a perfect companion for the PreSonus AIR series, the AIR18s active subwoofer delivers a powerful, clear and accurate low end punch. With its 18 inch low frequency transducer, driven by 1,200 watts (peak) of Class D power, it provides plenty of detailed bottom end, all the way down to 30 Hz. Brilliant on the move and in situ