The StudioLive™ 18sAI active 18-inch PA subwoofer is designed to combine with the full-range StudioLive AI-series speakers to form a true four-way system, while still being flexible enough to work with other powered loudspeakers. Driven by 1,000W of Class D amplification and massive amounts of onboard DSP, it features three alignment presets that compensate for placing the subwoofer a meter or two away from the full-range system allowing it to correctly combine with full-range cabinets. This results in tighter bass response and bigger sound without more volume. Onboard DSP contours retune your subwoofer based on your application: normal live sound or extended low frequency. The 18sAI also provides stereo full-range line inputs (XLR/¼-inch combo) and full-range, switchable stereo/summed-mono line outputs (XLR). Free SL Room Control speaker-management software provides wireless setup and advanced control of individual and grouped speakers, including alignment delays, polarity reverse, and real-time performance monitoring—the equivalent of a high-end outboard speaker processor and more.