The new YST-FSW150 is a down-firing subwoofer designed to bring premium bass and realistic effects to your surround sound home theater system. Advanced audio technologies like YST bring you unparalleled performance in a compact and attractive chassis. YST stands for Yamaha Active Servo Technology – it’s a unique system in which the speaker and amplifier work together to cancel impedance, producing a perfect linear speaker motion. This assures you the highest levels of sound pressure and overall performance. This is a powerful 130-watt subwoofer system designed for the demanding home theater enthusiast. For incredible sound and the best matching for front surround systems and micro component systems, choose the Yamaha YST-FSW150 Down-Firing Active Subwoofer.