Harnessing the energy required to accurately generate extremely low bass from a subwoofer is no small feat. So Yamaha developed Active Servo Technology to help. By precisely governing the motion of our low-frequency drivers, this approach ensures tight, responsive performance. While also helping generate maximum output from a relatively small speaker enclosure. Incredible bass from a small cabinet. Easy and convenient placement because of smaller size. Better imaging - imagine sitting in the front row of an orchestral performance - close your eyes and try to visualize the placement of the members of the orchestra.