The sub's real innovation, however, derives from the Advanced Yamaha Active Servo Technology II system, which optimizes the speaker impedance to create more stable, energetic and accurate low-range tones. The system also drives the speaker cone with tighter control than other subs, resulting in a more natural-sounding, explosive performance. The QD-Bass (Quatre Dispersion Bass) technology ups the ante by using its down-firing drivers and square, pyramid-shaped reflective plates to radiate the sound efficiently in four horizontal directions. This negates any effects caused by the floor surface while reducing unwanted resonance and distortion. The extraordinary power produced by the QD-Bass system also lets you place the YST-SW325 virtually anywhere in the room without suffering a dropoff in performance.

Adding to the sub's versatility is a Bass Action Selector System (BASS) that automatically switches between movie and music modes to ensure an optimum frequency response for each. Other features include a luxurious black wood finish cabinet, a 50 to 150 Hz high-cut filter (continuously variable), an auto standby mode with a sensitivity selector (high, low, and off), and magnetic shielding against video interference. The subwoofer measures 12.38 by 14.94 by 14.75 inches (W x H x D) and is backed by a two-year warranty on parts and labor.

What's in the Box
YST-SW325 subwoofer, nonskid pads, user's manual.