The Yamaha YST-SW80 is a classic active servo-powered subwoofer designed for home theater and stereo audio setups. Utilizing Yamaha's proprietary Active Servo Technology, it combines a negative-impedance amplifier with a Helmholtz Resonator to generate powerful, deep bass from a relatively compact cabinet enclosure. Key Specifications & FeaturesAmplification: Integrated 70W to 85W RMS amplifier (depending on regional variant).Driver Size: 8-inch (7.87") cone woofer.Frequency Response: Overall range spans 23 Hz to 170 Hz.Front Panel Controls: Easy access to physical knobs for Master Volume, High-Cut crossover filter adjustment (50 Hz to 150 Hz), and a Power button.Phase Control: Includes a normal/reverse phase switch on the unit to seamlessly align the subwoofer's timing with your main stereo speakers.Auto Power: Automatically powers on when it detects an incoming audio signal and returns to standby mode shortly after the music stops.