YAMAHA YST-SW225BL Powered Subwoofer Black *Free Shipping *(YSTSW225) 8 Inch Bass Driver / 120 Watt Built-in Amplifier / Great for Stereo and Home Theater / Shielded / Variable Frequency Crossover Control Yamaha's Patented Advanced Active Servo Technology (Advanced YST II) generates incredible Bass from small speaker enclosures. Its advanced negative impedance converters intelligently adjust the negative impedance generation as the speaker moves, creating a hard, rigid cone that prevents deep resonant waves from leaking out of the speaker cone. This means the full power of the waves is forced out through the air port, resulting in clear, powerful bass. The user-adjustable continuously variable high-cut filter sets the highest frequency the Subwoofer will deliver. It can be set anywhere from 50 to 150 Hz. For instance, if the filter is set at 75 Hz, only frequencies 75 Hz or below will be delivered by the subwoofer. This allows the sub's Output to be matched to the other speakers in the system and the room's acoustics for a seamless presentation. 8" Multi-Range ; 20cm Cone Rigid MDF Cabinet Contruction with Black Noir Finish Magnetically Shielded 120 Watt built-in amplifier Advanced YST II Active Servo Technology Auto Standby Power On/Off with Override Switch Line Level and Speaker Level Connections