This is the integral speaker that produces the theater experience in home-theater sound. The Subwoofer: a Vital Part of Your System. DVDs and digital music sources hold a huge amount of audio data, including a considerable amount in the low frequency range. Multi-channel sound formats dedicate an entire channel to the low frequencies (the .1 in 5.1-channel sound), used to deliver the bass in music and explosions, thunder and other low frequency sound effects in movies. Ordinary speakers are not large and robust enough to handle these frequencies, especially for long periods. This is where the subwoofer comes in. By outputting bass sounds with high power and low distortion, it ensures that you are not missing anything, and it also makes the overall sound richer and properly balanced.
Capable of handling 100W of dynamic power, this subwoofer ensures that you hear all bass sounds, even the loudest short bursts, with fast attack and total clarity. The effectiveness of Advanced YST (Yamaha Active Servo Technology) is based upon two principles: the Helmholtz Resonator and negative-impedance drive. Active Servo Processing speakers reproduce the bass frequencies through an air woofer, which is a port or opening in the speaker cabinet. 28-200Hz low frequency response Black

Advanced YST II (Yamaha Active Servo Technology II)
Front-firing active subwoofer
Linear Port for minimizing extraneous noise
20cm (8"") cone driver with magnetic shielding
High 100 Watts dynamic power