Surround speakers should use medium and high frequency speakers. On the sound system, there is basically no bass in the surround channel, and the bass direction is very poor, which is taken care of by the front main speaker and subwoofer. Good surround effect can only be achieved by using medium and high frequency speakers. Therefore, the surround box is relatively small, and no large-caliber bass unit is installed. The power of surround speakers is also smaller than that of front speakers.