Subwoofer

A sub-woofer can be placed in any part of the room since low frequency sounds are non-directional.

They have built in amplifier and are independently powered.

You can supplement the left and right front speaker. Actually, its frequency range is even lower than full range front speaker.

Or you can let it take over the bass function.

There are lots of benefits to just the subwoofer assume this role.

Firstly, bass requires large movement of the cone called excursions. Large movements in turn generate heat and may damage the cone.

Secondly, the power amplifier is also overworked.

Thirdly, cone producing both bass and mid frequencies causes Doppler distortion and sound quality suffers.

Lastly, the combination of front speakers and subwoofer producing bass frequencies causes fluctuation in the bass response with high peak and dips in amplitude.

By separating the bass from the front speakers, the amplifier can have more power to generate the mid range and treble frequencies . The sound becomes cleaner. There is an improvement in the dynamic range and less distortion created. With a separate amplifier for the subwoofer, there is more power available for all the speakers.