5.1 Channel Surround
This setup includes three center channel speakers in front and two surround speakers in the back. Additionally, a subwoofer is placed somewhere in the same room (for low frequency effects).
7.1 Channel Surround
This setup is configured with 3 speakers in the front, one on each side and two in the rear, for the fullest surround effect. Make sure to place them behind your seating area at an angle of 135° to 150° from the center.
9.1 Channel Surround
The 9.1 surround sound setup delivers a cinematic experience through nine speakers and a subwoofer. Adding to the 7.1 setup, the 9.1 setup makes use of two front height channels. These front height speakers add a vertical dimension to surround sound listening. Height also provides music and audio effects another axis, thus creating a more immersive experience.
What About Dolby Atmos? To experience Dolby Atmos, you must add either two or four in-ceiling speakers or elevation speakers to your existing surround sound setup (e.g., 5.1.2 or 7.2.4).
Subwoofer: is a loudspeaker responsive only to the lowest acoustic frequencies. In the words of Meghan Trainor, a subwoofer is all about that bass! And you cannot produce surround sound without it!
Center Channel Speakers: the most important speakers in that most of the action, and conversation, happens front and center on your screen, meaning that the center channel is the one reproducing it.
Surround Speakers: provide ambient noises, which adds a third dimension to your movie-watching experience.