The loudspeakers in a typical media-room system include:
- A center channel loudspeaker, which is the most important loudspeaker. Virtually all of the dialogue is sent to the center channel. Don't skimp here; a low-quality speaker will make it difficult to understand the actors in your favorite movie. The center channel speaker should be placed as close as possible to the television. It is usually mounted directly above or below the screen.
- A left front and right front loudspeaker, which should be identical and placed an equal distance to the left and right of the television.
- At least two rear surround sound speakers to give the sound a three-dimensional effect. They should be placed above and slightly behind the main seating area. How much sound comes from these speakers depends on what the sound engineer producing the program wants. In many movies that are mostly dialogue, the rear speakers might never be used, while in an action adventure movie, they could be utilized during the majority of the film. Sound coming from the back can be as dramatic as an airplane flying overhead, or a car approaching from the rear in a chase scene, or as subtle as background noise in a restaurant.
- A subwoofer can be placed almost anywhere in the room. Humans can't identify the direction from which a bass sound comes --a phenomenon that makes it very convenient for placing the subwoofer in home theaters and media rooms. Usually the largest of all of the loudspeakers in a surround-sound system, the subwoofer can be placed where it is partially or totally concealed. In some loudspeaker systems, the woofers for the bass are in the main left and right loudspeakers.
- For more on speaker placement, check out the section on room layout at the Dolby website.
Some of the most common questions I get are about Dolby Digital and DTS surround systems, often defined by numbers such as 5.1. With such systems, the number 5 specifies the number of main speakers that can be used; the 1 indicates that a subwoofer can be connected. Later versions of surround-sound processing allow for six or seven main loudspeakers; they are labeled 6.1, 7.1, etc.
Dolby Digital and DTS (digital theater system) are the main surround-sound processing systems. Most audio video receivers are capable of decoding either one.