OTHER TECH

For a 5.1-channel setup, front center and left and right surround speakers are added to the 2.1-channel setup. (Dipole surround speakers are shown here, but direct-radiating speakers can be used instead, as long as they're placed just behind, not next to, the listening position.)

Adding Surround Speakers

Home theater enthusiasts have a variety of surround system configurations to choose from. The most common is a 5.1-channel setup, comprised of left, center, and right front speakers, two surround-channel speakers located at the sides of the room, and a subwoofer. Many receivers also offer 6.1- or 7.1-channel capability, where one or two additional back surround speakers are employed for a more seamless sound field behind the listener. Some 7.2-channel receivers allow the use of two subwoofers, which can provide more even bass coverage over a larger area. The latest surround mode is Dolby Pro Logic IIz, which uses two height-channel speakers at the front of the room to deliver sound that comes from above, as well as around, the listeners. (More about that later.)

It's crucial that you set up the left, center, and right front speakers symmetrically. Whether you put the center speaker on top of or below the TV, it should be exactly between the left and right front speakers and aimed directly at the listening position. The center speaker should be slightly behind the left- and right-front speakers (assuming they're not wall-mounted) and no more than 2 feet above or below the left/right speakers' tweeters. (Some manufacturers recommend placing the three front speakers in an arc, with all three equidistant from the listening position.)

The surround speakers should be placed to either side of the listening position and slightly to the rear - not in the back of the room. They can be mounted on the wall or placed on stands, slightly above ear level. Surround speakers are supposed to create diffuse, ambient sound to heighten the sensation of an immersive sonic environment. To aid this, some surround speakers use a dipole or bipole design that radiates sound from both the front and back of the speaker's cabinet. Dipole or bipole speakers should be placed with their drivers facing forward and backward, with the null side of the enclosure pointed toward the listener. On the other hand, direct-radiating speakers (such as the satellites in a typical compact satellite/subwoofer system) should be mounted on the side walls, just behind and facing the listener.

In a 6.1- or 7.1-channel setup, the additional surround back speakers should be placed along the back wall at the same height as the left and right surround speakers.