Audio Visual Design Group

Surround Sound Systems

A surround system adds much more than loud music and movies to your home theater. Immersing the viewer in the movie-watching experience, this audio system is called “multi-channel” because individual speakers deliver specific channels of sound. The effect comes from front and center, the special effects come from the rear and the bass tones are delivered through the subwoofer: The result: You’re in the middle of the action, and the reality of the movie is heightened.
A surround system includes at least five speakers (up to seven), and optional subwoofer or two and a receiver. All components have to be wired through the receiver, and the speakers should be installed in the best positions for the room in which you will be watching movies.

The Receiver
A receiver integrates a processor, amplifier and tuner into one chassis. Pick a receiver that has Dolby Digital and DTS, about 85 to 100 watts per channel. Prices can vary. If you wish to take it one step farther, you may purchase separate processors, amplifiers and tuners. This gets more pricey, but you may choose the exact specifications you wish and have the components only doing one function, the function they were designed for.

Sound Formats
Dolby Surround creates four channels of information: front left, “phantom” center (created by left and right), front right and rear surround. There is a greater separation in channels if you move up to Dolby Pro-Logic, which also incorporates a dedicated center channel but still has the same signal in both rear speakers. Dolby Digital (also called Dolby 5.1) adds stereo rear surrounds as well as a dedicated subwoofer channel (the .1 in 5.1). Recently Dolby introduced 6.1 & 7.1 surround. In this setup, Dolby incorporates an additional two "back" speakers to totally engulf the listeners in the movie watching experience. Individuals may also choose to do a 5.2,6.2 or 7.2 surround system, which is simply incorporating a second subwoofer. You must have a Dolby Digital receiver (or amplifier) to accurately decode the signal, because Dolby Digital uses its own encoding process.

The Speakers
In a Dolby Digital surround-sound system, you have two front speakers (left and right), a center channel, two rear surround speakers (left and right).

The center channel produces approximately 80 percent of all the sound heard in an average movie, carrying much of the dialog as well as music and some effects. Place this speaker either directly on top of or directly below your television. The left and right front speakers should match the center channel and mounted an equal distance from the center channel, pointed toward the listening area.

Surround speakers ideally should be placed above and only slightly behind the listening position. A subwoofer is optional but highly recommended for a true movie experience. Almost all Dolby Digital and DTS soundtracks now have a “.1 LFE” (low-frequency effects) track designed specifically for a subwoofer. Subwoofers are typically cube-shaped, with large single woofer pointing either directly at the ground or directly at the listener. Standard subwoofers are usually placed in a corner of the room. “Powered” subwoofers are subwoofers with their own onboard power amps. Movies have more low-bass information than music, so subs are particularly effective in a home theater.