Surround Sound at Home
Years of development by the movie industry, picture and sound, is now available to you and is quite
affordable. The best place to start learning what it all mean is from Dolby Labs.
The following section contains excerpts from "The Dolby Guide to Home Theater Sound"
Full paper is available at http://www.dolby.com/consumer/home_entertainment/roomlayout.html
Surround sound makes the difference
Surround sound, which is what turns conventional TV viewing into home theater, originates from program
material such as DVDs that have multichannel soundtracks. The multiple channels are reproduced by three
speakers across the front of the viewing area, and surround speakers to either side (Figure 1). The result is
sound that transports you into the world of you're watching; you feel less like a passive viewer and more like
an active participant.
A home theater system
features three speakers
across the front of the viewing
area plus surround speakers
to either side.
Dolby Digital: the sound of home theater today
The leading surround sound technology today is Dolby Digital. It is a method of compacting digital audio so that high-quality
multichannel soundtracks can be easily carried via digital discs and broadcasts.
Soundtracks encoded in Dolby Digital come to you via DVDs, digital television (DTV) broadcasts, and digital satellite and cable
transmissions. Dolby Digital decoding is licensed by Dolby Laboratories to manufacturers of home playback equipment.
Programs with Dolby Digital soundtracks and playback equipment with Dolby Digital decoding are usually identified with the logo.
What is "5.1" surround sound?
Dolby Digital brings 5.1-channel surround sound into your home. It provides five full-range audio channels: three for speakers at
the front and two for surround speakers at the sides. A sixth, low-frequency effects (LFE) channel carries those deep bass sound
effects you feel more than hear. Because it covers only about one-tenth of the audible range, the LFE channel is called a ".1"
channel. Its low bass sounds can be channeled to the subwoofer in the home theater system, if it has one, or to any other
speakers in the system that can reproduce low bass.
A newer variation of Dolby Digital, called Surround EX, encodes Dolby Digital program material with a third surround channel that
can be decoded at the listener's option for playback over additional surround speakers placed behind the viewers (Figure 2).
Surround EX program material is fully compatible with regular Dolby Digital 5.1 playback (the additional center rear information is
split between the left and right surround channels).
Welcome to the
Choosing your home theater sound system
This Guide assumes you are putting together a new home theater sound system from scratch. If you are converting an existing
analog Dolby Surround system to Dolby Digital, you will find helpful information in Frequently Asked Questions about Dolby
Digital in the Home, located under Home Theater at www.dolby.com.
While we can help you get the most out of your home theater system, Dolby Laboratories cannot make specific equipment
recommendations. However, you can rest assured that all products licensed to incorporate Dolby Digital decoding meet Dolby
Laboratories' high performance standards.
For specific product recommendations, consult the various publications that test home theater products, and/or home
entertainment equipment retailers.
Your home theater: it's as easy as 1, 2, 3
To play Dolby Digital programming, you need one or more program sources equipped with a Dolby Digital output, such as a DVD
player, digital television (DTV) receiver, digital satellite set-top box, and/or a digital cable set-top box. To play Dolby Surround
programming, all you need are regular analog stereo sources, such as a conventional TV receiver, VHS deck, satellite receiver,
or cable box.
To decode surround sound programming, you need an A/V receiver or other playback electronics that incorporates a 5.1-channel
Dolby Digital decoder for programming with Dolby Digital soundtracks, and a Dolby Surround Pro Logic or Pro Logic II decoder
for analog Dolby Surround soundtracks.
To hear Dolby Digital and Dolby Surround soundtracks, you need five speakers (six, if you use a subwoofer), and the same
number of amplifier channels in the playback electronics.
Put these basic elements together with your television set and you have a home theater, like the one shown in Figure 3.
Home theater speakers
Most speaker manufacturers offer complete home theater systems, usually based on a satellite/subwoofer configuration (see
Figure 4). These integrated systems make choosing and installing a home theater system much easier than it used to be, and
often provide higher performance for the dollar than a random assembly of individual component speakers
Satellite/subwoofer systems take advantage of the fact that the lowest bass frequencies are non-directional, which means the
ear cannot readily detect where bass sounds are coming from. As a result, these systems channel the low bass to a dedicated
bass speaker called a subwoofer. The subwoofer can usually be tucked out of the way, because its placement is not critical to
reproducing the directionality of the original sound.
Because they are not required to reproduce low bass, the satellite speakers can be compact, making them less intrusive and
easier to place. Many systems use identical satellites for the left, center, right, and surround channels. This means that all
speakers have the same timbre, or tonal characteristic, which is desirable in a home theater system. Other systems provide
identical satellites for left, center, and right, but the surround units may be somewhat different, usually with respect to their
radiating characteristic. Nevertheless, the surround speakers should still be timbre-matched to the front speakers.
Continue on Home Sound 2
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A "Must-Have" Book
Home Theater - Surround Sound
Super Home Theater