Surround Sound in a Nutshell

After a high definition big-screen television, surround sound is the next most important feature of a home theater system. 5.1-channel surround sound systems are typically composed of three front left/right/center speakers, two surround speakers on the side walls, and a subwoofer. 6.1 and 7.1-channel systems can add some extra speakers against the back wall of larger rooms. According to new surround sound standards, a 5.1.4-channel system, for example, would have five floor speakers, one subwoofer, and four height speakers.

The Traditional Setup

In 5.1 speaker systems, each speaker is responsible for a specific part of the movie experience. Dialog is handled by the front center speaker, while ambience and effects are provided by the other front and surround speakers, and bass is handled by the subwoofer. Depending on your preferences, you can feed these speakers with either a surround receiver or a two-box system of a surround preamplifier and a multichannel power amplifier. There are soundbars and soundbases available for more informal installations, such as bedroom sets, but they provide only a limited amount of surround sound (or just stereo).

Dolby Audio Experience

Although DTS is gaining ground in streaming, you are more likely to see Dolby Digital and its improved version, Dolby Digital Plus. Dolby Audio is the marketing name for technologies such as these. Dolby Atmos, the next generation of surround technology, builds on the foundation of Dolby TrueHD and Dolby Digital Plus, but with an expanded speaker lineup that includes height speakers. 

THX Certified-Technology

Originally, THX did not exist as a surround format, but as a certification program for movie theaters, as well as receivers, displays, cables, and software that go into a home theater system. Imagine it as an alternative to Dolby Surround and DTS Surround. Furthermore, THX offers THX Loudness Plus, which is a useful listening mode. A variety of technologies are licensed by Audyssey, including auto setup, room correction, low-volume listening modes, height/width listening modes and bass-related listening modes. Some manufacturers of surround receivers offer their own versions of auto setup and room correction technology to avoid the expense of Audyssey.

Speaker Placement

The best approach when deciding where to position your speakers is to follow what the instruction manual says. This may sound oversimplified, but the fact is, different speakers are designed to be used in different ways. One possible way to manipulate the sound without compromising the entire setup is to adjust the front center speaker. You can try angling it down toward the listening position by placing something underneath the back of the speaker enclosure, for starters.

The information in this blog post was adopted from the 20th Anniversary Edition of the book, Practical Home Theater: A Guide to Video and Audio Systems (2022 Edition) by Mark Fleischmann.