Dolby Digital is a surround sound format offering as many as six distinct sound channels that can place a sound effect anywhere. The name 5.1 means the system is made up of five full-range channels (front left and right, center, and right and left surrounds) and a channel that just carries bass for use with a subwoofer (the .1 in 5.1). This .1 channel is called the Low Frequency Effects (LFE) channel and adds a sense of realism and depth that makes everything from explosions to music more exciting.

 

Dolby Digital is an all-digital format, which means it can only be found on digital formats like DVD and digital TV broadcasts. But most Dolby Digital receivers and decoders also include Dolby Pro Logic II decoding, so you can still enjoy your VCR tapes and TV shows in surround sound.

 

Dolby Pro Logic II
Five speakers create a surround sound environment, and this system can create a very convincing surround effect from just about any two-channel source.

 

All Pro Logic II systems have two settings: one for music and one for movies. Put in your favorite CD and you’ll be amazed at how natural the surround effect is. The voices are where they should be and yet the music envelops you completely. The Movie mode is designed to let you get results very much like a digital 5.1 system from analog sources like videotapes and TV broadcasts.

 

Better known as DTS, this system premiered in movie theaters in 1993 with the movie "Jurassic Park". It is also a type of digital surround sound format with six separate channels of sound. The difference between DTS and Dolby Digital is the level of compression.

 

DTS insists that its lower levels of compression make a noticeable difference in the sound quality. Whether you agree or not, you don’t have to choose between the two formats because almost all surround sound receivers decode both DTS and Dolby Digital soundtracks.

Both of these offer 6.1-channel surround sound. In addition to the right and left front, center, and right and left surround channels, these include a center rear channel to help fill in the space between the two surround channels.

 

You don’t need a new DVD player to take advantage of these new 6.1-channel systems. With a 6.1 receiver, your existing DVD player will do just fine.

 

All surround sound systems, regardless of the technology or number of speakers used, are trying to accomplish the same thing: make you feel more involved in the action. And just about all of them have more things in common than not.

 

Most require five speakers. Some older systems like Dolby Surround use fewer speakers, and some newer systems like Dolby Digital Surround EX and DTS-ES use more, but most still use five: right and left front, center, right and left surround.

 

All surround sound formats benefit from a subwoofer. Newer systems like Dolby Digital and DTS have a channel specifically designed to take advantage of a subwoofer. Any sound system, even stereo and mono, sounds so much better with a subwoofer.

 

All should be voice-matched. No matter what kind of system you have, the speakers should sound the same. Just as your right and left speakers should be acoustically similar, so should the rest of the speakers in your system. The reasoning here is common sense: As sounds move around you, they should sound the same.