Rotel RSX-1056 Overview of Surround Formats, Dolby Surround Dolby Pro Logic, Dolby Digital

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Overview of

Surround Formats

To get the best performance from your RSX-1056, it helps to understand the many surround sound formats available today, to know which decoding process to use for a particular recording, and how to select it. This section provides basic background informa- tion about surround sound formats. The follow- ing sections provide detailed operating instruc- tions for automatic and manual selection of surround modes.

NOTE: The RSX-1056 has built-in amplifiers to drive five speakers in a 5.1 channel system. To use surround modes for 6.1 or 7.1 chan- nel systems, you will need a separate power amplifier to drive one or two speakers.

Dolby Surround

Dolby Pro Logic II

The most widely available surround sound format for consumer audio/video is Dolby Surround®, available on nearly all commer- cial VHS tapes, many television broadcasts, and most DVDs. Dolby Surround is the con- sumer version of the analog Dolby Stereo system first introduced in the film industry in 1972. It is a matrix-encoding system that records front left, front center, front right, and a mono sur- round channel into a 2-channel stereo record- ing. During playback, a Dolby Pro Logic® or Pro Logic II decoder extracts each channel and distributes it to the appropriate speakers.

The original Dolby Pro Logic decoder deliv- ered a mono signal with reduced high-fre- quency content to the surround speakers. A more advanced decoder in the RSX-1056, Dolby Pro Logic II, increases the separation and frequency response of the surround chan- nels for significantly improved performance with Dolby Surround encoded recordings.

Dolby Pro Logic II decoding should be used for any analog recording labeled “Dolby Sur- round” or any Dolby Digital 2.0 soundtrack. Dolby Pro Logic II does a superb job deriving surround sound from conventional 2-channel stereo recordings, using phase relationships to extract front, right, center, and surround chan- nels. A “music mode” makes Pro Logic II an excellent choice for audio CDs.

Dolby Digital

In 1992, a digital recording system, called Dolby Digital, was first used in the film indus- try. Dolby Digital is a recording/playback sys- tem that uses compression techniques to store large amounts of audio data efficiently, much like the JPEG format stores large photographs in small files on a computer. Because it is capable of performance beyond that of au- dio CDs and can tailor its output for a wide ranges of system configurations, Dolby Digi- tal is the standard audio format for DVDs and for digital television broadcasting in the United States.

The Dolby Digital system can be used to record up to six discrete audio channels, but can also be used for fewer. For example, a Dolby Digital

2.0soundtrack is a digital 2-channel record- ing of a matrix encoded Dolby Surround soundtrack.. To play a Dolby Digital 2.0 re- cording, use Dolby Pro Logic II decoding as previously described.

The most common use of Dolby Digital in newer films, in both the film industry and in home theater, is Dolby Digital 5.1. Instead of encoding multiple surround channels on a two-channel recording, Dolby Digital 5.1 records six dis- crete channels: front left, front center, front right, surround left, surround right, and a Low Fre- quency Effects (LFE) channel containing ultra- low bass signals intended for a subwoofer. A Dolby Digital decoder extracts the channels from the digital bitstream, converts them to analog signals and routes them to the appro- priate amplifiers and speakers. All channels provide full frequency response with total sepa- ration between all channels and large dynamic range capability. A Dolby Digital 5.1 soundtrack can provide more impressive sur- round sound than matrix Dolby Surround.

Decoding of Dolby Digital 5.1 soundtracks is automatic. When the RSX-1056 detects a Dolby

5.1signal on one of its digital inputs, it acti- vates the proper processing. Keep in mind that Dolby Digital is only available from digital sources (a DVD, a LaserDisc, or a Digital TV/ Cable/SAT tuner). Also, you must connect the source with a digital cable (coax or optical) to an active digital input on the RSX-1056.

NOTE: Many DVDs have a Dolby Digital 2.0 matrix soundtrack as the default, which should be decoded with Pro Logic II. The Dolby Digi- tal 5.1 soundtrack may have to be selected as an option from the setup menus at the be- ginning of the DVD. Look for a Dolby Digital

5.1selection under “Audio” or “Languages” or “Setup Options” when you insert the disc.

DTS 5.1

DTS 96/24

DTS® (Digital Theater Systems) is an alterna- tive digital format competing with Dolby Digital in both movie theaters and home theater markets. The basic functions of the DTS sys- tem are similar to those of Dolby Digital (for example, 5.1 discrete channels), however the technical details of the compression and de- coding processes differ somewhat and a DTS decoder is required.

A recent extension of the DTS encoding sys- tem is DTS 96/24. These recordings provide the performance of a 96kHz sampling rate while still using actual 48kHz sampling rate of standard DTS discs.

Like Dolby Digital, DTS can only be used on a digital recording and, therefore, is only available for home use on LaserDiscs, DVDs, or other digital formats. To use the RSX-1056’s DTS decoder, you must connect your DVD player to the RSX-1056’s digital inputs.

As with Dolby Digital 5.1, detection and proper decoding of DTS 5.1 signals is automatic.

NOTE: DVDs with a DTS soundtrack almost always have it configured as an option to the standard matrix Dolby Surround format. To use DTS, you may have to go to the setup menus at the beginning of the DVD and se- lect “DTS 5.1” instead of “Dolby Surround” or “Dolby Digital 5.1”. In addition, many DVD players have the DTS digital bitstream turned off by default and cannot output a DTS soundtrack (even if selected on the disc’s menu) until you activate the player’s DTS out- put. If you hear no sound the first time you attempt to play a DTS disc, go to the DVD player’s configuration menus and turn on the DTS bitstream. This is a one-time setting and need only be done once.