All of these systems are extensions of the existing Dolby Digital 5.1 and DTS 5.1 digital surround sound formats. Users with one center back speaker (a 6.1 configuration) or two center back speakers (a
7.1configuration) can take advantage of this extended surround information. On traditional 5.1 channel systems, Dolby Digital Surround EX or DTS-ES 6.1 discs sound exactly the same as 5.1 channel discs in each respective format.
If you have configured your system with one or two center back speakers, decoding of DTS-ES discs is automatic, just as it is with standard DTS soundtracks. Likewise, decoding of Dolby Digital Surround EX discs is automatic with one exception. Some Surround EX titles do not have the detection “flag” encoded on the disc. To activate the Dolby Digital Surround EX features for these discs (or for standard 5.1 channel Dolby Digital discs), you must manually activate Dolby Surround EX processing.
Dolby Pro Logic IIx 6.1 and 7.1 Channel Surround
The latest technology from Dolby uses advanced matrix decoding for the surround channels in a 6.1 channel or 7.1 channel system. Working with any 2.0 channel or 5.1 channel recording, Dolby Pro Logic IIx processing distributes the surround channel information among three or four surround channels, with a Music mode optimized for musical recordings and a Cinema mode optimized for film soundtracks.
Rotel XS6.1 and 7.1 Channel Surround
This receiver also features Rotel XS (eXtended Surround) processing provides extended surround performance on 6.1 and 7.1 channel systems. The key benefit of Rotel XS is that it works at all times with all multichannel digital signals, even those that might not otherwise activate Dolby Digital EX or DTS-ES surround decoding for the center back channel(s). Always available when center back speaker(s) are configured in the system setup, Rotel XS decodes the surround channels and distributes the extended surround channels to the center back speaker(s) in a way that tends to create a diffuse surround effect. Rotel XS works with matrix-encoded surround signals (such as non-flagged DTS-ES and Dolby Surround EX discs) as well as digital source material that is not Dolby Surround EX encoded (such as DTS 5.1, Dolby Digital 5.1, and even Dolby Pro Logic II decoded Dolby Digital 2.0 recordings).
Dolby Digital Plus
Built on Dolby Digital, the multichannel audio encoding standard for DVD and HD broadcasts, Dolby Digital Plus was designed for the new high-resolution delivery formats, but remains compatible with current A/V receivers. It is supported by the HDMI digital connection standard. Dolby Digital Plus can provide up to 7.1 channels with discrete channel output at higher bitrates than Dolby Digital. Dolby Digital Plus is an optional sound format for Blu-ray, and a mandatory inclusion for HD DVD discs.
Dolby True HD
Dolby TrueHD is based on lossless coding technology to deliver studio master-quality sound. Dolby TrueHD supports up to eight full-range channels (the maximum allowed by Blu-Ray) of 24-bit/96 kHz audio. Dolby TrueHD is supported by the HDMI v1.3 digital connection. Additional features include Dialogue Normalization, which maintains the same volume level when changing to other Dolby Digital and Dolby TrueHD programming, and Dynamic Range Control (or ‘Night Mode’), reducing peak volume levels to allow late-night viewing of high-energy surround sound without disturbing others. Dolby TrueHD is an optional sound format for Blu-ray Disc, and a mandatory format for HD DVD.
DTS-HD Master Audio and DTS-HD High Resolution Audio
Like Dolby’s TrueHD, DTS-HD Master Audio is an advanced lossless audio codec which is an optional sound format for Blu-ray discs, again delivering the original recorded sound ‘bit-for-bit’. It is also an optional format for HD-DVD disc recordings. DTS-HD Master Audio is compatible with the HDMI v1.3 connection standard, and supports a maximum of 192kHz sampling at 24-bit depth in two-channel mode, and 24bit/ 96KHz resolution for eight channels in multichannel mode. A DTS-HD capable receiver can also decode discs recorded with DTS-HD High Resolution Audio. This format is not lossless but delivers virtually all of the original recording, though not literally identical to the studio master.
DSP Music Modes
Unlike all of the formats mentioned above, the receiver offers four surround modes that are not part of a specific recording/playback system. These modes (DSP 1–4) use digital signal processing that adds special acoustic effects to any signal. DSP processing can be used with Dolby Surround recordings, Dolby Digital recordings, CDs, radio broadcasts, or any other source material; however, typically DSP settings would be used with source material for which there is no specific surround decoder.
The four DSP MODES in the receiver use digital delay and reverberation effects to simulate progressively larger acoustic environments with DSP 1 being the smallest type of venue (such as a jazz club) and DSP 4 being a large venue (such as a stadium). Typically used to add ambience and a sense of space when listening to music sources or other sources that lack surround sound encoding..
2CH/5CH/7CH stereo formats
The receiver also provides four modes that disable all surround processing and deliver stereo signals to amplifiers and speakers. The four options are:
2CH Stereo: Turns off the center channel and all surround channels in the system and delivers a conventional 2-channel signal to the front speakers. If the system is configured to route bass signals from the front speakers to the subwoofer, this capability remains in effect.
Analog Bypass: For 2-channel analog inputs, there is a special stereo mode that bypasses ALL of the receiver’s digital processing. The two front speakers receive pure analog stereo full-range signals with no subwoofer crossover, no delay, no level adjustments, and no contour adjustment.
5CH Stereo: Distributes a stereo signal to 5.1 channel systems. The left channel signal is sent, unchanged, to the front left and surround left speakers. The right channel is sent to the front right and surround right speakers. A mono sum of the two channels is sent to the center channel speaker.
7CH Stereo: This mode is the same as 5CH Stereo described above except that it also distributes stereo signals to center back speaker(s) installed in the system.
Other Digital Formats
Several other digital formats are not surround sound formats at all, but rather systems for digital 2-channel recordings.
PCM 2-channel: This is an uncompressed 2-channel digital signal such as that used for standard CD recordings and some DVD recordings, particularly of older films.
