4
INTRODUCTION
unencoded sound, allowing a DTS music CD to provide over an hour of five-
channel music, at a quality indistinguishable from conventional CD.
THX
THX versions of Dolby Digital, MPEG Surround, and DTS are provided to
give a better match between the original soundtrack and typical domestic
listening conditions.
Multi-channel sources encoded onto two channels
Several systems have been developed for encoding multi-channel sources
onto a standard two-channel analogue signal so that they can be
reproduced by a conventional stereo system, or decoded with special
equipment for multi-channel reproduction. The 861 provides decoding of
the two most important of these, Ambisonic and Dolby Surround. Although
the channel separation cannot be as good as with the digital multi-channel
formats, the 861 produces excellent results with these formats.
Pro Logic
The Pro Logic preset is recommended for decoding Dolby Surround
encoded video and LaserDisc soundtracks, and films on television. Such
materials are usually identified by a Dolby Surround symbol on the
packaging, or displayed on the film before the programme.
TV Logic
TV Logic provides user-adjustable steering, and is recommended for use
with TV broadcasts that are not surround encoded, where Pro Logic may
give reduced intelligibility.
THX Cinema
THX Cinema enhances Pro Logic to replicate the sound of a dubbing
stage or theatre, whether or not the other equipment in your system is THX
approved.
Ambisonic
Ambisonic decodes material specifically encoded for surround sound
reproduction, using a two-channel stereo-compatible encoding. Recordings
encoded in Ambisonic format are available on CD from several sources
including Nimbus Records and York Ambisonic. Some radio broadcasts are
also broadcast in Ambisonic format.
Conventional stereo sources
The Digital Surround Controller can also accept a conventional two-channel
source, such as music on compact disc or a video soundtrack, and by
analysing the information in the signal separate the two-channel recording
into multiple channels to give better reproduction and a more stable
spatial image.
