THX Surround EX and Surround ES
Surround EX is a joint development of Dolby Laboratories and the THX division of Lucasfilm Ltd. In a movie theatre, film soundtracks that have been encoded with Surround EX technology are able to reproduce an extra channel which has been added during the mixing of the programme. This channel, called surround back, places sounds behind the listener in addition to the front left, centre, front right, surround left, surround right and LFE channels.This additional channel provides the opportunity for more detailed imaging behind the listener and brings more depth, spacious ambience and sound localization than with simple 5.1 reproduction. Movies that were created using the Surround EX technology, when released into the home consumer market may exhibit wording to that effect on the packaging.
With appropriate material, the THX Surround EX mode will normally activate automatically, providing this option has been enabled in the ‘THX Settings’ page of the Setup Menu. Some Dolby Digital Surround EX soundtracks are missing the digital flag that allows automatic switching. If you know that the movie that you are watching is encoded in Surround EX, you can select the THX Surround EX playback mode manually.
You can also switch on the THX Surround EX mode during the playback of 5.1 channel material that is not Surround EX encoded. In such case the information delivered to the surround back channels will be
THX MusicMode
For the replay of multichannel music the THX MusicMode can be selected. In this mode THX ASA processing is applied to the surround channels of all 5.1 encoded music sources such as DTS and Dolby Digital to provide a wide stable rear soundstage.
DSP EFFECTS MODES
The AV8 has a number of effects modes that can be used to enhance a stereo signal and to make use of the surround loudspeakers. DSP effects modes are only available with stereo source signals.
You can listen to the influence of any effect mode by playing a CD, then pressing pause, when the decaying reverberation effect can be heard.
Available effects modes
Music: Music surround makes full use of the additional speakers placed at the centre, sides and rear of the room. This effect uses ambiance extraction for the side and rear speakers and offers the most subtle surround processing with no reverberation or reflections.
Party:The Party effect allows unprocessed stereo signals to be played over all speakers for background music or for maximum acoustical output of the system.
Club: The Club effect generates reflections and short reverberation information to the front, side and rear speakers. It simulates a small club venue, such as a Jazz Club.
Concert Hall: The Concert Hall effect generates the ambient information for the simulation of a medium size hall. Reflections and medium length reverberation information are sent to all channels.
Sports: Sports stadium effect is ideal for use when watching live sports events which would normally be in stereo. The open ambience of a sports stadium is actively recreated around you, except from the centre channel which is kept clear for commentary.
Church: The Church effect uses a reverberation algorithm which emphasises rich, smooth reverberant decay in large spaces. As its name suggests, it works well for simulating a space with long reverberation time relative to its size, such as a large church or cathedral.
ABOUT THX® CINEMA PROCESSING
THX TECHNOLOGY
The tonal balance of a film soundtrack will be excessively bright and harsh when played back over audio equipment in the home because film soundtracks were designed to be played back in large movie theatres using very different professional equipment.
Timbre Matching™
The human ear changes our perception of a sound depending on the direction from which the sound is coming. In a movie theatre, there is an array of surround speakers so that the surround information is all around you. In a home theatre there are usually only two speakers located at either side of your head.The Timbre Matching feature filters the information going to the surround speakers so that they more closely match the tonal characteristics of the sound coming from the front speakers. This ensures seamless panning between the front and surround speakers.
Adaptive Decorrelation™
In a movie theatre, a large number of surround speakers help create an enveloping surround sound experience, but in a home theatre there are usually only two speakers. Two surround speakers can sound like headphones that lack spaciousness and envelopment. The surround sounds will also collapse into the closest speaker as you move away from the middle seating position.Adaptive decorrelation slightly changes one surround channel’s time and phase relationship with respect to the other surround channel.This expands the listening position and creates
–with only two speakers – the same spacious surround experience as in a movie theatre.
ASA (Advanced Speaker Array)™
ASA is a proprietary THX technology which processes the sound fed to two surround and two surround back speakers to provide the optimal surround sound experience. ASA is used in two modes;THX Ultra2 Cinema and THX MusicMode.
THX STANDARDS
Lucasfilm define a series of technical performance standards that equipment must exceed before it is awarded THX certification. Several levels of performance standards are defined, the most demanding standards are set for THX Ultra2. THX Ultra2 requirements cover every aspect of the product including
Before any home theatre component can be THX Ultra2 certified, it must incorporate all the technology features above and also pass this rigorous series of quality and performance tests. Only then can a product feature the THX Ultra2 logo, which is your guarantee that the home cinema products you purchase will give you superb performance for many years to come.
A list of available DVD software titles encoded with Dolby Digital Surround EX technology can be found at www.thx.com and www.dolby.com.
