Yamaha DSP-Z9 Owner's Manual page 117

THX Cinema processing
THX is an exclusive set of standards and technologies
established by the world-renowned film production
company, Lucasfilm Ltd. THX grew from George Lucas'
personal desire to make your experience of the film
soundtrack, in both movie theatres and in your home
theatre, as faithful as possible to what the director
intended.
Movie soundtracks are mixed in special movie theatres
called dubbing stages and are designed to be played back
in movie theatres with similar equipment and conditions.
This same soundtrack is then transferred directly onto
Laserdisc, VHS tape, DVD, etc., and is not changed for
playback in a small home theatre environment.
THX engineers developed patented technologies to
accurately translate the sound from the movie theatre
environment into the home, correcting the tonal and
spatial errors that occur. On this product, when the THX
indicator is on, THX features are automatically added in
Cinema modes (e.g. THX Cinema, THX Surround EX).
Re-Equalization
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. Re-Equalization restores the
correct tonal balance for watching a movie soundtrack in a
small home environment.
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, you use only two speakers located
to the 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. This
can make the surround speakers 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.
A.S.A. (Advanced Speaker Array)
ASA is a proprietary THX technology which processes
the sound fed to 2 surround and 2 surround back speakers
to provide the optimal surround sound experience. When
you set up your home theater system using all eight
speaker outputs (Left, Center, Right, Surround Right,
Surround Back Right, Surround Back Left, Surround Left
and Subwoofer), placing the two Surround Back speakers
close together facing the front of the room as shown in the
diagram will provide the largest sweet spot. If for practical
reasons you have to place the Surround Back speakers
apart, you will need to go to the THX Audio Set-up screen
and choose the setting that most closely corresponds to the
speaker distance, which will re-optimize the surround
sound field. ASA is used in two new surround modes;
THX Ultra2 Cinema and THX Music Mode.
THX ULTRA2 CINEMA MODE
THX Ultra2 Cinema mode plays 5.1 movies using all 8
speakers giving you the best possible movie watching
experience. In this mode, ASA processing blends the side
surround speakers and back surround speakers providing
the optimal mix of ambient and directional surround
sounds. This mode permits the playback of a non
Surround EX/ES encoded 5.1 movie to be played back
over a 7.1 system. DTS-ES (Matrix and 6.1 Discrete) and
Dolby Digital Surround EX encoded soundtracks will be
automatically detected, if the appropriate flag has been
encoded. 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 manually
select the THX Surround EX playback mode, otherwise
THX Ultra2 Cinema mode will apply ASA processing to
provide optimum replay.
GLOSSARY
115