19. What components are necessary to upgrade from Dolby Digital EX/Dolby Pro Logic II to Dolby
Pro Logic IIx?
Aside from an A/V processor equipped with the new Dolby Pro Logic IIx algorithm, you would
need an additional amplifier and an additional speaker matched to the existing back speaker for
full integration of Dolby Pro Logic IIx.
Most A/V receivers equipped with Dolby Pro Logic IIx, on the other hand, will include the addition-
al amplifier necessary to upgrade from 6.1 Dolby Digital EX to 7.1 channel Dolby Pro Logic IIx.
Would You Like to Know more About THX?
Please read the following explanation written by THX Ltd. It will help you understand and appreciate
the substantial technical advantages and sonic benefits of THX technology.
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.
TECHNICALLY SPEAKING continued
16
