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4. OPERATION continued …
4.8.4 DOLBY DIGITAL EX / PRO LOGIC IIx FOR 5.1 SOURCES
Dolby Digital EX and Pro Logic IIx can be used to decode DVDs encoded in Dolby Digital Surround EX by
extracting Rear channel information from the two Surround channels. Dolby Digital EX creates a mono Rear
signal, whereas with Pro Logic IIx, the two Rear channels play a stereo signal. Either one of these Modes
can be applied to any other 5.1-channel material. The Rear channels may or may not be pleasing depending
on the soundtrack.
A list of movies encoded in Dolby Digital Surround EX can be found on the Dolby web site at www.dolby.com
and on the THX web site at www.thx.com. Newer titles contain a flag that can automatically engage Dolby
Digital EX / Pro Logic IIx, whereas older titles do not. Press MODE when a movie starts playing and use the
Master Control Knob to select the Mode that sounds best – the display says “DOLBY D 5.1 INPUT” if the
soundtrack is unflagged, and “DOLBY D EX AUTO” if it is flagged.
4.8.5 DTS-ES
There are two ways that Rear channel information is encoded in DTS-ES – Matrix and Discrete:
• Matrix – DTS-ES Matrix movies contain a matrixed Rear channel. The AVM 50 automatically
engages Neo:6 to decode DTS-ES Matrix. Neo:6 can also be turned on manually and applied to any
other 5.1-channel material – when a movie starts playing, press MODE and use the Master Control
Knob to select. A mono Rear channel is derived from the Left and Right Surround channels. This
Rear channel may or may not be pleasing depending the soundtrack.
• Discrete – DTS-ES Discrete soundtracks contain 6.1 channels with an independent Rear channel.
The AVM 50 automatically engages DTS-ES Discrete decoding.
4.8.6 THX ULTRA2 / THX SURROUND EX
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, both in movie theaters and in your home theater, as faithful as possible to what the director
intended. Movie soundtracks are mixed in special movie theaters called dubbing stages and are designed to
be played back in movie theaters with similar equipment and conditions. This same soundtrack is very often
transferred to DVD, Laserdisc, VHS tape, etc. without any adjustments for playback in the smaller home
theater environment. THX engineers developed patented technologies to accurately translate the sound
from the movie theater environment into the home, restoring proper tonal and spatial balance.
Each THX mode includes a specific combination of the following:
• Re-Equalization – Restores the correct tonal balance for home playback. A film soundtrack may
sound too bright when played in the home, because film soundtracks are designed for large movie
theaters where acoustical properties are different. To enable or disable Re-EQ, press THX twice to
display “THX RE-EQUALIZATION”, then select On or Off with the Master Control Knob or
(up/down) on the remote control. You can even apply Re-EQ when THX is Off – this can be useful if
the high-pitched noise produced by standard CRT monitors accidentally leaked into the audio while
it was being recorded, and you would like to filter it out.
• 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. Timbre Matching, which includes Re-EQ, 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.
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