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Additional Information
Surround back speakers
The THX Surround EX format adds new “Surround Back” (SB)
channels to the conventional 5.1-channel system. This makes
it easy to achieve sound positioned directly behind the
listener, something that was previously difficult with sources
designed for conventional multi surround speakers. In
addition, the acoustic image extending between the sides and
the rear is narrowed, thus greatly improving the expression of
the surround signals for sounds moving from the sides to the
back and from the front to the point directly behind the
listening position.
Change of positioning and acoustic image
with THX Surround EX system
Movement of acoustic image from SR to SB to SL
Speaker(s) for one or two channels are required in order to
achieve a THX Surround EX system with the AVR-4806.
Adding these, however, allows you to achieve stronger
surround effects not only with sources recorded in THX
Surround EX, but also with conventional 2- to 5.1-channel
sources. The WIDE SCREEN mode is a mode for achieving
surround sound with up to 7.1 channels using surround back
speakers, for sources recorded in conventional Dolby
Surround as well as Dolby Digital 5.1-channel and DTS
Surround 5.1-channel sources. Furthermore, all the Denon
original surround modes ( page 60) are compatible with
7.1-channel playback, so you can enjoy 7.1-channel sound
with any signal source.
2Number of surround back speakers
With THX Surround EX, the surround back channel
consists of one channel of playback signals, but we
recommend using two speakers. When using dipolar
speakers in particular, it is essential to use two speakers.
Using two speakers results in a smoother blend with the
sound of the surround channels and better sound
positioning of the surround back channel when listening
from a position other than the center.
2Placement of the surround left and right
channels when using surround back speakers
Using surround back speakers greatly improves the
positioning of the sound at the rear. Because of this, the
surround left and right channels play an important role in
achieving a smooth transition of the acoustic image from
the front to the back. As shown on the diagram above, in
a movie theater the surround signals are also produced
from diagonally in front of the listeners, creating an
acoustic image as if the sound were floating in space.
To achieve these effects, we recommend placing the
speakers for the surround left and right channels slightly
more towards the front than with conventional surround
systems. Doing so sometimes increases the surround
effect when playing conventional 5.1-channel sources in
the THX Surround EX mode. Check the surround effects of
the various modes before selecting the surround mode.
