163Surround back speakersThe THX Surround EX format adds new “Surround Back” (SB) channels to the conventional 5.1-channel system. This makes it easy to achievesound positioned directly behind the listener, something that was previously difficult with sources designed for conventional multi surroundspeakers. In addition, the acoustic image extending between the sides and the rear is narrowed, thus greatly improving the expression of thesurround signals for sounds moving from the sides to the back and from the front to the point directly behind the listening position.FL CSW FR FL CSW FRSR chSL chSL ch SR chSB chChange of positioning and acoustic imagewith 5.1-channel systemsSpeaker(s) for one or two channels are required in order to achieve a THX Surround EX system with the AVC-A1XV. Adding these, however, allowsyou 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 recordedin conventional Dolby Surround as well as Dolby Digital 5.1-channel and DTS Surround 5.1-channel sources. Furthermore, all the Denon originalsurround modes (see page 142) are compatible with 7.1-channel playback, so you can enjoy 7.1-channel sound with any signal source.Movement of acoustic image from SR to SLChange of positioning and acoustic imagewith THX Surround EX systemMovement of acoustic image from SR to SB to SL2 Number of surround back speakersWith THX Surround EX, the surround back channel consists of one channel of playback signals, but we recommend using two speakers. Whenusing 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 backchannel when listening from a position other than the center.2 Placement of the surround left and right channels when using surround back speakersUsing surround back speakers greatly improves the positioning of the sound at the rear. Because of this, the surround left and right channelsplay 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 amovie theater the surround signals are also produced from diagonally in front of the listeners, creating an acoustic image as if the sound werefloating in space.To achieve these effects, we recommend placing the speakers for the surround left and right channels slightly more towards the front thanwith conventional surround systems. Doing so sometimes increases the surround effect when playing conventional 5.1-channel sources in theTHX Surround EX mode. Check the surround effects of the various modes before selecting the surround mode.
