�Why Direct Radiating Speakers for the DD-5.1 Surrounds?�
From Dolby Labs:
Dolby Digital Professional Encoding Manual
(http://www.dolby.com/digital/encodvw.pdf) - No Longer Available from website

2.3.2 Surround Speakers
"Full range, direct radiator speakers are highly recommended for Surrounds.  They may either be identical or similar in design to the Center or Left and Right speakers."
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2.4.2 Surround Speaker Placement
"For installations using one set of speakers, typically the speakers will be located approximately two feet behind the engineer's position, at or above ear level and angled (read my comments below) so as to focus either directly overhead or on axis to the engineer."
(My comments: The above recommendation is for the Mixing Sound Engineers only - where the Sound Engineer is more concern with the accurate details of which distinct sounds effects will pan and add impact to what's viewed on the screen.  For home and Cinema Theater application, it would  required the widest dispersion spread as possible for the audience, hence, pointing the speakers towards each other as recommended below)
Click for Dolby's entire "Surround SPKR Placement" article
Preferred surround placement
Location
"If possible, place surround speakers to either side of the listening area, not behind it."
Click for Dolby's entire "Surround SPKR Placement" article
Height
"If space permits, install surrounds 2-3 feet above viewers. This helps to minimize localization effects."
Click for Dolby's entire "Surround SPKR Placement" article
Aiming
"Aiming surrounds straight across the room, not down at viewers, helps create a more open, spacious surround soundfield."
Want to read my thoughts on why Dolby Lab's did not recommend 'Dipoles' for surrounds???
Click for "Why not Dipoles?"
Click to see webpage
Dolby's Typical 5.1-CH Room Layout vs. HT Room Layout
I use direct-radiating (mono-pole) speakers located 3 feet behind (like the Mixing Eng. Studio & because I have the room) my REF Calibration location (Main HT - REF Loc. 9' from Center) and 7' feet high from the floor, on the side walls pointing @ each other. (20ft. x 30ft. w/10ft. high vaulted ceiling family room)
Two excellent DVD Demo's to verify setup and impress newbies to HT!

Dolby Digital 5.1 - 360 degree DVD Surround samples:
1) Video Essentials DVD - Narrator's voice "Walk Around the Room"
2) Dragonheart - Draco flying around Dennis Quaid while talking about the "Old Knights Codes"
So,  mount (if you can) your surround speakers on each side wall, facing each other, . . you may want to follow Dolby Lab�s diagram above, if your couch is in the room.

But, if your couch is on the back wall, move your surrounds forward until they are inline with the front edge of the couch.  This arrangement will locate it away from the back wall corners and should give some illusion of discrete sound above and possibly behind your 'sweet spot'.
Click to go to Video Essentials DVD Webpage
It should also seamlessly pan equally well with the front channels because as the sound moves from the front right channel, . . .then to the right rear surround, . . .your rear speaker baffle dispersion spread should easily blend with the rotating sound from the front right speaker baffle dispersion. 

The sound should be like the Cinema Theater's and Recording Engineer's Mixing Studio!
Specifically, your setup should reflect what the Mixing Engineer's hears, glorious detailed individual effects!
PI - Nov 18, 1999
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