Side speakers?

I know what they do in a 7.1 system. I know in a real movie theatre there are many side speakers to give an enveloping sound. My question: what channel is sent to side speakers when a movie is in 5.1??? What do they send to the side speakers in a real movie theatre? Is it a softened version of the L and R channel? Is is a blend of the rear and L or R channel?

I am planning to go to a 7.1 system in my HT but I am wondering what use the sides will be with 5.1 material?

Yeah, i hear ya
When 5.1 came out, it was a good thing. now everying is trying to expand it and have the latest and greatest, when in all reality they just make it more confusing.

one of the many reasons i stick with 5.1
At this stage of my system i agree with slappy. At one time I had a 10 channel system with 3 sets of Polk SRT s two extra SRT sub enclosures and 4 top of the line Polk bipoles ; two in the very back spaced 4 feet apart and two above my head for height illusion . Each speaker had an Adcom 555 11 in mono for 600 watts . The Lexicon MC 12 ran it all. For theatre it was a visceral experience i will not forget. I now focus on a natural , effortless musical mulltichannel environment and have found 5.1 works best , for me at least . The meridian 861 was a real eye opener and i discovered a simpler more rewarding path.
I saw in one post the mention of THX and it calling for mono-pole speakers, from what I understand only a dipole spaker is truely a THX surround compliant speaker, now you dont need these in the back, it would help but not needed, but for the sides dipole is THX standard, atleast im fairly sure of it...good thread though...p.s. I dont have the 8 ft behind my couch, I run 7.1 and found that with my Rotel processor the effects sound better when I set up the digital delay for 10 feet for the center backs...just personal preference.
For 7.1, the side speakers should be placed at plus and minus 90 degrees; i.e., directly to the sides of the primary listening area, not behind the listening area. The rear speakers ahould be placed at about 150 degrees; i.e., spread out on the back wall away from the centerline.

From my own experience, 7.1 provides a much more enveloping surround environment than 5.1.

Regarding 6.1 sources, there are one discrete and two matrix formats. Notwithstanding this, the material should be played back on a 7.1 speaker array rather than a 6.1 speaker set up. One reason is to avoid the potential for back to front reversal if a single rear spealker is placed on the centerline. Another is it spreads out the rear channel information as the rear is not intended to be a point source like the front center channel.

Since ther are no 7.1 sources available, at least at this time (high def DVDs may include 7.1 audio tracks?), you need to apply some type of processing to either 5.1 or 6.1 sources to best enjoy a 7.1 setup.

Some Prepros simply replicate the suround information in both the side and rear channels, but I don't consider this very desireable.

Lexicon has long provided 7.1 processing with Logic7, and now DPLIIx is a viable alternative. In either case, these processes wil take the original surround information and redistribute that surround information across discrete side and rear speakers, generating stereo rears. For more details on exactly what happens, I suggest going to and looking for posts by sanjay.

Hope this helps,