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Discussion Starter · #1 ·
Hi guys, I'm having a bit of a tough time adding 2 back surround speakers to my existing 5.1 system. My Sofa is backed up right against the wall and due to the constraints of the room I can't move the sofa up off the wall more than a few inches.


In ceiling speakers wouldn't be very easy to implement as I don't have access to the attic. As far as in wall speakers go I'm concerned that given the small space between the wall and couch I won't get the desired effect.


I have also heard that mounting two speakers on the wall and facing them down is not a very good solution either and it also wouldn't go over very well at my house due to WAF. I have heard some comment that placing two speakers on the floor behind the couch facing up can produce a decent alternative in some situations.


I would appreciate if anyone who has tried some of these options can comment on how well it works and whether in this situation going to a 7.1 system is actually worth it. I have already purchased two Polk Rti38's for this purpose but I could use them for zone 2 if it doesn't work out.
 

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I had a similar situation where the back surrounds could not be placed ideally. For me it was that they could not be centered exactly behind the seating positions. After trying really hard to like the way it sounded with the rear centers I reluctantly put the speakers in the gargage and stuck with 5.1.

If you already have the speakers, try different things. I have heard of success where people put them behind the couch facing up.

Don't be afraid to accept the fact that 5.1 may sound better in your situation. I know that it was very hard for me to mentally accept. I really wanted to like the extra speakers. Every room is different and not textbook.

Greg
 

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When we get a new receiver to replace our defective 6.1 one, we're going to mount that sixth speaker right on the rear wall pretty close to the ceiling. The couch will be right against the back wall, too (PAF - parents' acceptance factor). We'll try to buy a shelf w/ a lip so that the 6th speaker can be angled downwards (slightly). Hopefully it'll sound OK. : \\
 

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My couch is right against the wall.

I'm using NS-333's (2) for the center back channel.

My plan is to get a sort of 'sofa table' to put behind the couch to have the speakers sit on that right behind the heads of the listeners. Not ideal, but nowhere else to go.

I thought maybe on the floor behind the couch facing eachother set a tad further apart to get a good center sound field, but that will probably interfere with storage below the table which was my second idea for having a 'ledge/shelf' behind the couch.


Seth
 

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Dolby's site shows alternate surround speaker placement diagrams. Even though placing a surround 3 or more feet above the listeners head is ideal to minimize localization, you could place the rear surrounds on stands and only raise them to the top of the sofa. This will enhance the WAF and still provide some rear ambiance.
 

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IMO it is foolish to try to implement a 7.1 system in a room that can't accommodate it. You absolutely need space behind the listening position for the surround back speakers. I guarantee you that a well positioned 5.1 system will trump a poorly set up 7.1 system. Don't waste your time or money unless you have the right room.
 

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Just FYI my 5.1 system is great.

The two side surrounds are positioned at ear level (floor standers) about 4 feet from the couch at the same line as the listener just slightly back. They already produce a semi-stereo effect behind the listener even though there is no speaker there.

I have the pots on my receiver for a 6.1/DTS ES so I figured I'd throw in 2 more spekaers.


Seth
 

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I know Dolby does not recommend placing surrounds on the wall, but what is the best of their four options. I have no side wall to the left and a bookcase mounted into the end wall to the right that flanks a fireplace. Would the Axiom surrounds mounted directly to the wall above listening level be the most ideal?? Or would mounting to the wall above listening level facing each other with a bookshelf speaker be better. I would really rather not have stands as I plan on adding a reclining couch and they would probably end up getting knocked over.
 

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Quote:
Originally posted by Mit07
IMO it is foolish to try to implement a 7.1 system in a room that can't accommodate it. You absolutely need space behind the listening position for the surround back speakers. I guarantee you that a well positioned 5.1 system will trump a poorly set up 7.1 system. Don't waste your time or money unless you have the right room.
How much space should there be between the rear speakers and the couch?
 

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I would not say that is a hard and fast rule. Sure a larger room, with tall ceilings is nice, but commercial theaters may cause one to sit on the back row and the rears are right behind them (but higher than ear level).
 

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Considering that there is so little source material with rear content (most people are using synthesized rears), save your shekels.
 

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Well surround effects from surround sound formats are sent to not only the sides, but the rears. This is why commerical theaters (newer ones) use side and rear surrounds.
 

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Meaning what? That the rears aren't synthesized (or "derived")? What home media exists in native 7.1?


As for theaters, not all use rears, and >90% of the audience is sitting well in front of them when used. (They also use many sides, as many as 5 front channels, and time delay processors.)


Don't get me wrong. I appreciate my rears. But if I didn't have room behind my listening position, I wouldn't use them. I doubt I'd be able to distinguish them from the sides, and there's no discrete material (yet) that I need them to produce.
 

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Good point, no discrete 8-channel encoding. I use Logic 7 (Lexicon) where there is panning and movement of the sound from one surround to the next and it can steer those sounds independently between all 4 surround speakers. I am with Russ Hershellman that it is hard to be surrounded by sound with only 2 speakers. I need to get to bed, talk in the morning.
 

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I'm in the exact same boat, so here's what I did:


I purchased a pair of Polk FXi30's http://www.polkaudio.com/home/produc...15e9beac6ed4c7


And I reversed the mounting, I put the one labelled "Left" on the right and vice versa, wall-mounted them 2' to either side of my couch. I reversed them so both the driver and the tweeter face inward instead of reflecting them off a side wall. It sounds GREAT! I was worried that it would sound like it's coming from the left and right of you, but with TXH-EX it sounds like it is coming from behind you, which is what I was hoping for.
 

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Also, Dolby's new PLIIx matrix decoder is similar to Lexicon's Logic 7 for re-creating stereo rear effects and is in serious competition to it.
 

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Quote:
Originally posted by DMF
I doubt I'd be able to distinguish them from the sides...
You might not be able to distinguish sounds coming from behind you vs sounds appearing at your sides. For those of us that can, a 7.1 speaker configuration has three important advantages over a 5.1 set-up. The first is better envelopment: 4 speakers surround you better than 2 can. Next is better localization in the surround field: sounds can be localized to your left, your right, behind you, or any combination thereof. And finally, you get much better stability when it comes to imaging: for example, no matter where you sit on your couch, sounds intended to come from behind you will always appear to come from that direction. No magic involved - just actual speakers placed behind you (makes it hard for those sounds to come from anyplace else).
Quote:
...and there's no discrete material (yet) that I need them to produce.
While there is no discrete 7.1-channel content available for consumers, surround processing such as PLIIx and LOGIC7 can do a great job of taking 5.1-channel soundtracks and spreading the 2 surround channels over 4 surround speakers. More often than not, the results of the processing are tasteful and natural sounding. Some surround information (ambient sounds) are better heard from the sides while other surround effects (flyovers) sound better from behind. How do you accomplish this kind of stable side vs rear imaging when using only 2 surround speakers? You can't. It's only possible when the 2 surround channels are steered over 4 speakers. Side vs rear surround content doesn't have to be discrete; it just has to be done well.


Best,

Sanjay
 

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Quote:
Originally posted by EVT
My Sofa is backed up right against the wall and due to the constraints of the room I can't move the sofa up off the wall more than a few inches....I have heard some comment that placing two speakers on the floor behind the couch facing up can produce a decent alternative in some situations.
That's exactly what I would do if I were in your situation. The rear speakers remain hidden (high WAF factor) but their sound doesn't. I've heard a couple of systems set up that way and, while they weren't optimal, they did sound better than their 5.1 counterparts. The speakers behind the couch bathe the rear wall in a wash of sound; it sound more fuzzy than distinct, but the sounds do appear to come from behind you - as opposed to your sides (which is the effect you're looking for).
Quote:
I have already purchased two Polk Rti38's for this purpose but I could use them for zone 2 if it doesn't work out.
Well hell, if you've already got the speakers then listen for yourself to see if 7.1 is worth it in your room. Just place the speakers behind the couch temporarily (don't even bother dressing the speaker cables), and play a variety of familiar material in PLIIx mode or even using EX/ES decoding. If you like the effect, cut the cables to length and make the speaker placement permanent. If you don't hear any benefit over your current 5.1 set-up, then send the extra pair of speakers to Zone 2. Either way, trust your ears to judge whether you like the results or not (none of us can decide this for you).


Good Luck,

Sanjay
 

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Sanjay, you are the man!
 

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Discussion Starter · #20 ·
Thanks for the replies guys. I set up the RTi38's behind my couch and the difference from 6.1 was immediately noticable. Even in EX/ES mode the difference is very noticable. I spread out my speakers about 5 feet (from tweeter to tweeter) and it sounds great, the improvement in imaging from 6.1 to 7.1 is obvious.


Also, Dolby Pro Logic IIx is very effective, you really get the sensation of stereo between the surround back speakers.
 
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