# Surround Back as Mono?



## gregsdouglas

Due to the shape of my home theater, I can't get stereo speakers to fit at the rear of the theater. I have an existing 7.1 setup on an Onkyo TX-NR929 with RSL's 5.1 set up and two Polk satellites at the top of my front soundstage, giving me the PL IIz setup. The Surround Left & Right speakers are located at the back left & right corners of the room. The layout is goofy and I simply can't move them up towards the seating area. 

I'm wondering if I could purchase an additional Center channel speaker and run that in the middle of the area directly behind the seating area (about 7' back, above a door, so the speaker would be elevated up at around 7', just like the Left & Right surrounds are. 

Was wondering if I could run the Surround Back channel using just the left binding posts and set the rear to Mono. Would that help the soundstage, or would the fact the Surround Rear would be literally just as far set back as the Surround Left & Right cause imaging issues?

Next house, I hope to have more options for placement, but I'm limited here and hoping to make the most of an imperfect situation. 

Any thoughts???

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## sdurani

One of the hallmarks of a 7.1-speaker layout is rear-vs-side separation in the surround field. If your side speakers are are in the back corners of the room, then placing a speaker between them won't sound like that speaker is further behind you. Better to stick to a 5.1-speaker configuration.


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## NBPk402

In the beginning of surround setups there used to be a mono rear channel option as I recall... I don't think any of the processors support a rear mono channel anymore though. The rear 2 channels are supposed to be away from the corners (I have to admit I am running mine in the corners now due to seating)... Do you have enough room to run 2 in the rear maybe 5' apart? Does your processor even support running a mono rear channel?


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## gregsdouglas

There is one possible way I could open up walls and rewire to get the separation, but the walls in my layout only come down from the ceiling about 7" (there's an opening to our wet bar beside the seating area.) It is possible to use that 7" space and wall mount the Left & Rear surrounds just behind the seating area, but they (and the resulting opened space at the back) would all (all four surrounds) be at 7' height with the satellites pointing down and in to the seating area. 

That kind of feels forced and I'm thinking I may be better off just waiting til we move... Or are the left & right surrounds okay to be elevated like that? It'd be pretty close to "the voice of God talking down" kind of thing. Right now with the L&R surrounds elevated but 7' back, tibia certainly not a problem.

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## sdurani

ellisr63 said:


> In the beginning of surround setups there used to be a mono rear channel option as I recall...


Yup, but the mono surround channel was sent to 2 surround speakers that were spread well away from the listener's centre line.


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## NBPk402

gregsdouglas said:


> There is one possible way I could open up walls and rewire to get the separation, but the walls in my layout only come down from the ceiling about 7" (there's an opening to our wet bar beside the seating area.) It is possible to use that 7" space and wall mount the Left & Rear surrounds just behind the seating area, but they (and the resulting opened space at the back) would all (all four surrounds) be at 7' height with the satellites pointing down and in to the seating area.
> 
> That kind of feels forced and I'm thinking I may be better off just waiting til we move... Or are the left & right surrounds okay to be elevated like that? It'd be pretty close to "the voice of God talking down" kind of thing. Right now with the L&R surrounds elevated but 7' back, tibia certainly not a problem.
> 
> Sent from my iPhone using HTShack


I think having the speakers that high would be fine but I would angle them down a bit. My current setup has a pair of floor standing speakers about 6" from the ceiling and they sound fine.

You could also hang your speakers from the ceiling or get a pair of ceiling mount speakers. In my last house I had ceiling speakers installed in our formal dining room and used them for the rears in a 7.1 setup.


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## tonyvdb

The only real benefit to rear sorround speakers is when you have two rows of seating and you have the side speakers forward even with the front row seating. I don't see any reason that a single centre speaker would function correctly in your situation.


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## gregsdouglas

Probably worth a try then. I confirmed. The manual does support an 8.1 setup using the left posts of the Surround Back channels, leaving the Right disconnected. Sounds like a go if I move the left & right surrounds forward. 

Although now that I see the manual confirming support, it does show a very narrow separation from L/R to Back channels - granted, the sofa is shoved way back in the picture. 

The wiring setup for 6.1 and 8.1 for Onkyos is also shown in the manual, as attached here. It would simply have "speaker 8" set up and no "speaker 7" as per their diagram....

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## NBPk402

gregsdouglas said:


> Probably worth a try then. I confirmed. The manual does support an 8.1 setup using the left posts of the Surround Back channels, leaving the Right disconnected. Sounds like a go if I move the left & right surrounds forward.
> 
> Although now that I see the manual confirming support, it does show a very narrow separation from L/R to Back channels - granted, the sofa is shoved way back in the picture.
> 
> The wiring setup for 6.1 and 8.1 for Onkyos is also shown in the manual, as attached here. It would simply have "speaker 8" set up and no "speaker 7" as per their diagram....
> 
> Sent from my iPhone using HTShack


Looking at the diagram... I don't see where it supports a 8.1 setup. I see 7.1 and 9.1 in the "speaker configuration" part.. I see where they are showing "7" by itself so I am unsure how hou would set your processor up for a 6.1 or 8.1.


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## Tonto

Can you post some pictures of your room?


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## gregsdouglas

ellisr63 said:


> Looking at the diagram... I don't see where it supports a 8.1 setup. I see 7.1 and 9.1 in the "speaker configuration" part.. I see where they are showing "7" by itself so I am unsure how hou would set your processor up for a 6.1 or 8.1.


The number of speakers deployed is the top horizontal row of the chart. Go across to 8 then follow down that column. You'll see a check mark beside "Surround back speaker" and the row under that ("Surround Back SpeakerS") is not checked. I used to own an tx-nr818 where page 13 showed a similar chart and specifically advised to use the left channel for a mono Surround Back in an 8.1 or 6.1 setup.

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## gregsdouglas

Tonto said:


> Can you post some pictures of your room?


Unfortunately I'm away for Canadian Thanksgiving so I can't right now. The room is 14' wide and 20' long with a drop ceiling/ceiling tiles hung at 7'. The seating area is just a reclining sofa at 13' back from the screen, directly under the projector. Immediately to the right of the seating area is a bar top that is open to an 11' x 12' wet bar - kind of like at a pub where you'd pull up a stool and belly up to the bar. It is solid to 36" height and open into the bar area for the length of the 4' bar top. There is a bulkhead for forced air ducting that's dry walled and forms a "top wall" that's 7" down from the drop ceiling above the bar. That's potentially where I could mount the L&R surrounds. 

Directly behind the seating area and 7' back is a door to the home office and laundry. The back-right corner is wide open for 36' and serves as the landing to the stairs leading down from the main floor. This is a basement theater.

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## NBPk402

gregsdouglas said:


> The number of speakers deployed is the top horizontal row of the chart. Go across to 8 then follow down that column. You'll see a check mark beside "Surround back speaker" and the row under that ("Surround Back SpeakerS") is not checked. I used to own an tx-nr818 where page 13 showed a similar chart and specifically advised to use the left channel for a mono Surround Back in an 8.1 or 6.1 setup.
> 
> Sent from my iPhone using HTShack


I saw that part, and what has me confused is below that it shows the different setups, and nowhere is a 6.1 or a 8.1 listed. What I am getting at is what are you going to setup your processor to since there is not a 6.1 or 8.1 listed?

Does your new receiver specifically advise youto use the left channel for a mono Surround Back in an 8.1 or 6.1 setup?


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## gregsdouglas

ellisr63 said:


> Does your new receiver specifically advise youto use the left channel for a mono Surround Back in an 8.1 or 6.1 setup?


Just found it now. Yes. It says to use the Left posts.

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## NBPk402

gregsdouglas said:


> Just found it now. Yes. It says to use the Left posts.
> 
> Sent from my iPhone using HTShack


There you go then... It should work fine then. My biggest concern was if the processor would convert the rear channels to mono and apparently yours will. Let us know how it works out. :T:T


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## gregsdouglas

ellisr63 said:


> There you go then... It should work fine then. :T:T


My initial concern was whether or not I'd need to move the L&R Surrounds away from the corners. I technically can move them, but when we're not watching movies, it'll look funny. May lose the "wife approval factor" that way. Haven't ordered the speakers yet (was going to double up on the sub at the same time...). Didn't want to be stuck with speakers I couldn't use, but I guess I could always Zone 2 them regardless....

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## Tonto

I say it will be best to go ahead & mount your surrounds on the 7" wall with a bracket & angle them down. And mount the rears on each side of the door on the back wall. Enveloping yourself in the soundfield is the whole point of HT. I say do the best you can with what you have. You can always change it back it it's horrible.


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## gregsdouglas

Tonto said:


> You can always change it back it it's horrible.


 True dat. Game on! If she gets mad at the look of it, I'll just show her the receipts for the cost of the equipment. She will stop caring about the look real quick and be mad about something else entirely.... 

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## sdurani

gregsdouglas said:


> Or are the left & right surrounds okay to be elevated like that?


All 4 of my surround speakers are between 6-7 feet off the floor, and I don't get the voice of god overhead effect.


gregsdouglas said:


> It is possible to use that 7" space and wall mount the Left & Rear surrounds just behind the seating area...


With a 7.1-speaker layout, you will already have a pair of surrounds "behind the seating area", so why put your other pair of surrounds there as well? I would put the other pair of surrounds directly to the sides of the seating area or even slightly forward of the seating area (for a bit more spaciousness). This will give you excellent rear-vs-side separation AND wrap-around envelopment in the surround field.


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## gregsdouglas

sdurani said:


> All 4 of my surround speakers are between 6-7 feet off the floor, and I don't get the voice of god overhead effect. With a 7.1-speaker layout, you will already have a pair of surrounds "behind the seating area", so why put your other pair of surrounds there as well? I would put the other pair of surrounds directly to the sides of the seating area or even slightly forward of the seating area (for a bit more spaciousness). This will give you excellent rear-vs-side separation AND wrap-around envelopment in the surround field.


I don't have anything directly behind me right now. Right now I have the typical LCR fronts, two height speakers at on the front wall at the top corners and I have the L&R Surrounds on the back walls at the corners.

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## sdurani

gregsdouglas said:


> I have the L&R Surrounds on the back walls at the corners.


Hence my suggesting not putting your other pair of surrounds "behind the seating area". There's already a pair back there. 

Dolby recommends placing the rear speakers between 60-90 degrees apart. You're roughly 7 feet from the back wall and your speakers are spread almost 14 feet apart. This makes their spread about 85 degrees, which is within the Dolby guidelines. If you want to bring them in closer together (no closer than 9 feet apart), that would make for an improvement but isn't critical. 

With sounds anchored behind you, the other pair of surrounds should be stabilizing imaging at your sides. Rather than blur the distinction between your side and rear speakers, a good 7.1 set-up will highlight the separation. Which is why I suggested placing them at your sides or just forward of the seating area.


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## gregsdouglas

sdurani said:


> Which is why I suggested placing them at your sides or just forward of the seating area.


Forward of the seating area? Would I still use the Surround Left & Right connections for that? Or the Front Wide then? I've never heard of or seen reference to the surrounds being a bit in front. Very interesting, thanks!

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## NBPk402

gregsdouglas said:


> Forward of the seating area? Would I still use the Surround Left & Right connections for that? Or the Front Wide then? I've never heard of or seen reference to the surrounds being a bit in front. Very interesting, thanks!
> 
> Sent from my iPhone using HTShack


Yes... I am running 9.1 and I have a pair behind me and a pair just forward of me. It is a standard setup for 9.1.


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## sdurani

gregsdouglas said:


> Forward of the seating area? Would I still use the Surround Left & Right connections for that? Or the Front Wide then?


Still use the surround connections. 

IF you were sticking to a 5.1 set-up with your surrounds in back corners of the room, then it helps to have wide speakers to bridge the wide gap between your main speakers in front of you and surround speakers behind you. 

But if you're doing a 7.1 set-up, with a pair of surrounds directly to your sides or slightly forward of the seating area, then the gap between the fronts and sides is much smaller, making wides less useful. 



gregsdouglas said:


> I've never heard of or seen reference to the surrounds being a bit in front.


Ever sit in the middle of a movie theatre? Notice that surrounds stretch well forward of your listening position. Famous audio researcher Floyd Toole always recommends placing surrounds forward of the listening position when doing a 7.1 set-up. 

http://www.cediaeducation.com/cgblog/4/15/The-Importance-of-Speaker-Placement-in-Home-Cinema-Design


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## gregsdouglas

Really wanted to thank you Sanjay for posting all the info. I took your advice and did the install this weekend. I put the new dual 4" CG24 monitors in at the left and right of the screen at head level when seated, with the center speaker (also CG24) just under the screen, very-slightly angled up to the head level. 

I moved my former L/R CG4 speakers to a spot approx 30" ahead of the seating area, toed-in towards the listening area. Those were connected to Surround Left and Surround Right. I then just moved the speaker wires for the formerly-Surround Left/Right channels onto the Surround Back Left/Right posts, leaving them mounted in the corners as I confirmed the angles were within the specs you referenced in your post. I left my old Polk Audio "Classic Series II" attached to the Front High Left/Right channels as they were already installed, the wires were run and I had the extra channels which can be turned on & off as needed. I really don't see that they add a lot to the overall sound stage though, so ultimately turned them off, thinking I'd be allowing for more power/overhead for the main speakers of the 7.2 rig, although just having them installed as 9.2 does kind of sound cool...

I was tempted to put the speakers on Surround Wide Left/Right instead of just Surround Left/Right but based on the diagram you linked, I think it was correct the way I wired it -can you confirm?

I then spent the entire weekend listening and re-listening to action movies (and a comedy my wife insisted upon.) I can't believe the difference the second sub makes and now with the Surround Left/Right speakers in front of me, with another set behind, there are some really cool effects I've never before noted at home. Early in War of the Worlds, as the storms are starting up, Tom Cruise notices the wind is blowing towards the storm and comments on it - they then show leaves swirling all around - THAT WAS AMAZING. It felt like I was actually in the yard watching and hearing the leaves around me. The most-realistic effect yet. 

On to the new GI Joe Retaliation. I had enjoyed that one before, but the way there are now distinctly different guns and explosions coming from ONLY a single surround speaker, and having them go through single speakers all around me again put me right into the action - and really, that's the point of all this. 

Very VERY happy with the new hardware and now that I've installed them "to spec" it's even better than before. 

....off to buy more Blu-rays! THANKS AGAIN!

-I tried to sketch out the area as now configured. Not sure it is legible, but I was never very good at drafting.

Basically two sofas, a door on the right to a guest bedroom, a door behind to a home office. The stairs leading up to the main floor are behind the seating area and to the right, and the area to the right of the seating area was a bedroom that was converted to a bar by blowing out that wall and making a raised bar that covers most of that wall, except for a 32" opening to walk in and out of the otherwise open area to the right. The BenQ W500 projector is pretty much directly over the main seating area, projecting onto a 100" 16:9 fixed-mount screen.


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## sdurani

gregsdouglas said:


> I was tempted to put the speakers on Surround Wide Left/Right instead of just Surround Left/Right but based on the diagram you linked, I think it was correct the way I wired it -can you confirm?


Confirmed. IF those speakers had been closer to your front speakers rather than slightly forward of your listening position, I would have used them as wides rather than surrounds. But at their current location, they're too far away from the fronts to be useful as wides.


gregsdouglas said:


> I can't believe the difference the second sub makes and now with the Surround Left/Right speakers in front of me, with another set behind, there are some really cool effects I've never before noted at home. Early in War of the Worlds, as the storms are starting up, Tom Cruise notices the wind is blowing towards the storm and comments on it - they then show leaves swirling all around - THAT WAS AMAZING. It felt like I was actually in the yard watching and hearing the leaves around me. The most-realistic effect yet.


There are a couple of things you'll discover about a good 7.1 set-up: 1) some of the best surround demo material you'll hear will be quiet scenes in movies rather than the typically loud demo material, and 2) you're going to start noticing phantom imaging between every pair of speakers (especially between the fronts and sides, where the wides would normally have gone). 

BTW, a couple of minor tweaks if you're willing: 

Since you can toe in your speakers, try pointing the fronts and sides at the person at the opposite end of the couch. This will make the nearby speaker less distracting for the person at either end of the sofa. 

Your diagram shows your subs co-located. Moving one of them to the opposite wall will make the bass smoother (fewer peaks & dips). 

Whether you do either tweak or both, remember to re-calibrate afterwards with Audyssey.


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## gregsdouglas

Thanks - yes. My plan was to have the subs in more of a stereo-position, straddling the center, but that will necessitate the moving of the AV shelf and removing ALL the wires due to the distances to the three power outlets and some short cords. In a couple weeks when my business slows down and I have more time. 

Adjusting toe-in on the surrounds is easy though!

Thanks again for all the help - much appreciated!

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## sdurani

gregsdouglas said:


> My plan was to have the subs in more of a stereo-position, straddling the center, but that will necessitate the moving of the AV shelf and removing ALL the wires due to the distances to the three power outlets and some short cords.


If you're going to go through all that trouble, I would strongly urge you to place the subs at ¼ room width in from the left & right walls. That will not only give you smoother bass response, but will do so across your entire seating area.


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## gregsdouglas

Unfortunately that may not be a good idea. Our sump pump sits in the left-front corner of the room, covered by a wooden box (covered by carpeting.) Placing left sub at 1/4 the room width would mean placing it on the box. Even though it is front firing and standing on metal spikes, I think the resonance may be a little much. 

I can place them at 1/3 and 2/3 though and have them on the carpet over the concrete floor. That was my basic plan.

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## sdurani

That will work, as long as they are symmetrically placed on either side of the centre line. Is there any space on the left side wall (e.g., opposite where the subs currently are)?


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## gregsdouglas

only at the very back, behind the seating area -which would mean a really long run of the sub's signal cable and the CAT5 Ethernet for the remote box for the sub's crossover and level controls. I'm thinking two at the front will do just fine for me. Cheers. :T


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## sdurani

Yeah, not worth the long run. Symmetrically up front will be fine.


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