# Need help with yet another basement conversion



## kjgarrison (Nov 17, 2007)

This first post is about overall design, and frankly, feasibility of doing the project at all.

Room is finished, basement, no windows. L,W,H is 22' x 16'10" x 7'8.5"

Plan is to do good sound isolation. Will use one of the reserved posts for this and another for acoustic and aesthetic room treatments. Looking at 9.2 speaker setup. Front projection. Acoustically transparent screen. As far as what products to buy goes, that's the subject of other reserved posts. Budget is relatively flexible within the range of "mid" price electronics. Hopefully a little less but maybe more. No set number yet.

Main design problem at this time has to do with placement of screen, speakers, and main viewing/listening positions.

I'm having problems with the layout needed for an acoustically transparent screen. I want to have the center speaker be the same as L & R mains, and I want excellent 2.1 listening.

Information I have come up with looking at various sites are as follows:
Recommended screen width "viewing angle" ~40 degrees with range of 35-45.
Recommended main listening position either 38% of room length from front wall or back wall. For my room this is either 8.4' or 13.6' from the front wall.
Recommended speakers angle from man listening position of 45 degrees for THX or 60 degrees for Dolby.

From what I have read having the main viewing/listening position close to the front wall/screen (at 38%) is preferable, acoustically speaking, to having it at the 62% point. I do not know how much breathing room to leave between the center speaker and the wall behind it and between the center speaker and the screen. Almost no matter how small of a gap this requires between the screen and the front wall, I end up with a smallish screen that I have to sit (it seems to me) too close to. Even if the screen were on the wall, the distance is 8.36', and if the center speaker needs 2' I'm only going to be a little over 6' from the screen. Using 40 degree screen width, this means the screen would only be ~55" wide.

I can move back to the 68% location, have 3' behind the screen and wall, have 3' between the L&R mains and the side walls and almost 4.5 feet out from the front wall, and still have around a 90" screen. This is using the 60 degree Dolby recommendation. Using the 45 degree THX recommendation gives me a lot more flexibility. I need guidance with the THX vs Dolby R&L mains angle issue. I'm thinking the THX is more of a cinema number and Dolby more musically oriented. Since I want to have excellent music listening, perhaps I should favor Dolby's 60 degree recommendation. Still I hope *somebody can say how much of a compromise each standard represents* for the other purpose. 

So to refine this, I need to know *how much space is needed in front of (speaker-to-screen) and behind (speaker-to-wall) the center speaker*. I assume it *depends on the center speaker, and I could use some help with this*. I as looking at Martin Logans thinking they would be better given my low ceiling issue due to their directivity character. These speakers need perhaps more space beside and behind. *Thoughts?*

(PS: I have spent hours looking for these answers on my own without finding any convincing or consistent answers.)


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## kjgarrison (Nov 17, 2007)

Sound Isolation


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## kjgarrison (Nov 17, 2007)

Projector and Screen

AT Screens Recommended:

Center Stage XD


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## kjgarrison (Nov 17, 2007)

Speakers, Audio Equipment, and Acoustic treatments

Recommendations:

Front wall absorption, whole wall. (Said to allow for speaker to be closer to wall.)


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## kjgarrison (Nov 17, 2007)

Esthetics, aka WAF


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## kjgarrison (Nov 17, 2007)

reserved 5


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## patchesj (Jun 17, 2009)

I used Center Stage XD screen material and LOVE it. Since you'll be using a false wall (assumed this with an AT screen...), cover the entire front wall with absorbtion material. This will help you a bit with placing speakers closer to the front wall and not requiring the screen to be so far into the room. Everything is a compromise and you'll never be able to hit Dolby, THX, and 2 channel recommended specs. I have a viewing angle and speaker angle close to 45 degrees from my front row, speakers just inside the AT screen edge. It works great for movies and 2 channel music. You don't want your speakers too close to the side walls either.


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## kjgarrison (Nov 17, 2007)

patchesj said:


> I used Center Stage XD screen material and LOVE it. Since you'll be using a false wall (assumed this with an AT screen...), cover the entire front wall with absorbtion material. This will help you a bit with placing speakers closer to the front wall and not requiring the screen to be so far into the room. Everything is a compromise and you'll never be able to hit Dolby, THX, and 2 channel recommended specs. I have a viewing angle and speaker angle close to 45 degrees from my front row, speakers just inside the AT screen edge. It works great for movies and 2 channel music. You don't want your speakers too close to the side walls either.


Thanks for the ideas. Truthfully, I have seen "false wall" mentioned but never thought of what one is or why I would want it. I'll do some research. Apparently this doesn't cause an additional hollow space to mess acoustics up.

Anybody else use Center Stage XD or have a reason to use something else?

As to the front wall absorption material, I read that THX recommends 1" Insul-Shield. Link below. I'm not sure whether to use the "faced" or "non-faced" version. 
http://www.specjm.com/products/insulationboards/insulshieldfaced.asp

Even though this is part of the acoustic treatment section, it does impact design, and I still need to know how much space to leave behind the screen for the center speaker- or at least a ballpark idea. At this point in my design sketches, I have 3' between R&L mains and side walls and 3' or more behind the R&L mains and front wall (depending on whether I put R&L straight with the screen or equidistant with the center speaker from viewing/listening position.


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## patchesj (Jun 17, 2009)

I used 2" rockboard across my front wall, and then an additional 6" in the corners for low end absorbtion. You also need to be careful placing the speakers too close to the screen, you'll get reflections and filtering issues. I actually found that mine sounded best closer to the wall with more room to the screen side.


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## Prof. (Oct 20, 2006)

I have an 8' 6" wide..Center Stage XD Scope screen, mounted in a screenwall that is 2' 6" out from the front wall..
I needed the screen wall that far from the front wall to accommodate both the sub and a baffle wall that the front speakers are mounted in ..
You may not go to the extent of a baffle wall, but If you're planning on placing the sub behind the screen as well, then that will most likely determine how far out the screen wall will need to be..


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## kjgarrison (Nov 17, 2007)

patchesj said:


> I used 2" rockboard across my front wall, and then an additional 6" in the corners for low end absorbtion. You also need to be careful placing the speakers too close to the screen, you'll get reflections and filtering issues. I actually found that mine sounded best closer to the wall with more room to the screen side.


Thanks, patchesj. So how much clearance did you end up with between your speakers and your screen?


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## kjgarrison (Nov 17, 2007)

Prof. said:


> I have an 8' 6" wide..Center Stage XD Scope screen, mounted in a screenwall that is 2' 6" out from the front wall..
> I needed the screen wall that far from the front wall to accommodate both the sub and a baffle wall that the front speakers are mounted in ..
> You may not go to the extent of a baffle wall, but If you're planning on placing the sub behind the screen as well, then that will most likely determine how far out the screen wall will need to be..


Thanks. I'm hoping and planning to only have the center speaker behind the screen.

So how far is the screen in front of your center speaker? Your distance of 2.5' includes the depth of the speaker, the space between front wall and speaker, and the space between speaker and screen, right? Unless, I guess that you have in-wall or on-wall speakers.

I really need to find out more about screenwalls or false wall. Google is my friend.


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## Prof. (Oct 20, 2006)

kjgarrison said:


> Thanks. I'm hoping and planning to only have the center speaker behind the screen.
> 
> So how far is the screen in front of your center speaker? Your distance of 2.5' includes the depth of the speaker, the space between front wall and speaker, and the space between speaker and screen, right?


Correct..
If you do a search on Google images..You'll find a photo of my baffle wall and how the speakers are mounted.. The link on the image is Home Theater Shack.. The baffle wall is between the front wall and the screen wall..with the front of the centre speaker mounted about 15" from the screen..and patchesj is correct..It's better to have the speakers back close to the front wall..


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## kjgarrison (Nov 17, 2007)

Prof. said:


> Correct..
> If you do a search on Google images..You'll find a photo of my baffle wall and how the speakers are mounted.. The link on the image is Home Theater Shack.. The baffle wall is between the front wall and the screen wall..with the front of the centre speaker mounted about 15" from the screen..and patchesj is correct..It's better to have the speakers back close to the front wall..


OK, I'm back from Googleland with new understanding of the screen wall as well as a new plan to put all speakers behind it. Simple. I will have 3' behind it.

and now ...

aaaaack! A new term: Baffle wall ... and a return to Google. Found the pics and the main idea of the what but not so much the why. I'm a little fuzzy as to why do it. I mean what about the BSC (baffle step compensation) built into the speakers' crossovers? Why not just do in-wall speakers? After all they don't have BSC and you don't have to build a 3rd wall. Also, doesn't the baffle wall have sound reflection problems and doesn't it prevent sound from getting to all the absorption called for on the front wall?

I'll look at it more when I have time. Right now, it's nite-nite.

Thanks for your guidance, Prof.


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## patchesj (Jun 17, 2009)

I would research the baffle wall as well. I've thought about experimenting with one, but I've had such good results with the the current setup it is difficult to justify the additional work. I have probably a foot for my center channel to the rear of the screen, 6-8" for the mains (they are toed in). My build is here on the forums somewhere, I don't have the link handy.


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## Prof. (Oct 20, 2006)

kjgarrison said:


> aaaaack! A new term: Baffle wall ... and a return to Google. Found the pics and the main idea of the what but not so much the why. I'm a little fuzzy as to why do it. I mean what about the BSC (baffle step compensation) built into the speakers' crossovers? Why not just do in-wall speakers? After all they don't have BSC and you don't have to build a 3rd wall. Also, doesn't the baffle wall have sound reflection problems and doesn't it prevent sound from getting to all the absorption called for on the front wall?


Firstly..most cinema complex's use baffle walls and it is a proven standard in the industry..The speakers are specifically designed to be placed in a baffle wall..and the wall itself extends from floor to ceiling and wall to wall..Consequently, not all home theatre speakers are suitable for mounting in a baffle wall..

The advantage of the baffle wall is that the front wave and rear wave of the speakers are completely isolated from each other...the improvement in the quality of the sound is obvious.. 

The greatest benefit derived from this type of set up is pin point accurate sound across the whole screen..with no blurring or blending of the sound between speakers..
Also the tonal quality across the screen remains more constant..

It is a lot of extra work (and cost) to build a baffle wall, but well worth it..


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## kjgarrison (Nov 17, 2007)

With regards to baffle walls, here is a thread with a lot of insight. The posts by Dennis Erskine are particularly informative.
http://www.avsforum.com/avs-vb/showthread.php?t=1280395

There are a lot of different things written about baffle walls, some of which either are confusing or just don't make sense.

Here are a few with a comment of mine for some:

Baffle walls are compared to infinite baffle. Well I have actually built an IB subwoofer, and I have a hard time seening how IB speakers would work in HT without one of two conditions being met. The back side of the IB would either have to be vented to the outdoors, or if vented to a large space indoors, that space would have to have sound isolation. Basically this space needs to be another room.
Some, such as THX, say the baffle wall needs to be wall to wall and floor to ceiling. Others say not necessarily.
I saw a THX recommendation to leave 12" between the baffle wall and the screen. So if you follow this and THX other recommendation to have the baffle wall floor-to-ceiling/wall-to-wall, where do the front wall bass traps go?

It seems to me that the only speakers that would work are in-wall designs, which have no BSC. Unless, that is, you include some of the DIY projects where BSC can be left out, or you plan to open up speakers and modify the crossover. Then Dennis Erskine talks about the need to know the polar radiation of speakers to know how to design the baffle wall. I didn't see any mention of whether the in-wall speakers should have boxes, but I assume they should/would.

I couldn't find anything about what to do with the space behind the baffle wall and the actual front room wall, such as whether to stuff it with insulation, coat it with insulation, or seal off the baffle wall from it.

Just an interim report of what little I have learned so far over the past couple of days. Adding this to what I've learned with some other attempts on my part to trust my own DIY design skills, I'm increasingly inclined to get professional help.


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## Prof. (Oct 20, 2006)

Yes..you're right..There is a lot of confusing and contradictory statements about baffle walls..and to confuse things even further, even Dennis Erskine has built baffle walls that don't comply with his own statements!!
He and THX say that only one special type and thickness of acoustic insulation can be used on the face of baffle walls..and yet I've seen photos where he has just put 2" thick yellow fibreglass (probably OC705) on the face..

Having the baffle wall floor to ceiling and wall to wall is another area of confusion..Some installation have that and others just have enough area to cover the screen size..People have said that the latter has worked fine for them, which I can vouch for as my baffle wall is the same..and works very well..
Also my baffle wall was just covered with a black car carpet material (rubber backed) and this does a good job..



> Baffle walls are compared to infinite baffle. Well I have actually built an IB subwoofer, and I have a hard time seening how IB speakers would work in HT without one of two conditions being met. The back side of the IB would either have to be vented to the outdoors, or if vented to a large space indoors, that space would have to have sound isolation. Basically this space needs to be another room.


Baffle walls bare no resemblance to IB's, other than there is a space behind the speakers..
With an IB you're mounting the drivers directly onto the baffle..with free space behind..

The baffle wall has your speaker cabinets mounted in cutouts in the wall and basically increases the size of the individual speakers baffles..The space behind the speakers is not critical other than to control and reduce any back wave and resonances..



> I saw a THX recommendation to leave 12" between the baffle wall and the screen. So if you follow this and THX other recommendation to have the baffle wall floor-to-ceiling/wall-to-wall, where do the front wall bass traps go?


Providing you have enough depth between your front wall and the baffle wall, then the bass traps would still be placed in the front wall corners..




> It seems to me that the only speakers that would work are in-wall designs,


In-walls are designed to be used in restricted spaces..as in mounting in walls..They are not designed nor suitable to be used in baffle walls..




> Then Dennis Erskine talks about the need to know the polar radiation of speakers to know how to design the baffle wall.


Yes I read that also and I think he is referring to the angling and tilt of the baffle wall..Some baffle walls are flat across the screen,horizontally and vertically, whilst others use a curved wall or individual angled panels to accommodate toe in..and some require the wall to be tilted down..It all depends on the speakers being used..



> I couldn't find anything about what to do with the space behind the baffle wall and the actual front room wall, such as whether to stuff it with insulation, coat it with insulation, or seal off the baffle wall from it.


No special requirements are needed here other than to cover your entire front wall with the normal 2" thick insulation..

If you are in a position to use a professional to design your baffle wall, then that would be the best way to go..Otherwise it can be a bit of a hit and miss ..


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## kjgarrison (Nov 17, 2007)

Prof. said:


> Yes..you're right..There is a lot of confusing and contradictory statements about baffle walls..and to confuse things even further, even Dennis Erskine has built baffle walls that don't comply with his own statements!!
> He and THX say that only one special type and thickness of acoustic insulation can be used on the face of baffle walls..and yet I've seen photos where he has just put 2" thick yellow fibreglass (probably OC705) on the face..


I know THX say to just use one acoustic treatment of the baffle wall, but I saw a post of DE where he said the polar radiation of the speaker needs to be known to choose the right treatment. I think the THX recommended product is only 1" thick; InsulShield or something like that. From other posts of DE, I'm sure he had the yellow OC705 covered with black speaker screen.




Prof. said:


> Having the baffle wall floor to ceiling and wall to wall is another area of confusion..Some installation have that and others just have enough area to cover the screen size..People have said that the latter has worked fine for them, which I can vouch for as my baffle wall is the same..and works very well..
> Also my baffle wall was just covered with a black car carpet material (rubber backed) and this does a good job..


Yes I see so many posts and builds as in your case and others, where less than wtw/ftc is done. However, I also saw the THX recommendation and it is clear: wtw/ftc. Period. [EDIT:] But then what about the big hollow space between this complete wall and the front wall of the room???? Isn't the absorption material on the *front* of the baffle wall there to deal with reflected sound off the back of the screen? What is done with this new hollow space in these "proper" THX setups?

I am curious and please take no offense here, how you have concluded that your baffle wall "works very well". Were measurements involved, or are you just going by "ear"? (which might be better than measurements if you have audiophile ears ..)




Prof. said:


> The baffle wall has your speaker cabinets mounted in cutouts in the wall and basically increases the size of the individual speakers baffles..The space behind the speakers is not critical other than to control and reduce any back wave and resonances..
> 
> In-walls are designed to be used in restricted spaces..as in mounting in walls..They are not designed nor suitable to be used in baffle walls..


This brings up the whole "why" for me with regards to the baffle wall in the first place. I mean why not use the wall that is already there (the front wall of the room)? I can only conclude that this would compromise sound isolation by making pretty big holes in the room within a room concept.

The statement that in-walls are not designed nor suitable to be used in baffle walls baffles me (pun intended). Yes, in-walls are for mounting in walls. Isn't this thing called a baffle wall? And don't you try to duplicate what an in-wall speaker does with the hole you cut for your speaker to fit snugly into? Then you have to find a way to support your speakers to the right height, right? Then seal the gap, I presume.

In-walls come with templates to cut the hole the size you need at the height you need it.

Then there is the baffle step compensation (BSC) that all speakers, except in-walls and DIY projects, have. These speakers in this big baffle wall need no BSC.

Good quality in-walls are THX certified and also come with enclosures. Now here is where I get a little dubious of what I am saying ... Yes, they have "enclosures" but do these approach the stiffness of the boxes your regular speakers have? I'm thinking "no" .. but then there's still the BSC that your regular speakers have ...

The THX pictures of the baffle walls look like those are boxy in-wall speakers to me!




Prof. said:


> If you are in a position to use a professional to design your baffle wall, then that would be the best way to go..Otherwise it can be a bit of a hit and miss ..


Do you have a name, or names, to recommend? If you don't want to post it, you can PM me. I'm thinking I'll go with the professional design of the whole theater, and then research any recommendations or specifications that seem odd. Then I'll sub out some of the basic contractor stuff, like framing, drywall hanging, carpet laying, and electrical wiring. I have some contacts in the building trades that I trust. The rest will be DIY.

Meantime I'm going to dig into this baffle wall concept until I can discuss it somewhat intelligently with whomever it is that designs this theater for me.

And thank you so much with your help, Prof.!! :T


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## fitzwaddle (Aug 25, 2010)

I'm also using a Seymour CenterStage XD screen, 136" wide, my front row is about 12' from the screen; screen mounted on a false wall, which is 2' from the front wall. My room is 23'x17'x9'. My L/R speakers are about 12" inboard from the sides of the screen. I started with all the angles as a starting point, then kind of tossed them and let my eyes and ears be the guide and it has worked out very well. Very happy with the screen and sound.


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## Prof. (Oct 20, 2006)

> But then what about the big hollow space between this complete wall and the front wall of the room???? Isn't the absorption material on the *front* of the baffle wall there to deal with reflected sound off the back of the screen? What is done with this new hollow space in these "proper" THX setups?


If you're referring to the space between the baffle wall and the screen, then the only treatment is the insulation on the face of the wall.
The space between the baffle wall and the front wall is just the 2" of insulation on the front wall..for a home theatre..
I have seen photos of commercial theatre installations where there isn't any insulation behind the baffle wall, but in those situations, there is usually a huge distance between the baffle wall and the front wall of the theatre..




> I am curious and please take no offense here, how you have concluded that your baffle wall "works very well". Were measurements involved, or are you just going by "ear"? (which might be better than measurements if you have audiophile ears ..)


I'm of the old school.. lddude: where I do most of my audio calibrations by ear..I'll use the receivers EQ system initially and then make minor adjustments to the individual frequencies, that is to my liking!.
In evaluating the improvements with the baffle wall, I played a Blu-ray movie that I know very well..having watched it numerous times..

The first thing that struck me was how I was able to pin point the sound at any position on the screen..and secondly, how much cleaner the sound was overall..with no blurring of voices..
The other was how much the sound extended past the screen on each side, so that you could easily follow a vehicle coming into the picture from off screen to the left..passing across the screen..and out the other side..
A good example of that was the opening scenes in War of the Worlds, where the trucks are coming into the picture from the right and passing out the other side..That was much better detailed after the baffle wall was installed..



> This brings up the whole "why" for me with regards to the baffle wall in the first place. I mean why not use the wall that is already there (the front wall of the room)? I can only conclude that this would compromise sound isolation by making pretty big holes in the room within a room concept.


I guess you could use the front wall as a baffle wall...providing you don't mind the back of your speakers sticking outside in the elements! 
If the front wall of your theatre was a wall within the house, then it probably could be used as a baffle wall..and if the in-wall speakers have backs, then I guess they could be used successfully..



> The statement that in-walls are not designed nor suitable to be used in baffle walls baffles me (pun intended). Yes, in-walls are for mounting in walls. Isn't this thing called a baffle wall? And don't you try to duplicate what an in-wall speaker does with the hole you cut for your speaker to fit snugly into? Then you have to find a way to support your speakers to the right height, right? Then seal the gap, I presume.


My only concern here would be that the sound quality of in-walls would not be the same as large freestanding speakers..I don't know of any in-walls that have been compared to being the equivalent of a quality free stander!..but then I could be wrong..



> Then there is the baffle step compensation (BSC) that all speakers, except in-walls and DIY projects, have. These speakers in this big baffle wall need no BSC.


I don't know that ALL speakers have BSC incorporated in them..Looking at the specs of my speakers, there is no mention of BSC!



> Do you have a name, or names, to recommend? If you don't want to post it, you can PM me. I'm thinking I'll go with the professional design of the whole theater, and then research any recommendations or specifications that seem odd. Then I'll sub out some of the basic contractor stuff, like framing, drywall hanging, carpet laying, and electrical wiring. I have some contacts in the building trades that I trust. The rest will be DIY.


Being on the other side of the world, I can't give you any recommendations..
My only contact? in Wisconsin is the University..where I use their daily World Cyclone charts they put up on the internet! :bigsmile:

I hope I have been able to help you in some way..


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## Prof. (Oct 20, 2006)

fitzwaddle said:


> I'm also using a Seymour CenterStage XD screen, 136" wide, my front row is about 12' from the screen; screen mounted on a false wall, which is 2' from the front wall. My room is 23'x17'x9'. My L/R speakers are about 12" inboard from the sides of the screen. I started with all the angles as a starting point, then kind of tossed them and let my eyes and ears be the guide and it has worked out very well. Very happy with the screen and sound.


Brad..are you using a baffle wall or plan to put one in?

Strike that!..I've just seen your latest photos and you don't have a baffle wall! :R


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## fitzwaddle (Aug 25, 2010)

Prof. said:


> Brad..are you using a baffle wall or plan to put one in?
> 
> Strike that!..I've just seen your latest photos and you don't have a baffle wall! :R


Hey Prof, don't go planting seeds in my head like that - you know how easily we are nudged into envy mode! :dumbcrazy:

I'd never say never though - I don't believe I've ever experienced a baffle setup (well other than at a non-residential theater no doubt) to know what I'm missing.


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## Prof. (Oct 20, 2006)

:rofl: I followed Mark's (CAVX) build and was so impressed by his results that I decided to build one myself..and since I'm trying to replicate a commercial theatre in my own room..it seemed like the way to go..
I'm glad I did!..It's now getting close to real thing!!


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## kjgarrison (Nov 17, 2007)

Thanks Prof and Brad. Sounds like that Centerstage XD is a winner.

It gets even more muddled. I have found a second THX description of a baffle wall that says the wall should at least be as big as the screen. Another official looking at least THX document I found said wall-to-wall/floor-to-ceiling.

Perhaps this isn't so much different if you consider how big cinema screens are, and maybe they were talking about the recess in which cinema screens sit ... just a thought.

I'm going to keep looking for answers, because having the baffle wall be screen size or any size for that matter that isn't the whole width and height of the room, greatly simplifies the build, leaves some nice spaces all around for bass absorption, and makes room for subwoofer placement, etc. (You don't include the subs in this baffle to you?)

I'm hoping this is the preferred size, and from what you guys have said, it seems to be much better than having freestanding speakers behind the screen, even with the whole front wall behind them fully treated with absorption.

Prof. what kind of speakers to you have? I'm no expert, but if they have a baffle they most likely have BSC built into their crossover.

Another thought. I've seen mention of toeing in the R&L mains, and with the baffle wall angling the R&L segments to accomplish the same thing. I'm wondering if this roughly 22 degree angle of incidence of these speakers hitting the AT has any effect on screen penetration or reflection (as in less penetration and more reflection). I also wonder if angling the R&L wings has any effect on the relationship of the other (center) baffle, now becoming 3 baffles. The pictures I've seen of THX all look pretty much straight, as in without any toeing in ...


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## Prof. (Oct 20, 2006)

kjgarrison said:


> It gets even more muddled. I have found a second THX description of a baffle wall that says the wall should at least be as big as the screen. Another official looking at least THX document I found said wall-to-wall/floor-to-ceiling.
> 
> Perhaps this isn't so much different if you consider how big cinema screens are, and maybe they were talking about the recess in which cinema screens sit ... just a thought.


That's probably right..considering that cinema screens are nearly wall to wall.. Obviously they would make the baffle wall the same..so if your in-home installation is similar, then you would make it wall to wall..
My screen is almost wall to wall so my baffle wall is almost the same..




> I'm going to keep looking for answers, because having the baffle wall be screen size or any size for that matter that isn't the whole width and height of the room, greatly simplifies the build, leaves some nice spaces all around for bass absorption, and makes room for subwoofer placement, etc. (You don't include the subs in this baffle to you?)


My baffle wall only extends down to the top of the sub..This allows me to move the sub slightly to find the best position..



> Prof. what kind of speakers to you have? I'm no expert, but if they have a baffle they most likely have BSC built into their crossover.


I'm using Behringer Monitors (3 identical speakers) across the front..Looking at the specs for those speakers, there is no mention of BSC, so I don't know if it's included or not! :scratch: Usually speaker makers will include all sorts of details, just to make their speakers seem like the best..so I would have thought that they would mention that..



> Another thought. I've seen mention of toeing in the R&L mains, and with the baffle wall angling the R&L segments to accomplish the same thing. I'm wondering if this roughly 22 degree angle of incidence of these speakers hitting the AT has any effect on screen penetration or reflection (as in less penetration and more reflection). I also wonder if angling the R&L wings has any effect on the relationship of the other (center) baffle, now becoming 3 baffles. The pictures I've seen of THX all look pretty much straight, as in without any toeing in ...


My speakers were toed in before I had the baffle wall, so I made the wall to achieve the same angle for the L&R..

Some of the cinema walls are curved and others are made flat..Why the difference.. I don't know..
Sound penetration through the AT screen with toe in may be attenuated to a minor degree..but that can be adjusted with a slight increase in level to balance all 3 fronts..With all 3 balanced at 75dB. I can't tell any difference between then except for a slight tonal change of the L&R to the centre speaker...but barely noticeable..


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## kjgarrison (Nov 17, 2007)

Thanks Prof.

I found some off angle testing, and it appears that even up to as much as 40 degrees has little to no effect. Good to hear, and this corresponds to your observations.

I'm hoping to find a HT setup with a baffle wall to THX specs someplace in the upper midwest to listen to ... I'm really interested.


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## fitzwaddle (Aug 25, 2010)

kjgarrison said:


> Thanks Prof.
> 
> I found some off angle testing, and it appears that even up to as much as 40 degrees has little to no effect. Good to hear, and this corresponds to your observations.


Chris Seymour did some testing and posted the results in the AVS Seymour thread, and yeah, the impact of toe-in was really negligible - can't find that post at the moment though.


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## patchesj (Jun 17, 2009)

I would think that a slight angle would be beneficial, perhaps reducing the amount of backside reflection bouncing back to the speaker baffles/drivers? The XD screen really is impressive, I think you'll like it a lot.


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## kjgarrison (Nov 17, 2007)

fitzwaddle said:


> Chris Seymour did some testing and posted the results in the AVS Seymour thread, and yeah, the impact of toe-in was really negligible - can't find that post at the moment though.


Yes, that's the one I found.


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## Prof. (Oct 20, 2006)

When I did my screen, Chris sent me a sample of the XD and 4K materials..
Even though the 4K is supposed to be a better quality with even finer holes than the XD, I personally found the XD produced a brighter image!..
One concern was the minimum recommended viewing distance for the XD, but I sit 9'6" from an 8'6" wide screen and I don't seen any weave in the screen material..


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## patchesj (Jun 17, 2009)

Prof. said:


> When I did my screen, Chris sent me a sample of the XD and 4K materials..
> Even though the 4K is supposed to be a better quality with even finer holes than the XD, I personally found the XD produced a brighter image!..
> One concern was the minimum recommended viewing distance for the XD, but I sit 9'6" from an 8'6" wide screen and I don't seen any weave in the screen material..


My front row is slightly closer than that and I can't see the weave. I had Chris cut my material on a bias and that should help a bit as well. I don't think you can go wrong with the XD stuff. I'm sure Chris will send some samples.


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## kjgarrison (Nov 17, 2007)

Thanks guys. I'm holding off on as much of the technology for as late in the project as possible. Never know what will be out there in a year (or two).


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