# Need Advice on Treating This HT/Music Room



## cyniclaus (Mar 25, 2010)

Hi all! I truly appreciate any advice in this situation! :help:

I just purchased a home a couple of months ago and I am stuck with a less than ideal space for my home theater room. The room is only 10' wide and yet 20' long with 8' ceilings. I can't put bass traps in the back two corners because there are doors there, and the front two corners are consumed by my 132" projector screen that only leaves a couple inches of clearance on either side! The worst thing is, the front of the room (behind the screen) is a bay window and the glass rattles like crazy from the sub. :sad:

The walls and ceiling are drywall and the floor is concrete, carpeted with a 1/2-inch pad. 

My idea: Use 2' x 4' 2-inch commercial acoustic panels on the walls (5 per side), and maybe some thicker panels on the rear wall. I would then seal off the bay window with plywood, filling the cavity with insulation to create a giant bass trap. Even though it's unlikely to tame the bass in the room all by itself, it would theoretically at least stop the windows from rattling. :scratchchin:

I hope you like my diagram... it took me more time than I'd care to admit to make it with all the distances to scale :nerd:










I also have 4 GIK tri-traps left over from my last room and since I can't put them in the traditional corners, I was debating whether it would be worth hanging them in the side "corners" where the ceiling meets the wall. :huh: Not sure if I will treat the ceiling; there are a series of can lights that would make it tricky, but maybe some diffusing foam at the primary reflection points.

I love my equipment, but it is really ill suited to the room. :doh: I should only be living here for 3 years, so it's not worth swapping out. I just need to make the most of a bad situation and hopefully still be able to enjoy my movies and--more importantly--all my multichannel audio and blu-ray music.

Audio Equipment:
Mains: MartinLogan Vantage
Center: MartinLogan Motif
Surround: MartinLogan Script (wall mounted)
Rear Surround: None currently
Sub: Seaton Submersive HP
Amp: Onkyo TX-SR805
Source: Oppo BDP-93 with HDD

Right now in the untreated space the sound is very unbalanced in general, and the Submersive completely owns the room. It's actually quite ridiculous (and not in a good way)


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## Andre (Feb 15, 2010)

Get ahold of Mr Pape at GK Aoustics 

http://gikacoustics.com/


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## bpape (Sep 14, 2006)

You can certainly use the bass control in the wall/ceiling junctions as long as you do it as symmetrically as possible on the 2 sides of the room.

It's unfortunate that the screen is so oversized for a room of those dimensions. 


Whatever area of the front wall that isn't covered by the screen should have 2" of 703 or similar covered with black fabric to help minimize reflections from the surround channels.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> It's unfortunate that the screen is so oversized for a room of those dimensions.


Thanks; I am giving strong consideration to getting a smaller screen. Aside from the acoustic issues it causes, this screen has less than 3" clearance from the walls, which causes distracting light reflection. The problem is, the smaller the screen the closer I need to sit, and then I need to push my MLs closer to the wall which is bad, but maybe the lesser of sonic sins in this case

But what about my biggest problem - the bay window? Is my idea to seal it off sound? Plywood with some kind of insulation rolls stacked floor to ceiling behind it?


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## bpape (Sep 14, 2006)

At 20' long, acoustically you'd like to sit just less than 8' from the wall behind you. A smaller screen should not present any problems at that viewing distance. THX min recommended included viewing angle is 36 degrees. Also the speakers would not move front to back as they're tied to your seating location and if anything, you'd get more breathing room to the sides.

Bryan


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## cyniclaus (Mar 25, 2010)

OK, so you really got me thinking about the screen size and I came up with an idea... I think I will get a fixed frame 96" screen (80" wide), mount it on a custom easel, place it 3ft forward of the wall, bringing the main speakers and center up on line. This ameliorates several problems:

1) makes room for the tri-traps to be stacked in the front corners
2) creates space behind the main speakers
3) stops the mains from reflecting off the screen
4) keeps the image the same (perceived) size since the screen is closer to the seats
5) lets me put my massive subwoofer behind the screen where it is hidden and saves space

Here is the revised diagram; please let me know what you think :T:









...I still don't see a solution to treating the rear corners since they both are adjoined by a pair of doors, And I still need advice on the bay window bass trap... hopefully someone has experience or even theoretical knowledge on this :scratchchin:


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## bpape (Sep 14, 2006)

I wouldn't sweat the rear corners as much as the center of the rear wall.

As for the front, that's certainly doable. You could also just build a false wall and cover with Guilford fabric and accomplish the same thing with a cleaner look.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> I wouldn't sweat the rear corners as much as the center of the rear wall.
> 
> As for the front, that's certainly doable. You could also just build a false wall and cover with Guilford fabric and accomplish the same thing with a cleaner look.
> 
> Bryan


Thanks, so do you think the idea of putting some 244s up on the back wall will be sufficient broadband absorption?

What sound deadening material would you recommend I put in the bay window area, and how much? I'm thinking it doesn't have to be pretty since it will be hidden "behind the curtain". In fact, a light-blocking black curtain may not be a bad idea (instead of plywood) since it is only for a couple of years.


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## bpape (Sep 14, 2006)

Monsters would be better on the rear but 244's will work.

Front wall should be 100% dead at least 2" thick.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> Front wall should be 100% dead at least 2" thick.


Thanks - 

So you are saying a wall of rigid fiberglass only 2" thick would be enough? I was thinking it would take a lot more depth than that!



bpape said:


> Monsters would be better on the rear but 244's will work.


Hmm, well I would go with the monsters, but not sure if I can deal with over 7 inches protruding from the wall in a traffic area. Here is are pictures of my room so you can see (tape outline) where I was thinking to put the rear panels. Couch and tables are temporary pending arrival of my row of 3 theater seats. The tri-traps will be stacked to the ceiling in the front, but I need to take down the wall mounted motorized screen first:


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## bpape (Sep 14, 2006)

2" is the full wall coverage. You'll need more but just in the corners.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> 2" is the full wall coverage. You'll need more but just in the corners.
> 
> Bryan


OK, thanks, that shouldn't be too difficult.

Do you think my panel placement on the rear wall (as taped off in the picture) will work well?


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## bpape (Sep 14, 2006)

Looks pretty good though pending the speakers being in position in the drawing, I'd say you don't need the front most 2 and likely not the rear most 2 - probably 3 per side would do it.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> Looks pretty good though pending the speakers being in position in the drawing, I'd say you don't need the front most 2 and likely not the rear most 2 - probably 3 per side would do it.
> 
> Bryan


Thanks - I'm glad you brought that up... I am frustrated and confused about what to do about the rear of these speakers. The MartinLogans being electrostats/dipoles, they are supposed to be spaced way off the walls and I just can't accomplish that in this room. I am still not sure if the best thing to put behind them is A) nothing B) absorption C) diffusion. It probably matters less now since they will likely reflect onto the back of the screen, but then again that could be worse. :scratch: 

At least the surrounds, although they are still dipoles, were designed to be wall mounted.


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## bpape (Sep 14, 2006)

I prefer to normally use diffusion behind electrostats, Magnepans, etc - any panel or OB type speaker. In home theater though we really want to kill the front wall and that's an acceptable thing behind them also. The point is to address the rear wave to prevent comb filtering.


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## cyniclaus (Mar 25, 2010)

bpape said:


> I prefer to normally use diffusion behind electrostats, Magnepans, etc - any panel or OB type speaker. In home theater though we really want to kill the front wall and that's an acceptable thing behind them also. The point is to address the rear wave to prevent comb filtering.


So are you saying to just leave the side walls behind the speakers bare since, with the speakers toed in, any reflections are going to bounce from the side walls onto the deadened front wall? Or should I put a diffusor or absorption panel on the side wall behind the mains?


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## bpape (Sep 14, 2006)

My bad, the ones behind the speakers on the side wall would be needed if the corner traps don't catch most of it.

Bryan


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## cyniclaus (Mar 25, 2010)

OK, so as I get ready to order my panels let me make sure I am straight on what I need, working from front to back:

Front Wall: 4x GIK Tri-Traps in corners (already have them) and a blanket-like curtain covering the bay window cavity that will be stacked to the ceiling with fiberglass insulation rolls

Side wall behind the mains - 242 panels?

Side wall in front of mains - 242 panels at primary reflection points

Side wall in front of surround speakers - 242 panels at primary reflection points

Side wall to the rear of the surround speakers - ??? I left just enough room for 242 panels or diffusors

Rear wall - 2 x monster traps or possibly 244s

Ceiling - nothing because MartinLogans don't project sound upwards. However, if the above setup doesn't tame the bass in the room, I could possibly hang monster traps on the ceiling where it meets the back wall if that would help.


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## bpape (Sep 14, 2006)

242's behind the rear surrounds likely not needed.

You still have refelctions on the ceiling - just not higher frequencies as they beam in the vertical dimension. I would wait on those til you get the rest done and see if you want/need them.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> 242's behind the rear surrounds likely not needed.
> 
> You still have refelctions on the ceiling - just not higher frequencies as they beam in the vertical dimension. I would wait on those til you get the rest done and see if you want/need them.


OK, thanks -- I'll do that. 

A couple of last concerns... you mentioned that 8ft from the rear wall is the best place for my listening position, and that is where I am going to place it, but is there any rule about where to place my mains or will they work where I have them (3ft from the front wall)? What about the sub? Ideally I would keep it behind the screen, but I could also put it right behind the seats or butted up against the rear wall.


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## bpape (Sep 14, 2006)

Put the sub wherever you get the smoothest response - preferably up front. Speakers need to be set up to balance screen lock, imaging, frequency response, etc. With panels, it's just a lot of trial and error (trust me, I have ES's too). It will take a while to get them dialed in - but once you find it, you'll know it. Everything just snaps into focus.

Bryan


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## pmcneil (May 29, 2010)

Don't sweat the room, get an advanced room correction alogarithm, such as Audyssey MultEQ XT32...


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## bpape (Sep 14, 2006)

And how is Audyssey going to deal with decay time, reflections, etc? It can't - it can only address frequency response issues and only some of those and only those that are common to all seating locations.


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## cyniclaus (Mar 25, 2010)

I re-confirmed my measurements and reflection points last night and am getting ready to order; I will get 2 monster traps for the rear wall and 6 2x4 panels (3 per side between the front and the rear). It looks like the rear of the mains will pretty much be firing into the tri-traps, so I am not planning on treating that side wall area

*If I can fit 244s on the side walls is that always better than using 242s?* I can likely fit them everywhere except directly to the sides of the seats, since they would block the walkway if put there. 

I did realize I could "corner mount" 244s or even monsters to the sides of the seats if they are straddling the space between the wall and ceiling, but I'm not sure how effective or even necessary this would be. I suppose the thing to do is get the basic setup in place and then take acoustic measurements to determine what else, if anything, might be needed


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## bpape (Sep 14, 2006)

I would agree to start with the basics. I'm a firm believer in not doing any more than is necessary. 

The 244's on the sides will do a better job with SBIR and help more with the overall bass decay time in the room.

Bryan


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