# YLZ theater acoustic treatments



## zacjones (Mar 25, 2007)

OK so I think I'm ready to start doing some room treatments on our theater. The theater is not going to be the end-all design as there are some inherent problems with the layout, but as it is a shared living space we are going to have to make the best of it. I'll post some actual photos here in the near future, but here is the room as it is now. 





































I understand that the theater being wider than it is deep poses some problems, but it just has a better feel to it this way. I'm hoping to be able to manage the openings in the rear of the room, and take advantage of the landing area behind the theater for added acoustical depth. We did physically try various configurations, and determined this layout to be the most acceptable. The runner up was closing off the windows, building a false wall to make the theater symmetrical, and orienting the theater lengthwise, but we felt we just weren't ready to lose the open feeling of the upstairs, so here we are.

The room is 20' wide x 12.5' deep x 9' ceilings. The alcove is 18" deep, so in the section that houses the screen and front speakers the room is 14' deep.

The inaugaral speakers are Klipsch RF-63's for mains, RC-64 for center, and RB-6 bookshelves for side surrounds. We're considering some matching ceiling speakers for rear surrounds in the landing area behind the theater, as there really aren't any good places for traditional surrounds. These will all be replaced as budget allows with some DIY gems like the Clearwave Dynamic Series, but for now these are what we have to work with.

The screen is a 120" diagonal Da-Lite Hi-Power that we've used in two previous theaters. It's on its last legs here, and will eventually be replaced with an AT screen that will pull down directly in front of the front stage.

But I think that the equipment we have will allow us to setup room treatments that should hold up as the theater matures.

The plan is for subwoofers IB in the floor (the theater is over the garage). I still have eight IXL 18.4's that I purchased on the original group buy four years ago. Four of them still new in the box! I'm thinking the eight IXL's will do it. If they don't get it done I'll have no choice but to install 48 transducers onto the sofa! :yikes:

All kidding aside, I plan on running down to the local HVAC insulation supply and picking up a stack of rigid fiberglass panels next week, and trying to figure out what to do with them. So hopefully someone who's done this before can give me some tips along the way. 

First off -- what are first impressions on what kind of the absorbers, traps, and diffusors I might need where would you first think of placing them?

If I had to guess at where to start, I would think of something along the lines of:

(1) two or three of the 2" absorption panels on the side walls and ceiling for first reflections
(2) some triangular stacks for the front outside corners and the front recess corners
(3) if I can still fit them in some more 2" absorption panels on the front wall behind the mains and center channel. 
(4) some sort of bass trap directly behind the sofa on the back wall -- if it was deemed I should indeed move my sofa off the back wall. I know that typically one would definitely do so, but with all the openings on the back wall I thought it might be OK to leave the sofa on the back wall. 
(5) some diffusors on the back wall? Not sure where they'd go or if they'd be necessary. 

How far off was I? I'm hoping I was at least close.

I do have a calibrated Galaxy CM-140 and USB soundcard that I've never used, but I'm eager to put that to use here as well. I'll try and educate myself on how to put those to use with room correction and acoustic treatments, but if anyone has a useful, informative link on how to get started it would be very much appreciated.

Thanks for reading through my lengthy first post, and for any thoughts or suggestions you care to share. Zac.


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## bpape (Sep 14, 2006)

I would cover the recessed area in the front (including sides) with 2" 703 or equivalent.

Chunk style absorbers floor to ceiling in the 2 outer front corners.

Side reflections as you described.

On the rear, it really depends on where your head is in relation to the opening height wise.

Bryan


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## zacjones (Mar 25, 2007)

Thanks Bryan. I really appreciate all the work you put into helping people out on so many forums. Amazing really.

So either 24"x24"x34" superchunks or 24" square columns in the outside corners, spaced 4.5-6" out from the walls (There is crown molding that extends 4.5"). Doing it in OC703 would run about $350-$700 for the two corners, depending on if we did the triangles or the square columns. Going with rockwool for these would cut the cost of the corner treatments in half. The 3# density is available here in 1",2", and 3", while the 4# density is available in 4". Which one of the rockwools would you go with, weighing both the acoustic properties and ease of construction?

Is it important for me to get measurements of my subs in room first before trying to determine whether to do a superchunk triangle trap vs the column trap and what material to use? Or is it a pretty safe bet that the triangle will provide good end results and the columns will provide better end results?

(2) OC703 2" panels on the each of the side walls, spaced 1-2" off the walls with french cleats.

Either (3) or (4) 2" panels on the ceiling, similarly mounted. Is this overkill on the ceiling?

If I wanted to get a beveled edge on the 2" OC703 panels, how does it hold up against a router and a chamfer bit?

Here's a shot of my understanding as to where the treatments should go.










Thanks. Zac.


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## bpape (Sep 14, 2006)

That's a TON for 703. You can do 17x17x24" triangles and do 8' tall with 6 pcs of 2" 703. Mineral wool can work but it's a real pain to cut cleanly. 

The measurement beforehand will only be useful in helping you best place your seating, subs, and mains. 

Bryan


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## zacjones (Mar 25, 2007)

The reason I shied away from the triangle traps in the corners was that I didn't want to cover up the crown and baseboard. I do have extra crown and base though, so I guess could install the traps tight into the corners, and then install crown and base across the front of the traps. Any significant downside to doing this? 

If I did do the 24" columns out of the mineral wool would that be overkill, or even go so far as to have a negative impact? How much dead space could I leave between the corner walls and the columns without losing effectiveness? 6 inches? 12 inches?

I will be running a lot of subs -- between 4 and 8 high excursion 18's IB in the floor, likely between the mains.

I think I might have a good way to cut the mineral wool up my sleeve...


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## bpape (Sep 14, 2006)

You'll be fine with a 6" gap and 24" square columns.


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## zacjones (Mar 25, 2007)

Wow those columns were FIRMLY rejected by my wife!

So I guess we'll be doing the corner traps then like you suggested...

Will having the crown and base installed over the front of the trap have any significant negative impact on the function of the trap?

thanks. Zac.


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## bpape (Sep 14, 2006)

Maybe it was that lime green color :rofl:

What a lot of people do is cut the base and crown, install the treatments, then do the crown and base back on the face of the treatment. Makes for a nice clean look.


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## fitzwaddle (Aug 25, 2010)

bpape said:


> Mineral wool can work but it's a real pain to cut cleanly.


I used an electric carving knife to cut my SuperChunk triangles out of Roxul AFB, it worked great - nice clean cuts, and cuts it very easily. I was able to get the 3" Roxul AFB much cheaper than 703 here locally - about $90 for all four corners (almost) floor to ceiling.


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## zacjones (Mar 25, 2007)

Thanks for the info. I think that we will do something along those lines too. Wow--love your theater. I wish we could do something like that. If I could just get her to forget we had a window in that recess I could do some kind of baffle wall or soffit there with a fixed AT screen. Now if I can just figure out a way to make it her idea...:innocent:


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## zacjones (Mar 25, 2007)

Well speaking of acoustic treatments we got the AT screen! A great deal just sort of fell into our lap, and we couldn't say no. A one year old 130" diagonal SeymourAV Centerstage XD retractable, tensioned, electric 2.40:1 format AT screen in near perfect condition for about fifty cents on the dollar locally. 

Everything's starting to come together now into a solid plan. Exciting. I talked to Jed at Clearwave Loudspeaker design and we came up with a plan for a shallow, sealed version of the Dynamic 4T SE towers with custom crossovers to allow near wall placement. These three tower speakers will be designed to be pushed all the way tight up against the wall, behind the screen, which will end up hanging flush or just past flush with the walls flanking the recess. Thanks again for your advice bpape and fitz!


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## zacjones (Mar 25, 2007)

And now the budget for the acoustic treatments is no more. Until next month. Or the month after.

To be continued...


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## fitzwaddle (Aug 25, 2010)

Sounds like a great deal on the screen! :T

Where's your build thread with all the pictures? :bigsmile:


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## zacjones (Mar 25, 2007)

Heh heh. So far I could show some pictures of my wife and I painting, but that's only slightly more interesting than actually watching it dry.

:yawn: 

Good idea though. I suppose now is a good time to start one. I can probably even find some pictures of before and after the painting!


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