# Need Advice!



## cyniclaus (Mar 25, 2010)

Hi all,

This is my first attempt at a semi-serious HT, so I appreciate your advice and patience. I've never used acoustic treatments before. :rolleyesno:

I need some advice for inexpensive temporary acoustic treatments for my new HT. When I clap my hands in the room there is some real bad flutter echo. Temporary because I will be moving in a year or two.

As you can see in attached pictures, room is painted a neutral gray with a flat black ceiling. It's a 7.1 setup with Klipsch Synergy III. Sub is a MFW-15 location TBD (thinking behind the seating neat the pole) :scratch:

Dimensions are 18'8" deep by 12'8" wide (14'8" where the alcove is).

Just put in thick carpet with a 1/2-inch pad. Ceiling and walls are 1/2-inch drywall. There are no windows and the room is pretty much airtight except for an HVAC vent above the door from the ducting that is contained in the soffit. The ceiling is 8ft except under the soffit where it is 6'8". All equipment will go in the alcove you can see to the left of the door and I plan to cover it with a heavy, light-blocking curtain. Door is solid core and weatherstripped. I was planning on lining the back wall below the rear speakers (under the soffit) with DVD shelves.

Yes, that is a post you can see right in front of the left surround speaker...it is a disguised structural support pole and a necessary compromise due to this being part of a remodeled basement. I'm thinking impact should be minimal as the two rows of seating will both be in front of the post/soffit

I don't have a specific budget for acoustics but, being a temporary setup, I'd say in the nieghborhood of $1000 and less is better :spend:

Right now, I'm considering stacking 2x tri-traps on each of the front corners and hanging some panels on the front half (GIK 242s or Auralex sonoflats) at primary reflection points. The ceiling paint is textured, cottage-cheese type...not sure if that would diffuse enough or if I should put panels up there as well. 

For the back half, I understand you want diffusion behind the seating area? Not sure on this. :scratch: 

For rear bass control I'm thinking of sticking some LENRDs up where the ceiling meets the soffit, and possibly on the back wall/soffit junction as well if warranted. I'm thinking I might need another tri-trap in the corner back there to cut down the boom. Do you guys think that equipment alcove is going to have a significant negative impact on my bass, or could I leave that untreated? Man, this sounds like it could get expensive :doh:

Any advice is greatly appreciated. :bigsmile:


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## Prof. (Oct 20, 2006)

cyniclaus said:


> Right now, I'm considering stacking 2x tri-traps on each of the front corners and hanging some panels on the front half (GIK 242s or Auralex sonoflats) at primary reflection points. The ceiling paint is textured, cottage-cheese type...not sure if that would diffuse enough or if I should put panels up there as well.


That's fine...I would also consider stacking the rear corners as well with tri-traps.. 



> For the back half, I understand you want diffusion behind the seating area? Not sure on this. :scratch:


You'll need to put a couple of panels on the back wall that have FSK facings. These will give you a balance between absorption and reflection..
I would just try those treatments first and then see how it sounds..You can always add more later if need be.. 



> Do you guys think that equipment alcove is going to have a significant negative impact on my bass, or could I leave that untreated? Man, this sounds like it could get expensive :doh:


The equipment alcove shouldn't be a problem..


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## bpape (Sep 14, 2006)

If you're going to use diffusion in that room, the only 2 places I would recommend it would be on the rear portion of the side walls and potentially at the ceiling reflection points.

Bryan


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## cyniclaus (Mar 25, 2010)

Thanks for the help so far! 



Prof. said:


> That's fine...I would also consider stacking the rear corners as well with tri-traps..
> 
> You'll need to put a couple of panels on the back wall that have FSK facings. These will give you a balance between absorption and reflection..


I love symmetry, but this is an asymmetrical room...with the low ceilings under the soffit, I can't stack two traps back there, and my rear-right "corner' is my equipment alcove. I realized (unfortunately _after_ they did the framing :doh that I should have just made the alcove deeper and put a door on it, essentially making it a closet. As is, I was able to fill the first half by mounting my wooden rack in flush sideways so it basically extends the wall back and then cover it all with light-blocking heavy black suede curtains, which is not half bad...makes me feel like the Wizard of Oz when I go in there "Pay no attention to that man behind the curtain!" 



bpape said:


> If you're going to use diffusion in that room, the only 2 places I would recommend it would be on the rear portion of the side walls and potentially at the ceiling reflection points.
> 
> Bryan


I guess you're saying diffusion may be unnecessary in a room of this size?

Well, to start I guess I'll go ahead and order 4 x Tri-traps to start. I'm undecided between getting 1 pack of 3 242s or just go ahead and get 6. I see you can save some money with your "room kit" that has 4 x Tri-Trap, 6 x 242, and 1 x Monstertrap, but I'm not sure if I need a Monster or where I would put it. :scratch:


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## bpape (Sep 14, 2006)

2 monsters centered on the rear wall would work well in taming length related axial modes and cancellations off the rear wall.

I don't think diffusion is an absolute requirement in most rooms. There are other things to address first before I'd go down that path.

Bryan


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## cyniclaus (Mar 25, 2010)

bpape said:


> 2 monsters centered on the rear wall would work well in taming length related axial modes and cancellations off the rear wall.


Hmm, that's an idea...but if you mean to hang the panel between the two rear speakers, then only one would fit...there's only 39" between them, which was the best I could do for separation given the size and layout of the room. Do those Monsters treat high frequencies as well, i.e. working like an expanded-frequency version of the 242s, or are they strictly for low freq treatment?


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## cyniclaus (Mar 25, 2010)

BTW, Would it be a good idea to treat the wall behind my screen? That's a huge area and since it is hidden, it wouldn't have to be pretty...I could even hang a carpet on the wall or something.


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## bpape (Sep 14, 2006)

Carpet won't do anything but kill high frequencies.

The monsters roll off high frequency absorption by design so we don't overkill things trying to get the bottom end under control. We can custom size these also as needed to fit.

Behind the screen will not give you any high frequency absorption either due to the screen but it could certainly help in the dialog range.

Bryan


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## cyniclaus (Mar 25, 2010)

OK, for now I ordered the 4 tri-traps from GIK, a set of LENRDs for the soffit/ceiling angle to frame the projector, and an Auralex Studiofoam Designer Kit for the ceiling.

I still am undecided/unsure on the wall treatments...the Klipsch surrounds have the side-firing horns and I need to figure out how thick I can go with panels without the horns firing right into them. I also want to be sure whatever I use will be aesthetically sound; the room looks fantastic right now and I want to keep it that way if I can. I'm looking at the 242s, ATS microsuede, and Sonoflats


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## bpape (Sep 14, 2006)

The 242's at the reflection points shouldn't cause any problems for the surrounds and should tighten things up as far as imaging and screen lock for the dialog. They'll also reach farther down than the other 2 you mentioned.

Bryan


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## cyniclaus (Mar 25, 2010)

Man, this is way harder than it should be! I spent the weekend mapping reflection points on my ceiling and walls 

I've figured out I need 4 panels (2 each side) in 2x4' for primary reflections on the walls between the surrounds and the front speakers.

Then, I need 4 panels in 2x2...1 each for under the surrounds and 2 for the back between the rear surrounds.

Eventually, I may get 5 more 2x4s...1 to treat the door and 4 for the walls aft of the seating area

I have done a lot of research comparing the GIK, ATS, and others and it seems that GIK provides the best performing product for the money. The 242 is $60 for standard fabric and $75 for GOM. What I can't determine is what the standard fabric is and if it will look good enough in my space. I'm assuming it's the same as the fabric on the tri-traps I ordered, but it will be a while before I see those. :scratch:

ATS has 2x4s for $52 in microsuede--50% the cost of the cost of 242s in GOM--but they sit flush with the wall, so their low-end absorption should be poor compared to the 242s. The other problem is that GIK only makes 2x4 panels, so I would have to buy all from ATS if I want the fabric on the 2x2s to match the 2x4s which will be only a few inches away from each other. :doh:


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## bpape (Sep 14, 2006)

We can do custom sized panels though there is an upcharge for them. Yes - 242's will vastly outperform the ATS 2" panels in the bottom end.

Not sure why you'd need 2x2 panels under your surrounds. Are you talking about rear surrounds? If so, then something more like 244's for some deeper bass control off the back wall would be a better solution rather than trying to catch rear wall reflections from the front speakers. Those are pretty much on axis and relatively late to be considered as destructive.

Bryan


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## cyniclaus (Mar 25, 2010)

In my picture you can see the space under the surrounds...the woofers on the surrounds cross each other above the seating so that about a foot down from the surround itself is the primary reflection point of the surround on the opposite wall (room is about 13 ft wide). I suppose a 2x4 would fit there, but it would be overkill acoustically and would not look as nice. On the back wall, however, I need to use 2x2s as I am placing DVD shelving that will not leave enough clearance for a 2x4 panel. the best acoustic solution would be leave the SW between the rear surrounds with a 244 or monster mounted above it, but the SW is huge and would an ergonomical nightmare there, sticking over 2 ft out from the wall. I was thinking the corner would be the best place for it, but whereas the CW used to be to put your sub in a corner, now people say it's bad. :huh:

Can you speak to the difference between the standard fabric and the GOM?


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## bpape (Sep 14, 2006)

I wouldn't worry too much about those side points personally. If you want to do something there, a larger panel is certainly not overkill given the restrictions on where we can place panels in the room to achieve proper overall decay times.

Bryan


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