# treatment? (pic)



## PoorSignal (Jul 23, 2009)

How do you suggest I treat the front plane of the room? Picture included..

My speakers in the back are up high sideways facing towards each other, because I sit against the back wall 
In that case is treating the front of the room still important?


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## Matteo (Jul 12, 2006)

Nice Energy speakers. I have the same center in my Big TV room, but use the RC-70's. I think, but am not the expert, that it is "generally" a good idea to have a dampened front wall and a reverberant back wall. After that, you can treat your side walls as needed and the corners with bass traps. Unless you have a way to measure your room and the responses it yields, it might be hard to know exactly what you need. 
Here is an interesting article. Has a lot of suggestions.
http://www.ethanwiner.com/acoustics.html

Matteo


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## bpape (Sep 14, 2006)

I would agree on deading the front wall. I would also add that when you sit right against the rear wall, some thicker absorption behind you will be necessary to minimize the bass buildup and 'boom'.

Bryan


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## PoorSignal (Jul 23, 2009)

Hi, more info, here is the sitting area and the red bean bag indicates where I most likely rest my head... (facing the center of screen and speaker).

I only have about 3" inch behind the sofa so I want to know what is the best material that could be the thinnest. 

I found these 2.5" foam here, the specs seems OK, I mean it is not exactly bass trap.


http://www.sonexfoam.com/sonex_vlw.html 

Would it work to use this or similar 2" material for maybe 6" the chair back and then transition to 4" panels?


I also found the reflection point of the front left channel using a mirror. The right channel is close to an upper cabinet so can't do much there.
I know the desk hutch is not helping any! but everything is a compromise.

I have a EMC8000 on the way so I can experiment a bit.


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## bpape (Sep 14, 2006)

Well, the best thing to do is fix the problem. Move the seats away from the wall a few inches, or as much as you can. 

Foam is about the worst solution in terms of performance. You're not going to get broadband bass control from 2" thickness no matter what - but 703 or 3lb cotton will do considerably better than foam.

Bryan


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## PoorSignal (Jul 23, 2009)

If you were me and only have the time to work on one end right now, it would be the rear wall first right?

Also do I want to put a 4" bass trap on subwoofer first reflection point as well as the mains? What if I can only do first reflection point on the left side of the room?


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## bpape (Sep 14, 2006)

Try to maintain symmetry left to right in terms of treatment - unless one side is already 'soft' and absorptive.

No need to do reflection points on the sub - they're everywhere as bass radiates spherically in 3 dimensions. 

If it were me, I'd move the seating out a bit and kill the rear wall with some thing thick first.

Bryan


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## PoorSignal (Jul 23, 2009)

For the front I could put in 2 pieces of 2" OC703 2'x4' starting about 1/3 from the bottom of the TV, up to the ceiling on each side, part of it tucked behind the TV, because I don't want to cover the light switch.

Then 1 piece 2x3 or 2x4 sideways above the TV. Basically the TV will be surrounded on the upper half.

Do you think that works for front treatment?


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## bpape (Sep 14, 2006)

That should work OK to help with boundary reinforcement from the wall mounting and also to help tame surround reflections off the front wall.

Bryan


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## tcarcio (Jun 27, 2007)

Brian, So your not supposed to treat the rear wall? I have two 2'x 4' panels of 703 right behind the listening position so should I use them elsewhere? I hope you don't mind me asking that here Jeremy.


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## bpape (Sep 14, 2006)

Treating the rear wall is usually done with something thicker to tame bass anomolies. It's not really a reflection thing.

Bryan


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## tcarcio (Jun 27, 2007)

OK, So I should probably take my 4'' thick panels off the side walls and put them in the rear corners? I then could use the 2'' thick ones from the rear wall and put them on the side wall. Does that make more sense. Thanks Brian.


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## bpape (Sep 14, 2006)

I'd use the 4" panels directly behind your seating, not in the rear corners. The 2" panels will do fine for side wall reflections and front wall duties.

Bryan


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## tcarcio (Jun 27, 2007)

Great, I appreciate the advice............... :T


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## PoorSignal (Jul 23, 2009)

Hi, here is a quick measurement of the bass range I did.
Red is unadjusted,
The green is adjusted with 2 band PEQ, until I get the DSP1124.

I understand this graph does not tell me the clarity of the sound, the higher frequency chart is much more undesirable.

it seems a decent starting point for bass response, should I focus on applying 2" panels instead of thinking where I could hang any 4" panels and bring the whole WAF down :boxer:

I plan on framing 1"x3" with 2" insulation so it leaves 0.5" air gap behind it. Without making the panels too overly thick.


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## PoorSignal (Jul 23, 2009)

I found out with individual sweeps of sub alone, vs L R alone, the room mode excites around 55hz, would it be possible for me to get a 4" thick bass trap and place it around different areas, to find if my desk or a certain corner is doing that?


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## bpape (Sep 14, 2006)

55Hz is getting pretty low. You need to identify WHERE that 55Hz is coming from. Most likely, you'll need something 4-6" with a couple inch gap behind to really deal with that.

Also, what, if any smoothing did you apply to those response graphs you posted. Try with no smoothing.

Bryan


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## PoorSignal (Jul 23, 2009)

Thanks, I am indeed trying to idenitfy where it is coming from, if it was a corner or a bookshelf or a hutch or something. I would see if I can do something to address that, or decrease it if it is possible.

There is no smoothing in my graphs.


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## bpape (Sep 14, 2006)

If there's truly NO smothing in the graphs, that's outstanding response. I'd take another set with the mic 1' to the left and another 1' either forward or back from your current position and try to see where it's coming from. It's obviously not speaker/sub related in terms of SBIR.

Bryan


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## PoorSignal (Jul 23, 2009)

I just loaded up the software and use it, are there some default smoothing that I need to turn off.

I noticed there is a 1/3 smoothing in the menu, but I didn't use that.


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## bpape (Sep 14, 2006)

You should just slect no smoothing.

Bryan


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## tsaelee (Feb 28, 2010)

tcarcio said:


> Brian, So your not supposed to treat the rear wall? I have two 2'x 4' panels of 703 right behind the listening position so should I use them elsewhere? I hope you don't mind me asking that here Jeremy.


Rear wall is typically best use as diffuser area. I built floor to ceiling bookshelves and populate with all kinds of different books. I know it's probably not the best diffuser method but I think it works well. You want to treat the reflection points with oc 703 or other sound treatment panels.
_Posted via Mobile Device_


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## bpape (Sep 14, 2006)

It all depends on what problems you're trying to address. If you have bass cancellations off the rear, then thicker absorption with a damped membrane are your best bet to address them.

Diffusion requires a certain distance from it to your ears to function properly which many home theaters do not have. Boookshelves, if anything, will act as aborbers, not diffusers except at very very high frequencies.

Bryan


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## tsaelee (Feb 28, 2010)

Right, bookshelves should work as diffuser for the higher frequencies. How efficient, I have no idea. Bryan, you probably have a better grasp in this field. How effective is sound treatment if the room is not completely enclosed and with large windows, I supposed it'll help but not that much. Are corner bass traps really effective dealing with low frequencies, from 80 Hz and below? I have a dedicated HT room with only the front corners treated but not the rear corners. Do you have any suggestions?

Thank you.


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## bpape (Sep 14, 2006)

How low a treatment will reach is a function of thickness and density. Some corner absorbers can reach well below 80Hz. 

Windows will actually pass a bit of the bass out of the room. Not totally enclosed just means that you're actually dealing with a larger room and longer decay times than just the area you're using as the home theater. At some point, it's all enclosed by the exterior walls.


Bryan


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