# How much absorption do you want in a room?



## matthewmathis (Nov 11, 2008)

My home theater room is unfinished at the moment and I had the idea of stuffing each stud bay with 4" think mineral wool and then covering all of the walls with fabric. My room would then have an incredible amount of absorption, but is it too much? If it is, should I just leave some some stud bays void of absorption? Should I use some diffusion instead? Please advise as I am a little lost.


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## Pinhead-227 (Dec 24, 2008)

I've wondered that as well. I've often wondered how a theater system would sound in a psych ward's padded cell.


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## matthewmathis (Nov 11, 2008)

You would think with all of the info out there we would be able to find an optimum % of wall coverage. I called Auralex and they said to just use as much as possible, but I think a second opinion from someone not trying to sell me product is needed.


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## JimP (May 18, 2006)

I think your room would wind up being too dead if you went with having 4" in all wall positions.

There are general recommendations about putting a certain kind and amount of absorption in different places. 

One of the more sensible post I've read had to do with starting off with treating the front wall and then start running test to see what your room was doing before adding more. You may find yourself building a helmholtz (sp?) resonator as part of your risers.

One thing to watch for on one of the vendor websites they're showing how much adding absorbers helps, but they start off with hard surfaces everywhere and no furniture. In the real world, furniture and carpeting act as absorbers. So your results are not going to be as dramatic as what they're showing.


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## matthewmathis (Nov 11, 2008)

I thought that it may sound dead. The only problem with the front wall approach is that I have to make a decision on to sheet rock, do this crazy fabric wall, or a mix so that construction on the room can start.


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## JimP (May 18, 2006)

Probably not what you want to hear, but redoing walls is more expensive than doing it right the first time. That also applies to buying stuff you don't need.

On a seperate thought, I've seen home theaters where everything was hidden. You didn't see any weird stuff hanging on the walls and all speakers were hidden. On the other extreme, I've seen rooms that looked like recording studios. If you're aiming for the first and not the latter, you really need to either put in a lot of time figuring it out or as a friend of mind did, just hire someone to do the design work for you. Given that you're in a bit of a time bind, I'd hire it done.


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## bpape (Sep 14, 2006)

The room will be WAY too dead if you just cover insulated stud cavities - not to mention having basically zero isolation in either direction.

Bryan


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## fredk (May 14, 2008)

The idea of using some of this space for absrbtion does seem like a good idea.

Bryan. What if he were to use the the space between the first two studs in each corner using something like a 3lb mineral board? You could then put in additional corner traps as needed after doing some listening and measurements. It seems like a good way to increase bass absorbtion in the corners.

Thats probably not a good thing for sound isolation though.


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## bpape (Sep 14, 2006)

Exactly. It will help one thing at the cost of another. Also, even with the stud cavity being full - 3.5" isn't really going to get you way down into the subwoofer range - espcially not 'flat' like that. A 4-6" panel straddling the corner is MUCH more effective.

Bryan


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