# Building my own 2'x4' absorption panels... is 8LB density too dense?



## Talley (Dec 8, 2010)

Have a local company where I can buy 2x4 slabs of 2" thick 8lb density minwool panels for $0.52sqft. They come 6 panels to a box of 48sqft total and the price is phenomenal at $24.96 a box. Gonna pick up 3 or 4 boxes tomorrow depending on the verdict here.

is 8lb density too thick to absorb higher frequencies? I'll be using the Jet Set fabric to cover my panels. 

I want to make some triangular panels for the wall/ceiling corners and make some that are 12"x4' and pattern them to kinda create an art like appearance (however adhering to the location/as needed basis).

Mainly want have some diagonal panels in the corners where I could double up for 4" thick and/or thicker if need be for some bass traps.

Now... I can buy the same material but in 4" thick and it's only 4lb density but it's $0.76sqft so ~30% higher cost but it's less denser but thicker.

I want to do some diffusion later down the road however I need absorption to kill the ringing my room has and want to do that before I get my screen up.

Anyone have experience that can comment?


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## bpape (Sep 14, 2006)

The 8lb would be fine for bass absorption. I would use the lighter density for the side wall reflection panels.


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## Talley (Dec 8, 2010)

Thats what I figured. I wonder if I could split the 4" 4lb density board in half. It'll be wrapped in fabric so asthetics wouldn't matter much.


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## Talley (Dec 8, 2010)

Well... $105 after tax I picked up 16 panels of 4" thick 4lb density 24x48" minwool material.

I can cut these in half... make triangles for the wall/ceiling corners and do whatever with them. If I just made 16 panels then the total estimated cost is around $220 for a DIY setup.

I think that is a steal considering this is 4" stuff.


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## Talley (Dec 8, 2010)

I'll end up for the 2'x4' panels will just use 2x6 lumber. I'll buy 12' long so each piece will make one frame. Then I'll use 2"x2" furring strips to run some pieces on the back horizontal which are actually 1.5" thick and the fact the 2x6 is 5.5" thick that leaves a perfect 4" depth to insert these panels into.

This also will leave a 1.5" gap between the panel and the wall. 

Total cost will be $22-24 for each panel. Me happy!


OR... just use these panels: http://www.lowes.com/ProductDisplay...gId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1

which would make 4 pieces 2'x4' and attach it to a 1"x2" furring strip frame and then lay the panel on it and wrap the fabric around this way it works on all 4 sides too. I could glue the panel to the wood panel and the back frame would give it enough structure for mounting.... this brings the price down to about $18 each.


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## Tonto (Jun 30, 2007)

You might consider using just a 1X4 for the frame & make a 2" (or whatever width you prefer) French cleat to hang them with.

What was your plan for the hardboard?


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## Talley (Dec 8, 2010)

to act as a backer.... by using the hardboard as a backer and a 1x frame the frame would also get the french cleat to mount to the wall but using the hardboard I would glue the insulating panel to at to help support it and then wrap the entire thing in fabric. This way 100% of the sides are exposed.

Won't know yet till I get started though. Will build 4 this weekend then just listen for a few weeks and add as needed.


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## Tonto (Jun 30, 2007)

Just thinking about getting better absorbtion with a gap between the panal & the wall.


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## Talley (Dec 8, 2010)

Tonto said:


> Just thinking about getting better absorbtion with a gap between the panal & the wall.


Correct. Which is why the 2x6 would leave 1.5" off the wall.

Now I'm thinking of just building a frame out of cheap 1x2 furing strips. Basically build a cage out of 1x2 wood and then slide the insulating panel into it and then build a stand off frame to keep it off the wall. Ideally I would have about 4" gap there.


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## Tonto (Jun 30, 2007)

I think the backer board would defeat the purpose of the gap (would act like the wall).


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## NBPk402 (Feb 21, 2012)

Originally I was going to leave a 1-2" gap behind my panels, but I ended up for going the gap, and doubled up on the thickness of the panels. I have heard that the thickness of the panels is more important than the gap (with both taking up the same wall depth).


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## Talley (Dec 8, 2010)

Tonto said:


> I think the backer board would defeat the purpose of the gap (would act like the wall).


using a thin board say 1/4" to 1/8" thick.... but have a square frame build around the edge on the back side of 1x2 material allows the entire middle of the panel to be loose but creating a back for the fiberglass to lay against.

This board would then be 3/4" off the wall and then I would have the entire 4" thick panel exposed. The panel would allow movement/vibration which would work with the minwool panel to absorb low frequencies.

Take a look at this site for a general look: http://www.sae.edu/reference_material/pages/Coefficient Chart.htm

notice that plywood paneling that is 3/4" thick has little low frequency absorption because it's TOO stiff. Then you get down to 1/4" and it's low end is better than it's top end. This because it's too dense and the higher frequencies bounce off while the lower frequencies gets SOME kind of absorption because of how thin it is it can vibrate and absorb naturally. Take a look at 3/16" paneling over 2" air space. It's most effective at 125hz with a .38 but does nothing above 500 essentially.

This is why building a corner trap that is just 4" thick going over the corner at 45 degrees works just fine compared to filling the entire corner up with material.


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