# Front Wall Treatment Options



## aps (Aug 11, 2008)

The front wall in my listening room has a centred, fireplace, which extends 1-2' into the room. My plan has been put some super-chunks in the left / right corners with some of the left-over material used to treat the front wall behind the speakers.

Now, after reading another thread I'm now wondering if it'd be better just to fill in the entire left / right alcoves created by the fireplace / chimney. The is approach would entail using exactly the same material as for the super-chunks but would create a mucher trap to give bass absoprtion. (see picture)


Any advice on the "superchunk" versus "complete fill" models would be great.

Regards,
APS


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## bpape (Sep 14, 2006)

Obviously, the solid fill is going to take a lot more material. That said, they also provide a ton more surface area and a much greater thickness than the chunks. That'll give you a lot more control and reach a lot deeper.

The only potentialy drawback would be if there are SBIR issues that could be resolved via tuning the front wall absorption thickness. Likely we could work around this other ways though.

Bryan


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## aps (Aug 11, 2008)

Bryan

Thanks. What material would you recommend? The material I've got lined up for the super-chunks is a local product which is a porous polyester material named Acoustisorb that comes in 50mm sheets and comes in 32 or 48 kg/m3 densities. My big issue is that it'll take a lot of cutting to fill the space and wondering it'd work well to use those large bundles of insulation commonly seen at hardware stores?

Cheers,
APS


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## bpape (Sep 14, 2006)

48 is pretty light but would likely be OK in that thick an application. 

Oh, and while poking around, I found a place in Australia that makes something very similar to 703 and also to FSK.

FSK

http://www.insulation.com.au/content/upload/FI_DS_Sisalation Facing Foil Light Duty (436).pdf


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## ninja12 (Jun 25, 2008)

If my fronts are about 3 to 4 feet away from the front wall, is it still necesary to put acoustic panels on the front wall behind my front speakers?


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## bpape (Sep 14, 2006)

Ideally, the entire front wall should be dead to stop surround reflections. Moving the mains farther out, just changes the frequencies at which SBIR occurs.

Bryan


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## aps (Aug 11, 2008)

Bryan

The idea is to treat the front wall in a manner that allows for better bass response (treatment in the corners) and better spatial imaging (treatment directly behind and between the speakers). The idea of filling the entire recess with damping material combines both with the large volume allowing good bass attenuation.

My question, then, is about whether I could achieve the same result via some panels that extend across the width of the recess but leave an air gap to the front wall. This set-up is shown below and is kind of like a standard corner absorber but across the entire front wall recess. 

The idea of stems from some reading which seems to indicate that a “corner absorber” performs better at low frequencies than a super chunk. I guess, though, that this performance would depend on the depth of the air gap. Any thoughts on the usefulness of this third approach.

Cheers
APS


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## bpape (Sep 14, 2006)

I'd like to see test results of a panel with a gap vs a chunk of the same surface area where the panel performs better - all else equal (material density, etc.)

You can certainly do what you're suggesting but it's not going to outperform a solid chunk. If you wan to do this, keep the depth of the gap behind no bigger than the thickness of the absorbent material.

Bryan


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## aps (Aug 11, 2008)

Bryan

Thanks. I re-read the notes and, of course, you're right. So back to the superchunk / complete fill ideas. You mentioned that 48kg/m3 is pretty light for superchunks / stacked panels. Isn't this the same desnity as 703? Is it necessary to go to 96kg/m3?

Cheers
APS


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## bpape (Sep 14, 2006)

Maybe my math was wrong. if 48kg is approx equivalent, then it will be fine.

Bryan


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## aps (Aug 11, 2008)

Thanks - APS


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