Superchunk vs. Panel

Is the performance of a Superchunk type corner trap worth the extra material and expense when compared to a panel with an air gap across the corner? I would be doing either a corner chunk with a 2' face of all 705 or a 2' x 4" panel of 705. I would only use 1/2 the material using just a panel. Do you really gain that much absorption with the last few inches of material in the smallest corner space?

Read this, then this.. To answer your question, it all depends on what you consider god enough? A panel has the drawback of being a tuned device, and the only way to confirm it is doing wat you want it to is to test it in situ. Andre

Andre, by 'panel', I think he meant framed 705 (or equivalent) glassfiber 4" inches thick, not the sealed vibrating panel. 1) If you use 705 type, complete fill is not going to make much difference. 2) If you use 703 type, complete fill is going to make noticeable (not huge) difference. I am sure of 2) by personal experience, I am guestimating 1) from all I've read, no personal experience. Cheers, Jean

Thanks guys. And yes, I just meant a piece of 705 going across the face not a wood or plastic panel facing. I'll check out those links. Thanks again.

Just to extend the above argument, I agree that in most cases panels straddling corners are more cost effective and provide almost-as-good performance as filling the entire area behind the panel (ie, the superchunk method). Personally, I think you are better of buying the same amount of absorptive material, and covering more corners. 4" panels covering all corners in a room (including wall/ceiling and even wall/floor) will outperform superchunks in just 4 wall/wall corners, all else being equal.

jwl wrote:

Just to extend the above argument, I agree that in most cases panels straddling corners are more cost effective and provide almost-as-good performance as filling the entire area behind the panel (ie, the superchunk method). Personally, I think you are better of buying the same amount of absorptive material, and covering more corners. 4" panels covering all corners in a room (including wall/ceiling and even wall/floor) will outperform superchunks in just 4 wall/wall corners, all else being equal.

Did you read the second link in my first post in this thread? Cost is the driving factor in it. Andre

I agree 703 (not to mention 705) is expensive, I wasn't so much commenting on which material should be used, but rather the best way to use a given amount of material. 4" panels across all corners will perform better than the same volume of material in superchunks, with less total coverage area.

jwl wrote:

I agree 703 (not to mention 705) is expensive, I wasn't so much commenting on which material should be used, but rather the best way to use a given amount of material. 4" panels across all corners will perform better than the same volume of material in superchunks, with less total coverage area.

We are missing something here. You are writing about using a given amount material, and I am writing about using a given amount of money. For the benefit of others, the significant paragraph is repeated here:

An interesting effect of the pricing is that gapping becomes a non issue. People at times consider having an air gap between the material to increase low frequency absorption. If a gap is used, their has to be some way to keep the material from falling into the gap. Typically this done with chicken fencing and strapping to which it is attached. The chicken fencing costs 50 cents per square foot here. Putting a 3.5” gap behind the Safe N Sound would be over twice as expensive as filling the entire space!

I think you and are in agreement, but seem to be on different paths in our posts. Andre

I think it is best to say it this way, filling the corner will work best, but to keep the cost vs sabins in line use less density when filling the corner. One density does not rule over all products. It depends on what kind of product you are building. Glenn

myfipie wrote:

use less density when filling the corner. One density does not rule over all products. It depends on what kind of product you are building.

Now that is entirely acoustically true. What with porous absorbers is important is the matching of the surface impedance of the absorber to the characteristic impedance of air (412 Rayls). Denser materials have a higher resistivity as a general trend. So a thin absorber will generally be better with a denser material, and a thicker absorber will be better with a lighter material. Cost has nothing to do with the acoustics of fully filled absorbers. It just happens to be a fringe benefit. Acoustically speaking, Andre