Josh~H

DIY Absorbtion panel design RFC

My DIY Panel

This is looking down at the panel from the top. Instead of building a "drawer" or "tray" style, I put the pegboard halfway between both ends of the frame by routing slats in the side frames. It isn't shown in the diagram, but the insulation will appear on both sides of the pegboard (the panel will be symmetric), allowing absorbtion from both sides of the panel.

The interior of the panel is only 12" wide, with the whole thing being about 13.5" prior to fabric and batting being wrapped around it. A bit narrower than other designs...but that's the size I got when I cut my pegboard in half. The height of the panel is the same as the height of the pegboard, or about 4' tall. When it sits on a stand near the wall, the top will be about a foot higher than ear-level when I'm seated at my HT.

My main concern is the thickness of insulation. Will a 2.25" deep cavity on each side, with 3.5" of insulation + batting, be sufficient to absorb a reasonable amount of sound? I don't know much about the acoustic properties of this type of fiberglass, but certainly if it's compacted past a certain density, it becomes reflective rather than absorbtive. I just want to know if the density I'm using is a useful one.

Josh~H

I just realized I spelled "absorption" wrong (absorbtion). Now why in the world is the verb spelled absorb, but the noun spelled absorption?

Don't answer that question! Instead, answer the question about the value of the fiberglass sound absorbtion coefficient versus density.

Terry Montlick

Hi Josh,

Don't worry about packing the fiberglass too densely. It will absorb even better. If you consider this a 3 1/2 inch absorber, you will get good low frequency absorption down to at least 250 Hz.

You'll get really high absorption at mid-high frequencies with any fiberglass or batting combination an inch or more thick.

Regards,
Terry

Terry Montlick Laboratories
Alpha Certification
The Standard for Home Theater Acoustics
www.tmlaboratories.com

Josh~H

Terry -

Thanks for the advice! My panel will be about 3" thick on one side, and 3" thick on the other -- symmetric, with pegboard in the middle. This allows any sound that goes between the panel and the wall (since I'm putting it a few inches away from the wall) to be absorbed while it's back there.

I won't worry about packing the insulation too densely then. My lower frequency sounds are certainly a bit muddy, but I want to try to tame down the higher frequencies as well, since they're causing fatigue.

MikeWh

It's a Latin thing... ok, I couldn't resist.

Ok.. seriously... from a design standpoint-- it looks a little wobbly... the 1x5s might need some support, like bracing afixed between the pegboard and those sides or maybe 2 end pieces to support the sides.

Josh~H

Mike -

You're correct. Without the 1x5 endcaps screwed onto the tops and bottoms of the sides, it's very wobbly. I did plan for this, but left it off the .pdf doc because it obscures everything in the top-down view.