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Old 05-02-2007, 03:12 PM   #38
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Location: Columbus, Ohio
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No, it actually adds to the bass response. Note in my instructions I state specifically to remove the foil from certain places. It should only be on the surface facing into the room.

From Ethan Winer:

For a given thickness, 703 is about twice as absorbent as acoustic foam at the lower frequencies, and it generally costs much less. Even better for low frequencies is 705-FRK, which is much more absorbent than 703 at 125 Hz and below. FRK stands for Foil Reinforced Kraft paper. This is similar to the paper that grocery bags are made of, but with a thin layer of metal foil bonded to one side. The FRK paper was not intended for acoustic purposes, but to serve as a vapor barrier in homes. It just happens to be good acoustically too. Be aware that the paper reflects mid and high frequencies when installed with that side facing the room; this may or may not be desirable for a given application. 705 is also available without a paper backing.
Full article here:

The highs and mids were easy to knock down in my room with a few mid/high absorbers, so the little bit of reflection from the FRK in mid/highs was far outweighed by its benefit in the lows. At 125hz, 6pcf material with the FRK facing absorbs nearly 50% more than without.

Last edited by Bubbagump; 05-02-2007 at 03:18 PM.
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