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In the Forum: Horn-Loaded Speakers
In the Thread: Bill Gaw: over 50 years of high-end audio experience and time aligned horns.
Post Subject: Answer to RomyPosted by Bill on: 10/30/2025
A 30 Hz. Wave Has a 1 meter wavelength. If one takes 12 inches of this insulation and places against the back wall, it should absorb 30-40 percent of a 30-40 Hz. Wave.ii placed about a foot away from the back wall it should absorb at least 50-60% above 30 Hz. And 100% above 90 Hz, if one extrapolates from the diagrams below. That,s obviously theory. But obviously Romy heard something. Whether that is the cause or not of the improvement, all I can say is that nothing else changed in the room to cause the improvement.a Interestingly, I went around the room last night, played a 20 Hz. Up sweep and noticed a definite decrease in the hills and valleys of bass sound volume in the low bass region. So the bass panels definitely are cleaning the low frequency muddying of the back wall reflection.
(Insert the two diagrams here.)
So experiment. The batts cost $99.00 each for 12 inch thick 2 x 4 feet packages. Line them up 2 to 3 high depending on room dimensions about 1-2 feet from the back wall and kitty-corner in the room corners. Cut out about 80-90% of the front and back cardboard leaving a 3 inch wide band of cardboard for strength to allow absorption of all wavelengths.Make sure you get the one shown below from Amazon or Roxy l as they are half the price of Owens Corning 703, but have almost the same acoustic absorption specs. The typical room may need 7 to 10 of them. My woofers and subs lay against a wall so there are no side reflections of bass, but for those whose speakers are a distance from the wall may get some improvement placing one at the first reflection point of the woofer and subs side walls.
(Insert Amazon picture here)
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