Being the frugal one, (learned that from spending time on this forum ) went to Home Depot and bought 9 of these. (3 for each corner-4th corner is not doable because of entrance door) Helped dissipate strong room mode I was experiencing at 63Hz. In addition, seemed to clean up and tighten the bass. As a result, improved overall sound across the board on the cheap.
Nice thing about this, no need to remove plastic wrapping, according to acoustic engineer. Also, said it must be the unfaced kind. You can purchase, stack in your corners, try it out in your setting for a week or two and if you don't hear a difference, take back to Home Depot and get your money back.
Here is the current pricing structure per roll:
Owens Corning EcoTouch R-30 Unfaced 9-1/2 in. x 15 in. x 25 ft. Continuous Roll Insulation
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RIP Bill D.