Originally Posted by badger985
Just to clarify the 703 FRK only has the foil reinforced on one side, thus if I slap that together with a regular piece of 703 2" to create a 4" trap, I will still get the benefit of the Foil Craft, and the enhanced Sound absorption at 125hz?
Skip the FRK/foil. Membrane absorbers require an expert. If you understand how to make a membrane absorber, and how to measure/calculate the effects of existing wall resonance on the membrane, you're better than me. If you measure and discover you need a tuned membrane absorber to deal with a pesky room mode, look at a professional one like RPG Modex
Mineral wool (including fiberglass), and corner traps, of just mineral wool and acoustically transparent cover fabric, are idiot proof.
1) soundproofing is good
2) knock first reflections down by at 20dB
3) deal with room modes. Minimalist techniques include tri-corner traps and subwoofer placement.
4) no chairs higher than your shoulders
5) wide frequency absorption, not high frequency absorbers