Originally Posted by neuro
the rockwool i bought came with kraft paper on one side. i was planning to remove it for building these early reflections panels but reading what you all (Hannes, DanDan, Avare) say, i believe that leaving this on the airgap side of the panel would be beneficial for the overall bass absorbtion in the room, right ?
would this kraft paper act as a membrane ? or is it too thin and should i glue an extra layer (of thin foil maybe ?) to it ?
i'll definitely make 6" (2x3) thick panels (+ 6" gap from the wall), removing kraft from the outer rockwool panel, and maybe leaving this kraft paper on the inner one (the one closest to the wall), depending on what you recommend.
What is the density of the mineral wool? With 12" total depth, if the mineral wool is ~4 lb/ft³ you will have excellent low end absorption. We do not have enough test data to give a professional recommendation to keep the FRK. Having written that, without test data, I do not see it causing any significant degradation in the worst case that I can hypothesize.
Note all the qualifiers in the last sentence.