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Originally Posted by ejsongs  so what you are saying it that you would use 4" of 703 and then an appropriate air gap to sort of tune the trap to deal with a rage of low frequencies.
how you do predict what the air gap should be? for a specific example i have an issue around 125hz and 140hz...i think because of the dimensions of my room 14x12x8.6 i have modes there...so is there a graph/chart or formula that would say that to dealing with these frequencies and this thickness of 703 which has these gasflow properties ishould make a panel that has this x air gap? how do you know?
or in this specific instance what would you do? 
j |
For what you are describing use 4" of 703 with a 4" gap. The equal values of material and gap is coincidental.
Andre