Best way to absorb below 100Hz
I have a well treated room, but the decay time from 100Hz down is still a bit too long. The modes have been dealt with, succcesfully, but the overall decay time at low end could still be better.
I have "free" space at the rear wall, and I would like to find a best way to use that space. Height: 1200mm, Width: 2800mm, Depth: up to 400mm.
So far I have used Porous Absorber Calculator to find best resistivity/air gap combination to use with simple Porous Absorber. Seems to me like the best combination in my case (below 100Hz) is to fill all of the space using something with very low resistivity. Correct?
But since I know so little about different bass trap designs, I´d like to ask if there is better way to use that given space than using Porous absorber? Like I said, I only need to focus below 100Hz, above that I think the room is as good as it gets.