These traps will go (almost) floor to ceiling in the corners I can see (front) from my monitoring position. There will be 2 on each sidewall/ceiling corner - 8 feet long (total wall length is 13 feet). There will be one that is 4 feet long top center of the front wall.
There will be fabric stretched across the entire front and around the sides of the 3/4 plywood. The outside 1/4 will then be attached to that so I can screw it to the wall. The pinkish area is the solid top/bottom, but you can use the front line of that to imagine the line of fabric (except the fabric will cover the front of the 3/4 plywood).
The screws are 16" from the corner, and the 1/4 panel across the front is 20" wide. I can play with this dimension a bit, move the screws to 18" or so - as you can see I will have to trim the corners of the 15" rockwool at this dimension.
My thinking is that the 1/4 ply panel will act as a low freq. absorber, or transfer the energy, and the rockwool behind it will dampen it. I am also thinking that using a hard surface here would help to not over do the broadband (of which there will be (8) 2'x4' panels around the room).
I am not certain if the 1/4 ply is too much. Should I look for a thinner material? I'll need at least (4) 4'x8' sheets as is. I think these will look really good installed, I just want to make sure they are functional, too.
Someone told me I could further 'tune' these by cutting holes in the panel. Any truth to that? I know you can increase absorption on a broadband panel by cutting holes in the side of the frame. But this guy was talking bass traps. He had equations he said he could use to determine how much % of surface area should be removed to affect a particular freq. He said it was based on the Helmholz resonator... but I thought that had to have a tube with volume involved?
Thanks for any feedback.