Flat Diffussors

Hi, my recording room looks like this at them moment. http://www.coldgroundstudio.de/images/s ... rd1000.jpg http://www.coldgroundstudio.de/images/s ... ed1000.jpg Reverberation time is nealy 0.4s over the whole spektrum with just a little peak at 150 Hz. Something to improve but not now. My question for now is an other. You see the 4 broadband absorbers on the wall from floor to ceiling. The rooms sounds ok for rehearsing, recording of guitars and vocals. But for drums it is too dry. My idea was to build "something" that can be mounted temporarely in front of the absorbers. Just like folding varibale acoustic designs with a hat diffuse (or flat) surface and absorbing surface. Now to the "something": I though on somethink like RGPs flat fusor (http://www.rpginc.com/products/flatffusor/index.htm). Some plates of ply wood with holes in it. That shall reduce the absorbtion of the absorbers and give some diffussion without the need to actually build diffors on the ply wood side. What do you think?

another option is to use MLS (or other numeric) sequences to space some 3/4" plywood strips (or simply cut out the openings in a sheet and then it's easy to put up or take down as needed.

Hi, nice idea! 19mm is really think. I think MDF will be cheaper then. What I'm sill missing is the theoretical background of (for example) RPGs flatfusor or aother binary diffusors. I mean the full mathematical background to calculate them. They are not mentioned in the books, at least I have (4). I studied electrical engineering (although I'm working as a software developer), so mathematic is not the problem. But I didn't find something until now. I'll keep searching. But if someone knows some links ...