[omholt]

I have two questions:

1. Besides from 4 Tri-Traps and 2 244s I have some DIY absorbers made with rockwool (2,95 and 3.9 inches thick) and I feel that I've to be really careful using them in quantity, they can easily overdampen the highs and leave the music lifeless. How can I make them into mebrane/panel absorbers? Is it enough to simply cover the rockwool with some plastic?

2. What's normally the best treatment for the ceiling? I was initally thinking buying some diffusors, but read someone saying that using diffusors in the celing will be detrimental to the image. Any thoughts?

Here's some pictures of my room. I also use diffusors on the back wall. The speakers you see in front are really my surround speakers. Normally I've larger front speakers.

 

[bpape]

Diffusion can work very well IMO on the ceiling. Yours is different enough to already avoid many of the ceiling issues that would require absorption.

On the other hand, the next to last picture you embedded shows a high, acute angle ceiling area which can lead to a lot of horn effect and bass buildup. If possible, doing a couple of thicker panels up there parallel to the floor and covering the angle would be a benefit IMO.

 

[omholt]

Thanks.
I find this a bit difficult choosing. On the sidewalls I can switch between absorbers and diffusors, but that's not the easy with the ceiling. I think it was Arthur Noxon that said diffusors on the ceiling destroys the image.

Perhaps a combination of some 242s/244s (where the ceiling meets the wall) and D1s filled with fiber glass in the first reflection area would be the way to go?

 

[bpape]

That would be my choice.