Glenn,
Thanks for your fast reply
gullfo wrote:on the slats, 20mm-40mm thick should be fine depending on your calculations. width and spacing, lot's of time randomly arranged and spaced to break things up visually as well as possibly increasing the diffusion aspects.
mmm.....ok...I haven't done ANY calculations whatsoever, except on the angle of the slat wall. I just downloaded John's "components.skp" file and read his Recording Manual. From that I had the impression that the 100mm, 50mm, 25mm slats width, and 2,5mm, 5mm and 10mm slots gap was sort of a "universal set" for broadband slat walls. The only doubt I had was about the sequence or order of the slats and slots.
Isn't this so?
gullfo wrote:no plastic for the slats. just some loose cloth behind the slats. leave air space from the slats to the insulation. you can lightly fill the cavity with pink insulation.
Ok, so the insulation can be glued on the wall side then. Cool

I was asking because on John's "components.skp" file, the insulation is next to the slats, whereas on the Rec Manual, as shown above, the insulation is not against the slats. It probably doesn't matter, but given my knowledge in acoustics (=none) I prefer to check things
gullfo wrote:not sure what you mean by the central slat. if you mean the total depth of the cavity being 26cm at a given point, if that is the depth required it should be fine.
Sorry for being unclear...by central slat, I mean the slat wall you suggested I build between the soffits. This wall is not angled, so the cavity will have the same depth all along its width. As I'm going to build the frame that will support it, I wanted to know if 26cm deep is ok...
gullfo wrote:on the modes, let's assume a rectangular room, the positions of the nodes/anti-nodes will likely be consistently located. 1/2, 1/3, 1/4, 1/6, 1/8 of your room dimension on each plane (ceiling, wall, floor). in your calculator you see a dimension and frequency based on mode (1st, 2nd, 3rd...). the first 3 modes on each plane should be targeted first using broadband treatments.
mmm, let me see if I get this right:
The Calculator says:
Height: 74, 147 and 221 Hz
Width: 41, 82 and 123 Hz
Length: 31, 62 and 93 Hz
So this means that my clouds, absorbers and slat walls should be tuned to kill all these frequencies (31, 41, 62, 74, 82, 93, 123,147 and 221 Hz) and placed at 1/2, 1/3, 1/4, 1/6, 1/8 of my room dimension on each plane, right?
If that's so, that's basically all the low end, everywhere in the room that I have to save from being cancelled!!
Sorry for this post a little long...
Cheers
Sono