Hmm, building this inner wall seems very labor intensive and expensive when you do the math. I can get a lot of bass traps for the money.
The following is a 360 x 480 x 237 cm (11.8' x 15.7' x 7.8' ) room, pretty standard room size around here. If I use this for mixing and recording,
is that bass trap placement adequate? The depicted bass traps are 150 x 75 x 10 xm (60" x 30" x 4"), one in each corner, 2 in the middle of the long walls and one angled one above the mixing desk.
More pictures from various angles here:
ImageShack -