Had to run to dinner but thought I'd get a pic up before I forgot and got onto something else. This is an N23 QRD diffuser. It still needs fins and assembly. Its supposed to diffuse down to 450Hz and scatter down to 230Hz IIRC. It was calculated with the QRDude software available online.

The deepest well is 9 11/16" and it is just over 6' wide and 37" tall. They are styrofoam blocks salvaged from a construction site garbage pile. One mans trash....

I plan on using it on the front wall behind the screen. My hope is it will help eliminate the center channel boxiness/echo (still havent pinned that down, as some material has no issue) mid bass response slightly and most importantly, make it sound like there is no front wall behind the screen. I've always tried to connect people's descriptions of the qrd's spacious effect with a use that can apply to our visual perception. One day in the shower, where my aha moments happen, I decided behind the screen might make the image sound like it has deepth. Kind of like a theatrical stage more than a flat screen. See how it works I guess. Always wanted to make one.