DIY QRD Diffusers (1 Viewer)

[Dave Milne]

I'm just completing my dedicated theater (photos coming soon). Does anyone have plans (or just the equations) to build a quadratic residue diffuser, such as those sold by RPG? I'm envisioning something about 3'x3', in solid walnut, that hangs on the wall.
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[Mac F]

I had considered a similar project once, but have never gotten around to it. I believe the formulas were in Alton Everest's book, "handbook of Acoustics". Mine was the second edition, I believe the 3rd edition is out now. The book gave formulas for a 1 dimensional refractor, meaning a sound wave hitting it will scatter horizontally or vertically, but not both. RPG makes some as 2 dimensional, which would scatter sound both directions. My guess is this may be done by turning the specs 90 degrees and add it to the elevations of the other one. Even better, maybe someone else knows exactly how this is done.