Thanks, Ralph. Perhaps if Huygen's had access to a computer he would have had the same results as Sheerin. I stand by my assertion that his theories on the use of a flat reflector in a folded horn to maximize high frequency passage through the bend is flawed. High frequency sound waves simply don't work the way he postulated. If that doesn't agree with what some folks are teaching then maybe it's time they abandon the chalkboard for a while and spend some time behind a tablesaw. My claims are easy enough to either verify or refute, but with SPL meters, not abstract formulai. And wait 'til you see what I do when it comes to flares.