Now that I think about it, downward-angled woofers have been around a
long time for PA gear, usually referred to as a "scoop" design.
For example...
Link Removed
But I'm a bit confused because I've usually seen "scoop" mean
a front-firing driver that is horn-loaded to the rear...
aha, this page helps a bit:
http://colomar.com/Shavano/subs.html
... see the section on horn-loaded designs and variants, notably the
"angled scoop" variant.
Oddly, the Schroeder (and presumably the earlier Tech designs) doesn't quite seem to be any of these. The angled scoop seems to require a fairly large opening from the rear of the cab into the back of the scoop area. If you open the back panel of a Schroeder you'll find only two ports there. It seems to be sort of a hybrid of angled-scoop and conventional ported cab design, but the interior volume is a bit smallish for a conventional 2x12 port design (it seems to be about 3800 cubic inches on the 1212, a little over 2 cubic feet) and the scoop area is pretty small. I don't really get it, but the ports firing into the small scoop area just seems to work.
Aw heck, I'm just talking out my ass here.