"When I posted that design a few pages back with the SEOS-18, Tux said there probably wouldn't be much reason to do that over a Fusion-12."
yeah...that's pretty much all that one is. just has the "sub" built into the same cabinet for mostly aesthetic purposes. separating it out probably makes more performance sense, but there is something about the aesthetic of the "all in one" cab that has some sort of appeal. can't really explain it...but it does.
"Or it the goal is just a celebration of testosterone, instead go for the whole kabuki thing and put drivers wherever and however and make it big and loud.!"
that certainly seems like the spirit of this project.
a big cab with four woofers crossed in around 700hz might work ok if one sits far enough back. kind of like the jbl theater cabs...but with twice as many woofers!
kind of like the one in this pic on the left, but a smaller horn.
the benefit would be that with the right 15" driver, sensitivity would be VERY high and in a corner/up against a wall, would probably have over 100db 1w1m sensitivity down into the 20's, so even with a typical AVR, the thing would have crushing output. red line is the 21sw115 for comparison.
jbl theater cabs for comparison.
alternatively the top woofer could be used for an octave or so below (e.g. 350-700hz or so) with the other woofers rolling in underneath thus providing for downward sloping overall frequency response and eliminating two problems: 1 the giant choke of a very low crossover on the woofers and 2 the vertical spacing to the center of the four woofers.
if the bass is a little rich, tone control could be used to back it down relative to the mid/top without losing the sensitivity. most avr's have at least some sort of 'bass' tone control. hhmmm...