100 hz to 500 hz low mid horn for a 15?

now that i've got hold of these huge horns that play down to 500 hz, i want to make a threeway rig as analog as i can go.  My thought is to use four 15s under each, playing from 100 500 hz which if memory serves me right would require a straight horn? as folded/bandpass horns wont play that high very well.  How big are we talking?  I'd love to use eminence drivers because i'm just starting out in diy and quite frankly cost is gonna be an issue for now, but would like it if i could upgrade later on.  because i'd never use the horns in singles maybe the mouth could be smaller on each but large enough to go down to 100 hz in clusters of four?  thanks guys, open to any thoughts

Very difficult to do a fully horn-loaded rig all-analogue, near impossible in fact, you need some time delay capability to get the different horns to play together perfectly, unless you can make them all the same physical length like in a Martin F2 (the only large-scale horn rig I can think of that got used a lot without any digital processing). So you might as well work from a starting point of using a cheap digital LMS and having the capability to time-align and EQ things.

so you guys are saying run the scoops from below 100 hz as subs right on up? i dont think i'd want to do that, this rig will get used for dj work just as much as for live band work so being able to have clean vocals is important.  Plus i think i like the idea of a pile of center clustered subs anyways so no need for the midbass to go lower than say 100 hz.

Might wanna drop Graeme Goodacre ('Centauri' on here) a PM.
He has a design for 15" that works great from lower than 100 Hz up to around the 500 Hz mark with the right speaker in it.

thanks very much for the replys guys.