If it were me, I would make it simple and get a bunch of 15" sealed subs. The reason is they would be a lot easier to work with than gigantic ported enclosures. 18" drivers necessarily make the enclosure so heavy as well even in a sealed box. 15"s are the sweet spot; lots of output and low resonant frequency yet the boxes can be handled by a single person.\n\nI would look into maybe getting four of these puppies. Stereo Integrity has the HST-15s as well, but those will weigh an absolute ton and you will need to build support braces just for the motor, so I would do your back a favor and skip the HSTs. You could drive a quad crew of those SQL drivers with a couple of these Crown amps and then make a DSP filter in the amp to shelf the mid-bass response until you get a flat response down to 15H in-room.\n\nAlternately, this new Dayton driver looks like another good solution for chasing after low frequencies in a sealed 15" box.\n\nOne driver I have long had my eye on for a project like this is the Dayton RS HF 15". It won't move as much air as the other two but it is very linear and should give you a nice flat response in the appropriatly sized enclosure. It has beautifully low Le as well as a nice low Fs. It doesn't need a ton of power. A bunch of those in sealed enclosures placed around the room should net a nicely flat response. Power those with a rack of these amps.\n\nOne thing that would make your target response much easier to achieve in a system like this is something with Dirac's Bass Control software, which allows it to independently calibrate each sub for your overall target response. However, it's easy enough to do manually as well.\n\nShady is they're a way to shelf filter on those crowns? I own 2 of them the XTI 6002. Was originally going to use them on the theater room with my RBH passive subs but you can't set the filters pass 20 Hz. \n\n No problem I thought just use a shelf filter like on the Behringer but they don't or I can't seem to find it. Unless I'm doing it wrong.