I want to get a 1x15 cab to add low-end heft to my rig. I'll probably get an Avatar, because they're built solidly, and I don't really care about the crossover and tweeter. I'm debating what speaker to put in it. I have an old 500 watt Carvin PS15C that's basically unused and has been collecting dust for years. I've been trying to use WinISD to try to determine if it would work well. Problems I'm having: I don't know the exact inner dimensions of the box--can anyone help me out? When I put in a square port of about the dimensions I think the Avatar box is (~23" x 1"), it says "too short" under port length. Am I doing something wrong? Does anybody have any general advice about this? Is this speaker worth it, or should I get an Eminence? Any input on this would be appreciated.