The nubers show that it is not ideal for 4th order use, however I have four lvl 5 m3 15's in a 4th and it is nasty, plays lows (25hz) and does a 162.6 @ 51hz. I was worried that I chose the wrong enclosure for my subs but once I got the sealed side and port area correct I stood corrected. BTW, Thank you again Jeff for getting me on the right path!
nice! I saw the thread that you made about it.. wasn't sure if you went through with it or not.. what size or ratio did you end up going with for the sealed and ported sides? do you have any videos?
I went with a 2.2:1 ratio but thats not really important. What I have learned is to get the sealed side correct ( start big and shrink from there) and get the port correct. Lot's of testing , removing subs bla bla bla. My sealed side is right around 2 cubes per sub