I know, I am using it now. Based on past measurements I know I get 4-5hz. I am wondering if I should get another clone or a different amp for these. The boxes are big for two so it acts like a IB with little power needed to reach x-max at 5hz. I built the boxes big enough to port these to 11.5hz. Now according to sims I won't lose 6hz but gain everything above but I am not sure reality is the same.
I mix resonant and sealed SI 18s and it is tricky. I have a suckout at the tune of my ported subs (a pair of full-size marties with ~16.5hz tune). I attributed that to them being 180 phase with my four other sealed 18s approaching the tune frequency. When I run REW sweeps, I get a steady rise in the single digits, then a step cut in the teens centered at 16.5, and then back up again. I haven't done enough sweeps with separate sub groups to be sure, but the out-of-phase made some sense. I would be well aware of this if you're trying to mix sealed and ported. It still worked well for me (I high-pass the martys at IIRC 20 hz 3rd order which yields a net gain over 0-120, but I'm not really pulling the max out of each and every component that way) Unless you have some fancy DSP trickery to do a frequency-based delay and get everything to align. (And if you do, I'd like to know how you do it. )