The Bagend, Black hole and subwoofer trick (which I forgot to mention he said to try both in and out of phase) all seam to be doing the same sort of thing.
I'll try the sub trick since I have an extra sub around. If that helps, I'll consider the other technologies. I think an acoustic fix like a Helmholtz is still likely the best solution.
I'll try the sub trick since I have an extra sub around. If that helps, I'll consider the other technologies. I think an acoustic fix like a Helmholtz is still likely the best solution.