I've been meaning to do an X months later update on this build, so I might as well do it now. lilmike's comments about bracing in the F-20 thread reminded me I'm a bit late in doing this.
I am currently at 18 months with the sub, give or take a few days. Learned a few things since the build about what to do and not do when it comes to building these, and I wanted to share my thoughts about it.
First, I am upgrading this unit from "bracing optional" to "bracing strongly
recommended." I have not had any problems with this bad boy due to the lack of bracing (and I've not heard of the other builders having any problems), but I do know it is not the sub it could be were it completely braced. The driver baffle does flex ever so slightly at high SPL. We don't want that if we are running this box at full blast consistently, thus my change in the recommendation. You can get by without it, mine is proof of that, but it's something I'd like potential builders to start considering. It won't give you its full potential without bracing.
Second, before you build one of these, take the factory gaskets off the SDX drivers first. Those gaskets promote leaks, as I found out the hard way. We don't want that. Best to use the duct seal putty alone.
That's it for now. It's still a low end monster in my home theater... I've lost a few more pieces of stone off the wall by the fireplace since I first fired it up
To date, best SPL with both horns in use is still 124dB at listening position. I won't let them exceed that. I like having the ceiling above
my head, thank you very much.