You can make a patch to to the cone using a thin glue and a layer of fiberglass mesh tape similar to a drywall joint tape. An epoxy as Bill suggest and a small patch on either side would be best. Try to keep the patch small because you dont want a weight build up that will change your drivers specs. Anything you do to repair it will of course change the sound. The question is can you hear the change or is it worth a recone. If you have a 1/2 hour it's worth a try.

Bill

Yeah, that's a good point. A few others have also reccomended this.

Max linear SPL is that of the graph shown, 30Hz and above in Hornresp shows excursion requirements are minimal, but in the 20-30Hz region, excursion requirements shoot up greatly hence limiting maximum output. A longer horn length will remedy this, at the cost of size :'( I'm going to try and see what I can do though, maybe I can fit in some extra length.

My walls are strong, sort of :P One of the walls has a massive crack in it, many multiple and deep cracks actually which got there when a new door was put in some 40 odd years ago by another owner, seems like the guy didn't quite get the handle of cutting a hole in the wall, haha. My 18" vented box sub has also added to the cracks :P Not to mention the ceiling actually is pulled away from one wall completely, and my sub has extended that down half of another wall too :P We'll see what happens anyway, its held up the last one and a half years I've owned the 18" sub. Another good year of 120db's should bring it down, haha.

Cheers
Adrian