Re: Concrete SPL build
Why are you going with a 3" thickness, with a good portland cement you should be able to pour a VERY dense rigid enclosure and not have to go beyond 1.5" in thickness also portland has a very tight structure to it after it has set-up, it's usaually mixed with sand to change it's consistency but I would use as little of that as possible.
electrical: Optima yellow top X 2 big 3 in monster OFC 1/0g high output alt by maniac electrics
HU: JVC AVX-77 touch screen
Front stage: RE XXX 6.5" comps
front stage amp: Rockford T600.2
subs: 1 Sundown ZV4 12"
sub amp: Rockford T2500.1BDCP
Enclosure: ported (by JayDubb757 )