I have 4 CVR 12's in the back of a 4 door blazer. Two are firing back and two firing on the sides. They are hooked up to a jbl bp1200.1. they just do not sound that great. Is this because of the box, space, could one be busted? All four inputs are being used. what would help
make sure they're wired so each sub is getting 300 watts. this sounds like it may be the box.. yeah. if it's sealed, each sub needs about 1.5cu ft. ported, wach needs about 2cu ft. you could also try rebuilding the box and going with an isobaric clamshell enclosure if space is a concern.. it won't be as lout as 4 sealed 12s, but it'll save space and work well.