Is it common to blow a sub if its hooked up correcttly. because it will cost me more to get it at a shop but i get a warranty. but if i get it online i cant get 1. so how often does a sub go bad.
Not likely. Unless its Audiobahn, or a Solo... it shouldn't have any problems. Even Audiobahn and Solo's usually have to go through some abuse befor they take a crap.
the many that i have blown in my youth were because of clipped signals. my amps were never powerful enough and i would blast the volume. eventually the sub would die. i have always been an aggressive listener though. maybe you are just into sq. second, if it's not installed and tuned correctly, you could get a spike at high volume and there goes your sub. i would research intensively before installing if you plan on doing it yourself. while it's not rocket science, it helps to be prepared. last, most sub warranties are moot. they often time don't cover blown subs cuz it's not a manufacturer's issue. it's an abusive user's issue. thus, they won't cover it. JL is the only company i know for sure that will, and that might only be through Tweeter/Hifi Buys.