have you calibrated with an SPL meter to make sure it is not running to hot?

I had a rattle on my first ep 500 and axiom sent me a new driver, a new amp, and finally sent me a whole new sub.

You may find some helpful info in these links


http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=192062&fpart=1

http://www.axiomaudio.com/boards/ubbthreads.php?ubb=showflat&Number=181851&fpart=1


-David