It is not normal for any rattles to be occuring, unless you have a loose screw or the port is rattling.
Are you sure your not running the sub/receiver levels (volulme) to HOT? Have you calibrated the levels to match your other speakers? Many people think they have to crank up these levels.
With my receiver SUB level at about -1dB, my volume on the sub is very very low, like around 6-7 o'clock. With these settings I am at about 75dB SPL from the listening position using the Radio Shack SPL meter.
I use a trim of FLAT and Bypass on the crossover.
Randy
ps: if you've had the sub this long, have you called Axiom?
Also, how do you have the other knobs set on the back of the sub?
