Any ideas why my EP500 sub would be rattling or vibration noise on a less then 50% setting just seems to have started doing it this last month? I thought it was a picture on the wall at first. Anyone have this issue?
Definitely have to isolate the rattle directly to the sub vs. anything else in the room. For the longest time i kept thinking it was our sub (in our old house) and it turned out to be the door on the electrical panel in the corner next to the sub.
If it really is an internal sound, you could unplug the sub, unscrew the back panel plate and take a look at any of the internal screws or wire leads to the driver (assuming you are comfortable with such activities).
Otherwise, beyond that, probably should consult with Axiom folk and possibly need to return it.