Shouldn't have to call Axiom, many of us have had this issue, if it is the same thing.
Just unplug the power cable from the wall, OR turn the power switch off/on. This is a know problem that many of us have had in the past with EP subs. I was upstairs once and heard a low sound like you describe. I walked all over the house and found it was my EP600 emmiting a very lowwww random thumping sound, almost like thunder in the instance.
Anyway, that should fix your problem. I think over time they build up some electronic charge or something...
I'm suprised MarKS does not remember this, he created this graphic.
