Originally Posted by 9179mhb
However, now the 12D subwoofer exhibits a background low noise rumble even when all of my HT gear (receiver, etc.) is powered off.
Any help/feedback is appreciated, thanks in advance.
Hi and welcome to the forum.
Definitely contact Aperion, but it also sounds like it could possibly be ground loops too. Not sure if anything changed about the time the hum/rumble started, but the normal suspects would be junk coming in your cable TV line, dimmer controls, or a bad ground connection outside. To troubleshoot, you can try to disconnect cable TV at wall, check; disconnect all inputs to sub, check; then try a ground buster adapter at plug (removes ground from sub's power cord line). Note: The cheater plug should really not be the long term fix, it would only be masking a bigger problem. Good luck.