Originally Posted by Quill
So now we hauled this beast to a whole new home (80
miles away), and hooked it up to a completely different system. We did not re-use a single cable, not even the sub power cord.
The result: identical hum.
I hate it when hums follow me.
And once again, it goes away as soon as we unplug the TV source. First was cable, second home is on satellite.
Any ideas? I'm at my wit's end....
I have and use two different isolators. One did a bang up job that I feel comfortable referring.I used this isolator with no success.
It's a well reviewed isolator but I can't recommend it as in our case, my expected results were not met. That doesn't not mean the isolator didn't work, it's just means the isolator didn't correct our particular ground loop problem but the much more expensive box did as the actual offending cables, themselves, were isolated.
edit - also, this sub came with a 2 prong cord...shouldn't a sub have a grounding plug?
It's a bit of a foreign concept but now equipment is being made with the neutral return being the ground as that's what a neutral return is. Hence why the plug is polarized. If there's a short, the extra amperage and potential gets shunted over to the neutral return. Even as a general contractor it took a while for me to get use to the idea of a neutral return being used as a ground.
Have you tried disconnecting the subwoofer cable? Pretty much, even if connected by a common metal shelf or pole stand, any attached appliance can introduce it's own ground loop problem. If when disconnecting the subwoofer "in," the hum goes away, then you need to put an isolator between the subwoofer cable and the subwoofer's "in" connection.
If you can, use a multimeter and when no signal is being sent to the subwoofer by the AVR (AVR turned on), measure the output of the subwoofer cable. The signal should measure zero to almost zero. Done in the fashion I recommend, the isolator in place, both supply lines measure 0.1mV.