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Hum from Subwoofers

I've noticed a hum when the volume of my system is turned up (with nothing playing).  The hum is silent when I unplug the subs (a pair of REL Storm III's).  I tried using cheater plugs on the subs, but it makes no difference.  Hum is present with the ground lifted (with cheater plugs), and present with the ground connected (without cheater plugs).  Again, when I unplug the subs, the hum goes away.
The subs are plugged directly into the wall outlets, and the rest of my system is plugged in to an Audio Magic Mini Ref conditioner (no unused outlets left on the condioner).
Any thoughts on how to correct this problem?  
In advance, thanks for your input!
Louis
louisl
erik_squires
16,015 posts
 
The question is if the hum is proportional to your volume control. If it is, then the hum is at least from there. It may be that your speakers don't have enough output at 60 Hz without the subs. 

Turn everything off and remove from the power everything but pre-amp and sub. Still happen? 

Best,

E
erik_squires
16,015 posts
 
One forgotten source of ground loops is external coaxial cables, like to your Cable TV or Satellite dish. Make sure you unplug those too. They make inexpensive GL isolators but they depend on your devices. 

Best,

E
louisl OP
183 posts
 
Thanks for the responses Eric.  1.  The speakers are full range (Legacy Focus SE's), and yes the hum is proportional to the volume.  So are you saying the hum is coming from the sources?  I get hum from both my to TT & my CDP.
 2.  No TV in the room.
noromance's avatar
noromance
9,732 posts
 
Sounds like your sources are picking up stray mains hum, possibly from transformers or motors that are being amplified by the subs. I'd try running everything without the conditioner. Plug it out and move it away.

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