Humming sub.


I tried to teach it the words to no avail.
Velodyne ULD 15, low hum when powered up, can't hear it when music is playing. It does not vary with volume on the servo controller amp.
Any guesses what it might be? I tried different cables and checked connections.
homer
get a Cheater Plug (unground the sub), if it goes away you have a ground loop problem.
Unplug your Coax from your cable box and see if the hum goes away.
Sounds like ground loop hum, if it is, cheater plugging the entire system is the only way I've ever been able to get rid of it.

FYI, I've run in his configuration for quite some time without any problems. And with absolute silence.
Sometimes if your sub is on the same curcuit as the lights (especially with dimmers or 2 or 3 way switches) it can cause a hum. Turn off the lights and see what happens.