60 Hz Hum from Powered Sub

If you added a new electrical device, it could be anything from a cooktop to a heater. This device could be causing a DC on mains issue which causes  the transformer to buzz. So you need to isolate the noise. If the driver is making the noise, it is most likely a ground issue somewhere, aging components or aging sub cable with deteriorating connector. If the transformer is buzzing, it is most likely the DC on mains issue. Emotiva makes a specialty filter that works if that is the issue. If the sub is old, its not worth fixing unless it has a special connection for some reason.  

Spacecadet3;
moving it around to rule out ground loops is nonsensical.  ground loops will occur whenever there are two different paths to ground. By moving it you guaranty a different path!

Every single solitary component in your sonic chain must b grounded to the same circuit, preferably to the same outlet.  The best way i know to achieve this is to have a 20A outlet, and buy the biggest, heaviest duty outlet strip you can get and plug everything into that.
if you need to daisy-=chain them do so. But use heavy strips with heavy cables and preferably upgraded or even hospital plugs.  Why? solid, high current contacts.  the $15 is well spent.

However, you said it "developed" a hum. You didn't say "i rearranged stuff and suddenly there was a hum". Be clear which was it?  if it just developed with no changes then indeed you likely have a problem in the woofer and it requires service. A loose ground, bad connection, or failing capacity or among myriad other reasons....

I doubt its a big deal, but qualified labor is not cheap.

Good luck, noise issues can be buggers.
G

It definitely "developed" the hum. It has been in the same location for about 6 months and it's just begun making the noice in the past 2-3 weeks. From all of the comments collectively, it would appear that the amp has caps that are failing. I'm not sure I have the time or interest to mess with it. It will probably be retired.

Thanks to all of you for the great responses!

G

The 2 prongs on a plug, one is hot the other neutral, aka utility ground. The third is earth ground and is redundant.

My first thought when reading this was to not respond. But then after thinking about it for awhile I would be remiss if I did not.

/ /

NEC article 100 definitions.

Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

Grounded Conductor. A system or circuit conductor that is intentionally grounded.

Informational note: Although an equipment grounded conductor is grounded, it is not considered a grounded conductor.

Grounding Conductor, Equipment (ECG). A conductive path(s) that is part of an effective ground-fault current path and connects normally non-current carrying metal parts of equipment together and to the system grounded conductor or to the grounding electrode conductor, or both.

The Grounded Conductor (neutral) and an EGC, (Equipment Grounding Conductor) are not interchangeable with with one another. The two serve entirely different functions.

The 2 prongs on a plug, one is hot the other neutral, aka utility ground. The third is earth ground and is redundant.

"utility ground" ???

"The third is earth ground and is redundant." No it is not a redundant ground ... It is an EGC as defined by the code...

The neutral conductor is a current carrying conductor and should never be used as a safety EGC.

A circuit neutral conductor is only grounded if it is connected to the electrical service Grounded Conductor.

Open Neutral:

An open neutral is where the neutral connection to the electrical service Grounded Conductor is broken, open.

An energized open neutral is dangerous and can be an electrical shock hazard or worse lead to death.

An energized open neutral? Where there is a connected load on a circuit (branch circuit wiring) and the neutral connection is broken, open, upstream (source end) from the connected load.

There will be a 120V difference of potential between the two broken conductors of the neutral. 120V as well from the load side open neutral to any grounded object.

As you can see it would be a bad idea to use a current carrying neutral conductor also as an EGC connected to the EGC ground terminal screw on a wall outlet or directly to the chassis of audio equipment.

( Existing 2 wire branch circuit wiring, (no EGC), 2 wire duplex receptacle is replaced with a 2 pole grounding type duplex receptacle outlet).

.