2. tech-talk
  3. 177660-4741

Can moving wire location at circuit breaker reduce hum?

The power line going into my music room will oftentimes make the amps’ transformers hum.  I’ve tried many things but have had no luck.  If I take any component that’s humming into a different room run on a different circuit breaker, the hum disappears.

Would swapping out the wires that go into the two separate rooms at the breaker make any difference?  Or is it more likely that one of the outlets on the circuit that goes into my music room is somehow miswired and is causing the hum?  I can unplug everything from the circuit except for my amp and it still hums.

Any suggestions on what I might be able to do short of hiring someone to run a dedicated line?

Thanks,

Mamoru

 

128x128audiodwebe
erik_squires
15,824 posts
 

So, we are talking about a mechanical hum that you can hear or feel at the amp itself, right? OK, that’s a sign of DC on the line.

If you move to another "leg" of the panel it may fix the problem but only if the source of the DC is on another circuit. See if you can locate the source which is often something like LED power supplies or some wall wart somewhere or old dimmer switches. If the problem is on the same circuit as your audio gear then no amount of moving a breaker around will fix it.

If you are sure the source is not on your circuit, then try moving to another leg. Panels alternate legs horizontally, so pick a new location that is off by odd row numbers. 1, 3, 5, 7, etc. If you move horizontally or an even number you will stay on the same leg.

Of course, they also make DC blockers specifically for this purpose.

spenav
416 posts
 

Hi

Looks like you have a pesky one. The way you described it is a little confusing though. Does the hum happen constantly or is it “oftentimes”?  Is the amp the only component humming or are there more?  You talked about “any component that’s humming”, what else is humming?  The fact that moving the amp to another room stops the problem tells you it’s not the amp. Have you tried different outlets in the original room?  To find out if the wiring is at fault, you can try a simple, inexpensive wire tester such as this one: Klein tool RT110 receptacle tester. Moving the wire should be your last result. Good luck. 

gs5556
1,213 posts
 

First make sure there are no motors on that circuit. If not, then use a receptacle tester (the one that plugs in with three lights) and see if it is properly wired. Next step is to check for an unbalanced neutral at that receptacle. Measure both hot and neutral with respect to the ground. Anything more than a few volts on  neutral to ground is not normal. Also check the hot to ground voltage at all other receptacles on that circuit. Any difference is the results of loose wiring, which can cause arcing. Any of the above will make transformers sing.

More to discover