2. tech-talk
  3. 1225969274

House Wiring Defect?

Recently I introduced a new power amp connected to my preamp with XLR cables. The pre and power amps were plugged into different outlets in the same room which produced a pretty loud hum from both speakers with the preamp on or off and the power amp on. After the inital freak out and a check of all connections I realized one fix was to power the pre and power amps from the same outlet. This restored quiet operation using either outlet. The question is, does this indicate a house wiring defect or nothing to worry about?
rockvirgo
eldartford
4,262 posts
 
Not a problem. Only audio equipment is sensitive to slightly different ground potentials.
cford
66 posts
 
It might mean that the hot and neutral may be flipped one 1 of the outlets, so I would check it.
zapper
68 posts
 
It seems the 2 outlets were on different phases of you house electric, which induces a hum. With them on the same outlet/phase, hum is gone, makes sense.
You house is probably fine. You can use a 3-light tester to see if the wires are reversed on either outlet.
consttraveler
250 posts
 
Remember to turn off (at the breaker) the house power before you take the outlet cover off to inspect the ground and +,-.

I know it is semi insulting to write the above, but having grabbed 220 once myself (and 110 more than once), it is meant in the kindest way.

Best regards,

Dave
rodman99999
6,126 posts
 
Cford has it right. Be certain that the black wire(hot) is connected to the copper screw of the outlet, and the white wire(neutral) to the nickel screw. You might even check the breaker box connections, while turning off the power, as Dave suggested. You should only see black wires connected to the breakers, and whites to the neutral buss(could be reversed there instead of at the outlet).
More to discover