House Wiring Defect?

Do not forget that house panels are 208-230 volt in the USA anyway and you should take your outlets from the same side of the panel. Typically break 1 is one side of the panel and breaker 2 is the other side so when you power your room you should use breakers that are all even or all odd. This can also increase the differace in ground protentials. Try stay away from the side your refrigerator or any moter is connected to. Also ask your elecrican if you panel is balanced, meaning even power distribution from side to side, this is not the same as balanced power so do not confuse the two. Some audio equipment is more sensitive than others to this problem.

Single phase
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Please be aware that most "microphone" cables (i.e. from a "music store") are incorrectly wired -- they often have pin 1 tied to pin 0, which is the shell. As clever as this is for electrocuting musicians, we still have musicians so the premise isn't working well...

Seriously, you'll have to open both ends and determine if the wiring is 1==1, 2==2 and 3==3, with nothing else.

You also might try disconnecting EVERYTHING, then start from the sub and speakers BACKWARD, listening to each step.

And of course IF you have TV cable connected to anything then that's very probably your culprit.

Regards,
Barry

Please be aware that most "microphone" cables (i.e. from a "music store" are incorrectly wired -- they often have pin 1 tied to pin 0, which is the shell. as good as this is for electrocuting musicians, we still have musicians so the premise isn't working well... Seriously, you'll have to open both ends and determine if the wirinfg is 1==1, 2==2 and 3==3 , with nothing else.

You also might try disconnecting EVERYTHING, then start fro thje sub and speakers BACKWARD, listening to each step.
And of course IF you have TV cable connected to anything then that's very probably your culprit.

Regards,
Barry

Thanks Barry, yep I took apart my Kimber PBJ's overcomplicated Switchcraft XLRs to check their wiring before I figured out everything needed to be on the same outlet.

For the record, although the outlets are wired with three core wire, the electrician here at this circa 1930's rental says it's two core down to the box. One of the two outlets in this thread is a new one for the window A/C unit. The electrician says he used half the 240. From what I've read here all the 120 circuits are developed that way. My guess is these two outlets have different ground schemes.