Tube Amp buzz due to dirty electricity in my house

[Songful]

Hello,
I have a loud buzz when I use my Vox AC15C1, but only when played in my house. I have been told by an electrician that we have "dirty electricity" in our house due to the distance from the nearest power relay sub-station (or something like that). I live in a somewhat mountainous region of the Hudson Valley in New York State. I have tried using various power conditioner products, but nothing worked, except for one strange thing. I had a large Fender Passport PA system, and when it was plugged into the same outlet as the AC15C1, it significantly reduced the buzz in the amp. I have since sold the PA because it was broken, but I am wondering if another appliance would suffice to do the job. I have tried plugging several other appliances into the outlet to see if I can replicate the results, such as: a microwave; other amps; and light fixtures. The odd thing is that the old PA didn't need to even be turned on for it to have the positive impact of reducing the buzz in the amp.
Does anyone know what component in the PA could have created this result? I am shopping for a new PA, and it would be great to have the side benefit of a quieter amp.
thanks

[sluckey]

I had a large Fender Passport PA system, and when it was plugged into the same outlet as the AC15C1, it significantly reduced the buzz in the amp.... The odd thing is that the old PA didn't need to even be turned on for it to have the positive impact of reducing the buzz in the amp

The .047µF line filter cap on the ground switch is the most likely component in the old pa that could reduce the line noise/buzz. I suggest you get two .047µF Class Y caps. Connect one between AC line(black wire) and AC ground (green wire) and the other between AC neutral (white wire) and AC Ground. The ideal place to physically locate these caps would be directly on the IEC power socket if the amp has one.

You can use regular coupling caps (.047@630V) to test, but you should use Class Y caps for a permanent solution.

[R.G.]

Condolences on the dirty electricity. It happens sometimes. There is a bar/venue in Austin where (I've been told) the steel beam structure under the stage causes hum in even well made, properly wired amps and other equipment.

Sluckey's suggestions are well worth a try.

A slam-dunk solution, which suffers only from being heavy and mildly expensive is a constant-voltage transformer, also called a ferroresonant transformer. These can be had used from ebay for $50-$300 in sizes that will run an amp or PA, etc. A CV transformer operates on having a HUGE resonant circuit running at line frequency and letting the secondaries sip current from the resonance. The resonance amounts to a very high power, very high attenuation filter that passes line frequency and nearly nothing else. CVs >regulate< the AC power too, so you get pasteurized, homogenized, bug free AC on the output.

The weight makes shipping a headache, all right. But it's a solution for tough cases.