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Hi guys,

This is my first post here and am really do so because I am desperate and need to get a few other opinions. I run a small overdub recording studio from my home and when I moved to my current spot, the amount of EMI picked up in voice-coil (magnetic field) microphones and electric instruments is at a level that I am unable to track anything. I have done extensive testing in the house myself, have had my electrician out, borrowed an ammeter to take reading over a span of 2 weeks, and had the Electrical company out, with no resolve. Let me give you the story (I apologize in advance for the novel).

To preface, I am not an electrician, I am an audio engineer/musician so I have a very basic understanding of this stuff but luckily have a good friend who's a master electrician.

For all tests, I analyzed my gear both using power from the wall and as well as a mobile rig running off of a battery powered laptop and a USB powered recording interface, so no power from the house was being used at all. The latter was the rig I used to conduct most of my testing as I could move around the house easily.

First thing I did was shut off all circuits on the panel, aside from the Mains. When turning off large appliances, (dryer, fridge, etc.) the buzz/noise diminished somewhat, but very little. When I turned off the Mains, the sound remained. This rings true if I have the recording rig in my studio, the living room, or in the basement 2ft. from the panel. I called my electrician and he checked grounding in the outlets, no issues, I am getting good clean current, and for a house built in 1910, we are lucky enough to have a place that was rewired by the previous owner; so good solid wiring and grounding wire. He also checked all connections in the panel and everything it well connected and tight. My electrician is convinced that there is backfeed from a neighbour downstream causing all of this nonsense.

Here comes the ammeter adventure. While we had the Mains off, we checked the ground wires. One goes to the telecommunication box and the other to the copper water main. The ground to the tele box read 0.0-0.3 amps if it read anything at all but the water bond read over 3A. It was also fluctuating. We turned the Mains back on and the reading rose but not by a whole lot. He left the ammeter with me and over the next 2 weeks, at varying times during the day, I got consistent readings at 2.5A, 6-7A, 9.5A, and a spike at over 16A! The most consistent reading I had was in the 3A range.

So yesterday I called the service company and they tested their lines and stated that everything was ok on their end. The dude was somewhat sympathetic to my situation and seemed to want to help, although he immediately scoffed at the notion that it could be a backfeed problem. Damn linesmen. Anyway, he ended up replace the hot, neutral, & ground service lines from the secondary, in an effort to eliminate all possibilities. While he was doing this, I setup my mobile, battery powered recording rig to see if there was any change once the lines were reconnected. The moment he dropped the lines from my home, the infernal buzz disappeared. It was like the heavens had opened and for 30 minutes I was in bliss. As soon as the new lines were connected and power returned to the home, the buzz returned.

This linesman inspected our meter, an older analog meter on an old school circular meter base. He is convinced that the meter base is the problem and needs to be replaced with a new one. While he removed the analog meter to show me how old the base was, the buzz in my recording signal diminished, enough that I noticed from a few feet away. When he put the analog meter back in, I got more noise. So he grabbed a new digital one and put it in the base, less noise than the analog one, but still unacceptable. The linesman left, told me that a dude will come by in a couple of days with some wizard laser on his truck to analyze the lines and that I'll get an email.

I called my electrician, and he is still convinced it is backfeed. His next test, once the ground thaws, is to dig a hole, pull the water bond and test that ground line to a ground plate to see if we are receiving this mess through the city's water system or a neighbour.

So, until the ground here in Canada thaws, I will continue living with the insufferable buzz. In the meantime, I thought I'd check in with the internet and see what you all have to offer for advice/expertise. Thanks in advance for any & all help.

Scott
 

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TL;DR...

Audio dudes have posted similar blues many, many times here in the past.

Troll through the back-threads. Their stuff will pop right up.

You're extremely unlikely to be getting EMI through the air... you're not sitting right under power lines, are you? No HAM radio operator right next door...?

It's going to be found in your set-up.

The usual drill is for extreme isolation from 'dirty power.'

( Isolation transformers, a sweet grounding connection, and all the rest. )
 

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Thanks for posting on ElectricianTalk.com. However, working with electricity and electrical systems can be unsafe if not done by a professional licensed electrician. The moderators of this site would like to advise you to contact a professional electrician in your area.

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