60Hz Contamination in Measurement Mic

[robert]

My Behringer ECM-8000 has decided to pick up 60Hz and assorted harmonics (120, 180, 240Hz, etc.) from out of the air. To ensure I didn't have a piece of malfunctioning AC equipment in the house I put the laptop on battery and turned off all of my breakers, including the main.

This noise is present on both my MXL mic-mate (XLR-USB 44.1Khz converter) and through my Edirol UA1-EX and mixing board.

I have checked the XLR cable (mic-mate doesn't need one), the mixing board, the USB cable, and even made sure the mic's XLR ground pin was grounded to the mic case (good).

The mic does pick up sound and just to test, I ran pink noise out of the stereo and ended up with a pretty standard in-room pink noise with 60Hz and harmonic spikes protruding. I have a not-so-pretty TrueRTA sweep of it, but it isn't really required for this problem.

I am just about ready to tear my hair out with this last and most annoying pothole in the measurement process. I've fought through a lot of software, knowledge, and hardware problems in the past months. Obviously I can't use a DSP type noise remover and expect to use an MLS-based measurement system in the line, or a notch for that matter.

I also checked phantom power to ensure it was clean (47.2V) and AC free.

Do I have a bad mic, or is someone's AC motor in my neighborhood radiating like Cygnus X-1, and is there any way around this problem?


R/Robert

[nick29498141]

My Behringer ECM-8000 has decided to pick up 60Hz and assorted harmonics (120, 180, 240Hz, etc.) from out of the air. To ensure I didn't have a piece of malfunctioning AC equipment in the house I put the laptop on battery and turned off all of my breakers, including the main.

This noise is present on both my MXL mic-mate (XLR-USB 44.1Khz converter) and through my Edirol UA1-EX and mixing board.

I have checked the XLR cable (mic-mate doesn't need one), the mixing board, the USB cable, and even made sure the mic's XLR ground pin was grounded to the mic case (good).

The mic does pick up sound and just to test, I ran pink noise out of the stereo and ended up with a pretty standard in-room pink noise with 60Hz and harmonic spikes protruding. I have a not-so-pretty TrueRTA sweep of it, but it isn't really required for this problem.

I am just about ready to tear my hair out with this last and most annoying pothole in the measurement process. I've fought through a lot of software, knowledge, and hardware problems in the past months. Obviously I can't use a DSP type noise remover and expect to use an MLS-based measurement system in the line, or a notch for that matter.

I also checked phantom power to ensure it was clean (47.2V) and AC free.

Do I have a bad mic, or is someone's AC motor in my neighborhood radiating like Cygnus X-1, and is there any way around this problem?


R/Robert

My first inkling is the mic... it may be bad... is it under warranty? If you got it from PE, call them, they may be able to work something out for you...

[robert]

Me Too. I actually have 2 mic's but one is still with brother in Tulsa. I did buy it from PE and once I get my other one back to compare it with, I'll return the defective one.

R/Robert

[Hal H]

Robert,

Sometimes connections on the electrical service lines outside the house can go bad. A good way to find the offending source is to take an AM radio, not tuned to a station, outside and just walk around. The 60 Hz noise will get louder as you get closer to the source. Once you determine the source, and it is outside the house, the electric company has the obligation to fix it. I'm a ham radio operator and have heard of other hams with 60 HZ interfering with their radios. They get prompt service. (It's illegal to interfere with legal communications)


Hal H

[philiparcario]

Tune your radio to 600 or 660 it will pick up interference it it is out there. summer heat means lots of ac running and outdoor transformers will radiate lots of interference. you can use your car radio and drive by your area. My electric company knows me by first name I have had 4 transformers replaced on my block in the 16 years I live in NJ.

[robert]

Hal / Phil:

If I had points to give, you guys got 'em. The hum at 660 on the AM dial (can't use 600 as there is something there) does appear, and it is loud in my garage.
I have underground lines in my neighborhood, but guess where the power comes in...the garage! LG+E Electrical Mafioso get a call tomorrow, lol. And my Soundeasy/TrueRTA measurement software busted em. I must be getting a thorough dose of low frequency RF right now!

R/Robert

[Hal H]

Good Deal!!! Glad you found it!
Hal