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Weird noise/feedback based on microphone angle?
Old 4 weeks ago
  #1
Here for the gear
 

Weird noise/feedback based on microphone angle?

Hi all, forgive me if this is the incorrect forum. Not sure where to put this.

When I record, I am getting a high pitched humming sound in the 500-650hz range. However, this only occurs if my microphone is at specific angles. If you hold the microphones directly up|down the noise nearly goes away. If you hold them horizontal and spin them around that axis (so pan left to right, not tilt up and down) it works like this: 12 o'clock and 6 o'clock would be super noisy, but 9 o'clock and 3 o'clock would be super clean. I made an image to help understand. Imagine this as a top down view of the microphone and you pan it around. The closer to white, the less noise, the closer to black, the more noise.

https://imgur.com/6GWqRg2


Here are two clips. One that is a pure recording, with some background noise. You will need good headphones and to turn it up to hear the 500-650hz frequency that is happening. The louder hum is normal background noise from the AC that I can't shut off right now (I did when I tested if anything was causing it before). The second clip is one where I isolated that frequency range and boosted it by around 30db so that you can clearly hear it.

Pure: https://vocaroo.com/i/s1grprBP7CUQ
Isolated and Boosted: https://vocaroo.com/i/s1P9WmKjpDPX

If you would prefer a different file hosting service, let me know.

Here is the setup
- Rode Procaster XLR
- XLR cable into RME Babyface Pro
- Babyface into PC
- PC into PFC UPS into wall.

Here is what I have tried:
- New XLR cable
- Different mic
- Different outlet (but my system is on a pure sine wave filter anyways, and should have no ground loop noises)
- Different USB ports
- Turn off all devices in room to ensure it is not from a source
- Detach mic from stand and move it around room (0 change, only the mics orientation changes it. But 6 oclock in one section of the room is perfect no matter where in the room it is... The angles do not change if I move the mic)
- Decibel measurements around room, nothing.
- Encasing the microphone in sound proofing, still happening... so I really don't think it is picking up external sounds at this point.


The only things I have not checked is a new interface. However, the problem only starts once a mic is plugged in. Even with an XLR cable only, or no cable at all, the signal is clean.

Has anyone had anything even close to this before. I am at my wits end on this. I have spent countless hours troubleshooting. I have also checked a fair amount of other forums/discords, and no one has been able to figure it out.
Old 2 weeks ago
  #2
Here for the gear
 

Sadly... no one really helped me here... but I figured someone might benefit from my knowledge.

I got it fixed... mostly.

Here is what it was. The power lines and transfer station in my area are causing higher than normal levels of EMF. I have a TriField tester and my average Magnetic field is 2-4. To give you an idea of how much higher this is than normal, at work the field is 0.1. The 540 hz frequency I was hearing was from the 9th harmonic of the 60hz produced from these issues.

After talking with some of the engineers at Shure, they recommended the SM7B because it has a humbucking filter that helps reduce these issues. I can tell you right now, it worked. I can still hear it, but I have to try very hard, and with a very VERY small amount of EQ, it is inaudable.

So yeah... I wasn't crazy. I spent a ton of time and money, but I figured it out. So I thought it might be a good idea to post this here, in case anyone else ever has this issue.
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