Weird noise/feedback based on microphone angle?

Photonic

New member
So, 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. For example, if the mic is at 6 oclock or 12 oclock, it is fine. Otherwise, it gets worse with this noise.

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

Here is what I have tried:
- New XLR cable
- 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 the sound at this point.


The only things I have not checked are a new microphone, which I plan to check soon. Or a new interface. However, either of those just logically do not make sense to me for this problem. If anything, maybe the microphone.

Has anyone had anything even close to this before. I am at my wits end on this. I have spent countless hours troubleshooting.
 
Thanks mjbphotos. I have now tested 3 different xlr mics. They all have the same problem at the same orientations.

Anyone think it is possible it could be rf or something similar?

Seriously driving me crazy
 
My first inclination is to think that this isn't possible with 3 different mics....one maybe.......but not 3.....especially if they are of different makes or models.

So.......let's assume the problem does exist......and all the conditions above were tested.....and there is no outside factor.

OP......in angling the mic......at what point as you move the angle does the problem occur? 1 o'clock........2 o'clock...etc.?

Post a sample when you can.

1000 sincere pardons if I'm wrong but it sure feels like we're getting trolled here.
 
PS: The forum won't let me post the actual links as links, as my account is too new. Sorry. I attempted to overcome this, if this breaks the rules, please let me know and I will remove them.... It just means you will have to do some work to visit the links, change DOT to . Sorry, I have no control there...

I swear to you, I am not trolling. I am so happy more of you responded.

And yes, I tested it with a Shure SM58, Shure SM57 and a Rode Procaster.

Here is how it works for all of the microphones.

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.

imgur DOT 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: vocaroo DOT com/i/s1grprBP7CUQ
Isolated and Boosted: vocaroo DOT com/i/s1P9WmKjpDPX

If you would prefer a different file hosting service, let me know.
 
So FYI. 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.
 
That's quite an amount of field. Not sure to what your meter is calibrated, but here in the UK, EMF from electrical supplies is legislated for - our limits are these.
Exposure
National Guidelines
The Government sets guidelines for exposure to EMFs in the UK on advice from the Health Protection Agency (HPA). In March 2004 the UK decided to adopt the 1998 guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and this policy was reaffirmed by a Written Ministerial Statement in October 2009. These guidelines also form the basis of a European Union Recommendation on public exposure and a Directive on occupational exposure.
The ICNIRP ‘reference levels’ for the public are:
100 microteslas for magnetic fields
5000 volts per metre for electric fields
These are the levels above which more investigation is needed if this level of exposure is likely to occur; the permitted levels of exposure are somewhat higher, 360 microteslas and 9000 volts per metre. They apply where the time of exposure is significant. These guidelines are designed to ensure that EMFs do not interfere with nerves, but were set after examining all the evidence, including the evidence on cancer. The occupational limits are five times higher.

Might be worth checking this out, as your recording setup revealed it to make sure it's actually healthy to be in your studio.
 
That's quite an amount of field. Not sure to what your meter is calibrated, but here in the UK, EMF from electrical supplies is legislated for - our limits are these.
Exposure
National Guidelines
The Government sets guidelines for exposure to EMFs in the UK on advice from the Health Protection Agency (HPA). In March 2004 the UK decided to adopt the 1998 guidelines published by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and this policy was reaffirmed by a Written Ministerial Statement in October 2009. These guidelines also form the basis of a European Union Recommendation on public exposure and a Directive on occupational exposure.
The ICNIRP ‘reference levels’ for the public are:
100 microteslas for magnetic fields
5000 volts per metre for electric fields
These are the levels above which more investigation is needed if this level of exposure is likely to occur; the permitted levels of exposure are somewhat higher, 360 microteslas and 9000 volts per metre. They apply where the time of exposure is significant. These guidelines are designed to ensure that EMFs do not interfere with nerves, but were set after examining all the evidence, including the evidence on cancer. The occupational limits are five times higher.

Might be worth checking this out, as your recording setup revealed it to make sure it's actually healthy to be in your studio.

Thanks. In most of USA, Anything below 5mg (miliguass/that would be 0.5 microtesla) is considered "residential safe" here. In fact, the NIH and many agencies list the "safe" level at less than 100mg. And for workers, it is less than 500mg.

The meter is calibrated, it is a TriField TF2. I drove around for quite some time to test everything. Basically, if you live close to powerlines ANYWHERE in my city (around Dallas), you are likely to have between 1-2mg. If you live next to a transfer station, it can be as high as 8mg. Our large power lines, that carry power into the city generate a field of around 40 when you are close to them. The shielding used, overall, is horrendous.

That being said, if I lived about 1 mile east or south of where I am, I would be in the 0.1-0.3mg fields. That would be about what it is like at work, and it would be 0.01-0.03microtesla. The issue is, there is a main power line literally ~30 feet from my house and a HUGE transfer station around 200 feet from my house. Not much I can do, besides move (Which I am literally considering because of a multitude of reason).

FYI, all of this is Magnetic, not Electric. So I am well within "safety" limits. It is just much higher than you would normally see. I just got unlucky that they build this power transfer station next to my house like 8 months ago.


PS: I am learning all of this stuff. So, some of this could be wrong, but this is what my ~15 hours of research has come up with.
 
I feel for you. However I've also learned something useful. I have an sm7, and rarely use it because I have other mics that do similar and sound similar but now I know that it's a good choice for nasty environments which I didn't know. Cheers
 
Back
Top