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High pitched humming sound from microphone

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High pitched humming sound from microphone

Postby ronweasel » Mon May 21, 2018 2:43 pm

So I bought the EV re320 microphone today. When I got home and tried it out, there was a high pitched humming noise that starts being heard at around 75% volume (on the gain knob) and with the audio interface volume set at 75% as well. The humming noise can be heard from the direct monitor, and voice recordings.

I tried hooking up another microphone (a condenser mic) to the audio interface, and it did not make the same high pitched humming sound. I also tried hooking the re320 with a different XLR cable, though it didn't solve the problem.

To give a little info regarding the setup, the mic is hooked up to the scarlet 2i2 2nd gen audio interface. The audio interface is plugged in my pc, which is right beside the audio interface.

I've also tried plugging in the audio interface to my laptop, in a completely different room. This did not make the high pitch humming noise go away either.

Thanks in advance for the replies!
I'm sorry if the way I explained the problem isn't clear enough! I don't know what some of the things are called, hehe.. :headbang:
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Re: High pitched humming sound from microphone

Postby James Perrett » Mon May 21, 2018 9:02 pm

Is there any chance you could post an audio sample?

My first thought would be to look at the grounding - is the computer properly grounded and is that ground connected through the audio interface to the mic? Do you have anything else that you could plug the mic into? Being a dynamic mic it could also be susceptible to interference - does the sound change when you move the mic?
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Re: High pitched humming sound from microphone

Postby ronweasel » Tue May 22, 2018 3:28 am

Hi James,

I'm not sure whether my computer is properly grounded or not :oops: ... Maybe you can tell me how to find out? I also tried connecting a condenser microphone to the same audio interface with the same XLR cable, and the high pitched sound wasn't there (even at full volume). I don't have another dynamic microphone to try out though. As for moving the mic, that did seem to change the pitch of the noise, but it is definitely still there.

I'll post an audio sample when I get home.

Thanks for the help, btw!
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Re: High pitched humming sound from microphone

Postby Wonks » Tue May 22, 2018 7:14 am

The mic's got a built-in humbucking coil, so it shouldn't be noisy. Hum pickup level for a quoted 60 Hz/1 millioersted field is described as -130dBm. https://www.electrovoice.com/binary/RE3 ... ev%203.pdf

However, the mic cold be faulty, or it might be a grounding issue as James suggests. If you've got a multimeter, check the resistance of pin 1 of the mic end of the XLR cable back to the earth pin of the mains plug (with the PC unplugged from the mains). It should be a couple of ohms at most, but should read less than this. Then plug the mic in and do the same for the casing of the mic to the ground pin. Again, the resistance reading should be almost nothing.
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Re: High pitched humming sound from microphone

Postby ronweasel » Tue May 22, 2018 8:40 am

Hi James,
Here is a sample of the high-pitched sound.

https://instaud.io/2dc0
https://instaud.io/2dc1

The first audio is with the volume of the mic all the way up. The second audio is the mic at around 75% volume, the volume I intend to record at. You can hear the high pitched sound in both audio clips.
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Re: High pitched humming sound from microphone

Postby Hugh Robjohns » Tue May 22, 2018 9:06 am

Here are a couple of views of the quieter file from iZotope RX6.

AAA Spectrum.png


You have an obvious tone at 9kHz, and two more at 18kHz +/-150Hz. There's also a strong component at 150Hz (although it's buried in the ambient noise). They are obviously all related to each other, but the 150Hz component is almost certainly from the interface's mains power supply (assuming you're in the UK/EU), and I would suspect the others to be from an internal DC-DC converter or possibly from the clocking circuitry.

Poor or absent grounding of the interface is a distinct possibility for the cause, and it's what I'd check first... but can I also ask, is the noise the same when phantom power is turned on and off? I'd also see what happens if you turn off (at the mains socket) any nearby screens, and any other wall-wart or line-lump power supplies, as they can generate nasty things like this....

AAA-Noise Spectrum.png


The 9kHz tone is around -105dBFS in the quieter file, and -95dBFS in the louder one -- so they are likely to be drowned out when recording something, and can be easily filtered out if necessary... but they really shouldn't be there.

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Re: High pitched humming sound from microphone

Postby ronweasel » Tue May 22, 2018 10:04 am

@Wonks: I don't have a multimeter , so I can't test that out :( But thanks for recommending that I do that! May be helpful for me in the future!

@Hugh Robjohns: Yes, the noise remains the same with phantom power both turned on and off. As for turning off all the screens in the room, I just tried turning off and unplugging every electronic appliance and machine inside and near the room (monitors, router, computer, chargers) and the high-pitched noise is still there. The only difference this makes is the static-ish sounds disappear. Just wondering, if I have issues with grounding, what can I do to properly ground my computer? I can't seem to find any posts on the internet regarding this.

To add to my observations on the noise, it seems that after further testing the noise sometimes goes away shortly, without changing anything to the microphone (where it is positioned, what it is hooked up to, etc)
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Re: High pitched humming sound from microphone

Postby Brian M Rose » Tue May 22, 2018 12:03 pm

Just another possibility. I had a similar problem and it was a cheap and less than cheerful switch mode power supply plug. These are built to price, not quality I suspect. All of us seem to end up with loads of these around the studio and I do start to wonder....
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