Constant Buzzing In Microphone Even When Unplugged


Aug 22, 2013
As the title states there is a constant buzzing / humming in my microphone even when the microphone is unplugged. I'm running an Excelvan BM-800 Condenser Microphone to a innogear phantom power box and then straight to my pc via 3.5 usb dongle or just to the microphone input jack.
Some things i've tried are listed below
1.) Moved the power strip to a different outlet to make sure it wasn't a ground issue (however i sometimes get a ground loop buzz but i cant find the source, happens very rarely though.)

2.) Unplugged a harddrive, some fans, and a DVD Drive to reassure myself it wasn't anything caused by mechanical noise from inside the pc itself.

3.) Moved my microphone around the room because one forum said it could be an issue relating to (electromagnetic?) interference.

4.)Unplugged the microphone. When i do that the buzzing is still there and at the same volume.

5.) Used a laptop, same outcome.

6.)Rolled up in a ball and cried. (not really but it's almost come to that)

PC Specs:
AMD Athlon X4 860k (overclocked)
Corsair H60 Liquid CPU Cooler
MSI A68HM-GRENADE Micro ATX Motherboard
AMD Radeon R7 250x 1GB
8 GB DDR3-1600 RAM
XFX TS 550W 80+ Gold PSU
Windows 10

Any help is greatly appreciated! Thanks!

((Sorry if incorrect threat category))

Shaun o

In some cases the buzz can be down to the microphone gain controls in windows sound manager.
If the gain is set to high then the buzzing can be loud and noticeable if over 10% or more gain.

The other causes can be down to the 2.5mm jack and the in put ports of the computer.
And depending on what country you live in how the system case is grounded.

In three pin plugs in the uk you have a ground wired to the cord or plug of a device running from the mains socket.
Due to the higher 240v used.

where as in the US there is no ground wired via a plug or socket to the wall outlet as it is set at a lower voltage of 110v in most cases.

That means you have to create a ground from the case or metal chassis of the pc case to ground.
A simple wire to the dirt floor, earth.

Most of the time to correct it in the advanced windows sound panel just click on recording devices or communication devices and lower the gain to 5% or 10% while the main playback volume is set higher in windows, also disable any line in devices.
And make sure listen to what you record is not ticked in advanced sound options.

If you have a software app that came with the motherboard you may also have to change the settings in that also for mic gain % and playback device volumes.



Aug 22, 2013

My power strip says "grounded" but god knows if that's correct. I stopped using the 3.5mm plug and use a USB sound card that has a 3.5mm jack on it. I did some surgery and took apart my microphone and the two XLR cables. One of the xlr cables had some wires shooting out of it so i tucked those what seemed to be back in place. I'm not quite sure if that fixed the ground problem or not BUT i feel like i have narrowed down the problem to a bad XLR cable. When i unplug the XLR cable that goes to my MIC the buzzing is still present. HOWEVER, when i unplug the XLR that goes to my pc the buzzing STOPS, even when the 3.5mm jack is in the PC. Thank you for your detailed response and let me know if a bad XLR cable could be the problem.

UPDATE:: I finally fixed it! Turns it out it could've been a multitude of things but ill post everything i did that may have been the culprit instead.

1.) Turned off AGC
2.) Bought a new XLR to 3.5mm cable
3.) Changed USB sound cards (this one seemed to have the most effect)
4.) Got rid of any 3.5 male to 3.5 female extension cables

Thanks for your help!
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