SM7B Making Buzzing Noise

[Chrisdb]

So I've had this SM7B a few weeks now, and have just started using it. I picked it up second hand off of ebay. And for some reason it keeps making this kind of buzzing hissing sound. It will be completely silent until the gain is turned up to about three quarters on my 002 Rack and after this point the noise just gets louder by quite a larger amount the more the gain is turned up.

Does anybody know what could be causing this? I can't figure it out The weirdest thing is it's completely quiet until a certain amount of gain has been added.

Thanks in advance for any help

 

[moresound]

You might be using to much gain or the mic is defected.

 

[Big Kenny]

try it through a PA, then you can rule out some variables

 

[soundchaser59]

What if you run a different mic into your 002 Rack and turn the gain up.....does it do the same thing? If you run the SM7b into a different board and turn the gain up, does it still do the same thing? If yes and no, then it aint the mic.