What could cause a USB mic to all of a sudden start picking up a hum?
May 10, 2011 3:34 PM   Subscribe

My USB Mic started picking up an omnipresent hum all of a sudden. It never used to. Any ideas what could have changed?

Here's a link to a picture of the frequency. This is with no speaking, jsut the mic running. This did not occur previously. Nothing notable has changed with my computer, and I have tried the following:

-changing USB ports
-Unplugging other devices, usb and otherwise
-changing the USB cable.

Still the hum remains. Any idea what could have changed to cause this, or other variables I might try removing from the equation?

The mic is a Samson CO1U, and I was very happy with it until this seemingly random switch was flipped.
posted by JoeGoblin to Technology (10 answers total)
Response by poster: FWIW, I'm running Windows 7. Have been recording in Adobe Audition 3.0 and Audacity.
posted by JoeGoblin at 3:35 PM on May 10, 2011

That's 60 Hz power line noise-- the frequency of alternating current. Caused by something being grounded poorly, or not at all.

Is it a laptop? Did you go from wall power to battery, or vice versa?
posted by supercres at 3:40 PM on May 10, 2011

Response by poster: No, it has been a desktop computer the entire time. Any tips for what might cause it on a desktop?
posted by JoeGoblin at 3:49 PM on May 10, 2011

Have you changed power outlets that you're computer or any of it's peripherals are plugged in to? If so, is there anyway that they might be on different breakers or circuits now?
posted by AaRdVarK at 3:51 PM on May 10, 2011

Plugged anything new into the same circuit? New fluorescent desk lamp?
posted by pupdog at 3:53 PM on May 10, 2011

Other things that have done this to me in the past include TV/cable wires, air conditioners, and oscillating fans...
posted by vorfeed at 4:01 PM on May 10, 2011

Have you dropped or jostled the mic recently? Could something be loose inside of it or on it that's generating the super low hum?
posted by patronuscharms at 4:13 PM on May 10, 2011

Gradually isolate the problem: plug the mic into another computer and try to replicate the hum.
posted by Blazecock Pileon at 4:20 PM on May 10, 2011

You might want to just try moving cables around - I've found that having a cable near a mike/speaker cable can be enough to cause a bit of a hum, and shifting things just a little bit tends to help.
posted by robintw at 5:16 PM on May 10, 2011

Yes, switch cables, move your display/speakers/table lamp/cell phone around, and remove everything that's plugged to the same circuit, one by one. By switching set up entirely (bring the microphone towork, or home), you could quickly rule out the microphone itself.
posted by ddaavviidd at 6:25 PM on May 10, 2011

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