Help me rid myself of this annoying hum
November 22, 2010 9:10 PM Subscribe
Why am I picking up a hum when recording?
posted by bodgy to Technology (16 answers total) 2 users marked this as a favorite
I have been recording in a 2 mic setup for quite some time but lately I have picked up some sort of electric hum. I have spent 2 hours trying different configurations and now, frustrated, I am turning to you Mefites for assistance!
I have two Shure SM-57 microphones. They are connected by XLR to a Behringer X1204USB 12-Channel Mixer, one on Input 1, the other on Input 2. The mixer is then connected to my Macbook pro through an RCA to 1/4" adapter cable.
The hum is something new the past few months.
My troubleshooting steps:
*Plugged Headphones directly into the Phones jack of the mixer, yep I hear the hum.
*I checked all the mixer board settings. I set everything to 0 and the hum went away (though I did hear a bit of ambient static). As I brought up the sound to either microphone the hum came back. I tested some recording levels, and my recordings were overly soft. By the time I got up to where I was hitting 0.5 on the Mac (with the Mac's recording input maxed out) the board's settings were all pretty high and the hum was very audible.
*I tested this with one mic then the other. Both mics demonstrated the hum.
*I then replaced the XLR cable between one mic and the board. Hum still there.
At this point I'd tried 2 mics, 3 XLR cables, and 2 outputs all with identical results and thought perhaps my board was bad. So I pulled out my old Nady MXE-612, hooked up the two mics, plugged my phones in the jack...and there's that god damn hum!
Now I am listening to my room. I do NOT hear this hum. I have turned off everything in the room including the lights. I have UNPLUGGED everything in the room except the mixing board. STILL THIS HUM...
The hum is NOT constant but it is rhythimic. In the recording software I see it ebb and flow like a sine wave. I don't know what to make of it.
I have uploaded an MP3 of this sound to http://cilff.com/wtf.mp3 The beginning is the hum when the levels are set at a recording volume where my words can be picked up. The end of the WAV is where I turn everything WAY up to get the maximum noise and show the way it comes in and out ever so slightly.
At this point I am willing to buy whatever needs to be bought to get rid of this hum, but I'm not even sure if it's a "replace the part" problem as I have replaced every single component now and still get the hum.
I'm losing my mind...please help!