eletro-magnetic field induced hum

  • Thread starter Thread starter antichef
  • Start date Start date
antichef

antichef

pornk rock
OK, so I'm in the process of experimenting with mic choice and placement on my new drum kit to try and reduce the number of idiotic questions I ask here, and I ran across a very pronounced issue I hadn't dealt with before. I'm placing a kick mic outside the drum and another dynamic inside, close to the batter. I started with a SM57, and noticed that the inside kick track had a lot of crappy hum - I troubleshot with other 57s and cables, and realized that the inside of the kick appears to be an EM hotspot - the mics are quiet when I pull them out (but there are other spots in the room where they hum also). I went through a bunch of dynamics, and the two that didn't seem to hum much were the Sennheiser MD441 and MD421, so now I have 421 inside the kick, but I'd rather be using it on a tom.

Does anyone have any pointers on how to shield a mic from EM in a situation like this?
 
If you have florescent lighting any where near where you are recording turn them off!!!!!!!!!!!!!
 
wow.. ya got me stumped on this one... i would have suspected a cable sheild/ground being bad... but im resonably sure you would have checked that... build a faraday cage inside the drum??? some wire mesh fashioned into a box that's run to earth...
 
hmm - I could try some cage things - maybe a wire to metal parts of the drum and to the ground. There are no fluorescent lights nearby, but the wiring in the house is so old (knob & tube) that I've got to believe there are all sorts of weird things going on - I'm probably lucky there hasn't been a fire. The outlets are *not* grounded - the previous owner installed three-hole outlets, but the ground connection doesn't go anywhere.
 
do you own the house??? maybe you could rewire just the studio areas??? or run a good ground for it atleast??? maybe do a star grouind for the whole system???
 
As Moresound suggests, *get a ground*. In the meantime try moving the kit so that the kick is in one of those places where the mic doesn't hum. If it hums there, you probably have a metal shell acting as an antenna. Maybe you can tune in WBZ.-Richie
 
Thanks -- I have a room in another part of the house reserved for my studio - I'll make sure to get it rewired properly with romex as part of the project. In the meantime, I'll try moving my equipment around - (hmm.. the bathtub seems like it would provide some shielding -- just kidding :D)
 
You could try running from a battery plus inverter and see if that quiets the beast. Maybe just a UPS to start with to see IF it makes a difference. It could still be flourescent lighting and other sources. Do you live next to a radio tower? Power substation? Cell tower? Office bulding?
 
You must log in or register to reply here.
Back
Top