Until Friday our sound board has worked without a problem. Since then we have started getting a loud hum every time i bring up one of the hanging mics. Even if all the other mics are down, we still get the humming. All the other hanging mics are fine, and nothing has been moved or changed. If i cut out the low frequencies, the hum goes away, but doing that messes up everything that mic picks up. Any one have any suggestions on what i could try to get rid of the hum?