Feedback problem

[obiwan177]

This question isn't Venue related at all, but I hope you can still answer it for me. The other day I was doing sound for a live concert, and I was going to use a condensor mic (AT2035) to mic an acoustic guitar. The mixer I was using had only one phantom power button, so all mic channels were powered. I only had one SM58 in the mixer at that point, and as soon as I turned the AT2035 up a bit the monitors started feeding back instantly. I turned the phantom power off and took off the condensor, and then everything was perfect. Was it the phantom power or the sensitivity of the mic that caused all the feedback?

[albee1952]

Phantom should not have caused it(turning off the condenser would have ruled it out one way or the other). Mic'ing an acoustic guitar for live is dicey at best.

[Tiginbna]

The answer to your question: Was it the phantom power or the sensitivity of the mic that caused all the feedback? is "Neither". Phantom power is what makes a condenser mic work. It applies the power (+48 volts dc) like a battery might in an active direct box. When you turned off the phantom power you effectively turned off the AT mic. Unless you have a very controlled environment I would avoid putting a large diaphragm condenser mic on an acoustic instrument. Try an AT 35, ATM350, or a 450, Shure SM-98 etc, but only if the instrument does not have a pickup/direct box output or something like that.

[obiwan177]

Oh ok. I was just making sure that the phantom power didn't somehow adversely affect the dynamic mic. I had just seen some people using condensors live to mic acoustic (john mayer) but I guess it's not too common for that reason.