Aquired a sterlin condensor mic st51 with a phantom power supply. I never used a mic before so I don't know if im doing something wrong or wrong cables. I get a loud ringing noise that will be present all the time when I bring the volume to 5 on my acoustic amp ( im using a fender acoustasonic 30 amp). The cables came with the mic, but when I look online manual it says to always use high quality XLR cables and the only markings I can find the cables that I have are EXM3. If I don't plug the mic into the amp and just the acoustic I get no noise. Only when the mic is plugged in. I also get the noise when I touch the mic with my hand, it starts the loud ringing. Im sure this isn't normal, I have the power supply ontop of my amp, ill try to move it next time to see if it makes a difference..any input will be greatly appreciated..