(If this is not the correct spot for this post, I apologize. Is there a more appropriate spot for this post?) I am having an issue when I use an external microphone with my Sony PD-170 Camcorder. When it is connected, it has no buzz, and sounds fine. But accompanying the audio I hear through my headphones (or on the tape, afterward), there is a ringing or buzzing sound that rises and falls with the audio. I have switched the XLR cables that connect the microphone to the camera. I have fiddled with the connection, and it seems stable. I have tried turning the camera audio up and down. I have made sure that the microphone is in its proper stand, so that it picks up no extra vibration. Does anyone have any thoughts on what could cause this?