I think GP was referring to the conductors on a standard stereo+mic 3.5mm plug, which of course really has four conductors, but three prominent dividing marks.

I think GP was referring to the conductors on a standard stereo+mic 3.5mm plug, which of course really has four conductors, but three prominent dividing marks. These are unbalanced mics. I've never seen balanced mics outside of recording studios.