I was looking around in my basement and found a OLD Electro-Voice 50's style mic. It has that old unbalanced screw-on type conector on the bottom (only one wire). If I wanted to take out that screw on conector and replace it with a male XLR. Witch pin do I connect the wire to.
You'll need a DI or a transformer to balance the signal, unless you just want unbalanced XLR. In that case, just wire pin 2 to the center terminal, and pin 3 and 1 to the outside casing, if this is the connector i am thinking of.
This brings up the more general topic of how to connect older, unbalanced devices to modern balanced systems. While it's always best to use a DI box to provide the best quality audio, if you don't have one available this RaneNote may be of help: http://www.rane.com/note110.html
RaneNote 110 contains practical information on how to connect virtually any two audio devices together properly without interference, humming, and the like.