Ah, it’s the old pin 2, pin 3 debate. An inSync reader asks: “Some equipment’s audio XLR audio connections are pin 2 positive, some are pin 3. For example, I have a BSS 402 that is pin 3, but all the rest of my studio is pin 2. What pitfalls do I need to avoid when interfacing such gear and how do I avoid them?”
Fortunately these days “most” manufacturers have agreed to make pin 2 hot on their equipment. This means that some manufacturers have equipment that may be either way, depending upon how old it is. At any rate the main thing to understand here is that as long as the connections are all balanced all the reversal does is reverse the polarity of the signal. It doesn’t harm its electrical value. For example if all of your equipment was pin 2 hot, and you hooked up one piece in line that was pin 3 hot you wouldn’t even notice. The signal would be polarity reversed (relative to your studio) going in, and would be reversed again when leaving said piece. The net result is that everything would be in phase and no problems. Problems can arise, however, when going back and forth between unbalanced and balanced systems. Many recent issues of inSync have talked about balanced and unbalanced interconnects (4/26 & 4/8 are two examples). In these cases it is important to be very strict about whether pin 2 or pin 3 is positive.
The best thing to do is to find out if any gear in your studio is wired pin 3 hot (or positive) and make special cables to go between that piece and whatever it is connected to (presumably you just need to get it to a patch bay, but…). That way you can wire it up once and then forget about it. I also label any pin 3 positive pieces with a special sticker I have made up. I just stick it on the back so I always know. Similarly, whenever I make pin 3 hot cables I clearly mark them.