When a 1/4" Mono (2-conductor) plug is used, the adapter's 3pin XLR is wired as follows:
Tip: Pin-2
Ring/Sleeve: Pin-1 & Pin-3
When a 1/4" Balanced (3-conductor) plug is used, the adapter's 3pin XLR is wired as follows:
Tip: Pin-2
Ring: Pin-3
Sleeve: Pin-1