XLR pin numbering and connections?

[Jim R.]

Ok, I cannot find a verbal description of this anywhere, only pictures that I can't use.  I know others have had this same question, so perhaps a sticky is in order?

Anyway, can somebody describe the pin numbering and conventional headphone connections for both a 3 and 4 pin XLR connector?  To keep things simple, assume I'm looking at the  wiring side of a female chassis mount connector and the 4 pins are at the bottom of the circle.  So, what pins, are what and in what order, and which pin goes to what connection on a headphone?  And for 3 pin connectors, what are the pin assignments for both single-ended and balanced configs and what is typically done with shields?

Any of you headphone guys who have experience with this, my thanks in advance for helping me sort all this out once and for all.

-- Jim

[Doc B.]

I don't know the convention for four pin, but the three pin XLRs are wired to the standard balanced connections - pin 1 shield, pin 2 signal hot, pin 3 signal cold. On a three pin XLR the three pins are situated at roughly 2 o'clock, 6 o'clock and 10 o'clock. These should be a ridge on the rim of the plug nearest to pin 2 on a female connector, and there will be a matching groove in the male connector near pin 2. If you say pin 2 is at 10 o'clock then pin 1 is at 2 o'clock (or vice versa) and pin 3 is at 6 o'clock. For unbalanced connection pin 1 and pin 3 are connected at the output jack.

On an XLR jack there is an extra lug on the back. This is connected to the shell on a metal jack. This is the point where you tie pin 1 to the chassis.

[Jim R.]

Thanks, Dan -- that helps a lot.

Anybody have the 4-pin info?

Thanks,

Jim