AES 14-1992 (r2004) defines the pinout of 3- and 5-pin XLR connectors.
AES14-1992 (r2004) AES Paper pdf
'This standard shall apply to three- and five-pin circular connectors, commonly and generically known as XLRtype, used for the interconnection of all categories of sound system components for professional audio, commercial, recording, broadcast, and similar applications, regardless of function, type, or level of the signal. It specifies the application and polarity of analog signals for these connectors. This standard does not pertain to the dimensions of the connectors.'
|Application and supply||1||2||3||4||5|
|Single-channel, balanced||Screen (shield)||Positive polarity||Return|
|Single-channel, unbalanced||Screen and return||Positive polarity||Note 1|
|Single-channel, balanced, phantom supplied||Screen and negative supply||Positive polarity; positive supply||Return; positive supply|
|Single-channel, balanced, A-B supplied||Screen||Positive polarity; positive supply||Return; negative supply|
|Two-channel, balanced||Screen||Left-channel positive polarity||Left-channel return||Right-channel positive polarity||Right-channel return|
|Two-channel, unbalanced||Screen and return||Left-channel positive polarity||Note 1||Right-channel positive polarity||Note 1|
|Two-channel, balanced, phantom supplied||Screen and negative supply||Left-channel positive polarity; positive supply||Left-channel return; positive supply||Right-channel positive polarity; positive supply||Right-channel return; positive supply|
|Two-channel balanced, A-B supplied||Screen||Left-channel positive polarity; positive supply||Left-channel return; negative supply||Right-channel positive polarity; positive supply||Right-channel return; negative supply|
|Note 1. If an unbalanced amplifier input is to accept a balanced microphone, contact 3 (or 3 and 5) of the input shall be connected to contact 1.|