Three-pin in audio use XLR connector

left right: cannon xlr3-12c (line), switchcraft x3f (line), neutrik nc3mp panel, neutrik nc3fp panel



xlr , 0.25 inch trs phone connector combo jack.

eia standard rs-297-a describes use of three-pin xlr - known xlr3 - balanced audio signal level applications:

prior introduction of standard, wiring of pins 2 , 3 varied. pin 2 hot , pin 3 cold convention typically used european , japanese equipment manufacturers, american companies used pin 3 hot , pin 2 cold . caused problems when interconnecting equipment unbalanced connections. pin 3 hot convention obsolete still found on vintage equipment. pin 1 has been ground and/or shield if cable shielded, , many connectors connect internally connector shell or case.

although covered in industry technical standards, there still disagreement on best way handle use of pin 1 grounding (earthing). main controversy whether shell of connector should connected pin 1 or shield, or left floating. aes standards mentioned above recommend shells of cable-mounted connectors should never connected pin 1 or shield, because inadvertent contact of shell grounded surface while in use can create unwanted current paths fault current, potentially causing hum , other noise. on other hand, equipment containing active circuitry should have pin 1 connected conductive enclosure of equipment close possible point signal enters enclosure. argument centers on radio frequency shielding provided shell of connector, may reduced if left floating. alternative solution connect shell pin 1 , shield through small value capacitor, providing rf shielding allowing little audio-frequency current flow. capability can built fixed jack or cable terminated xlr connectors.

the standard signal flow audio in xlr connectors output male connector , input female. in other words, pins on plug point in direction of signal flow. opposite of power connector standards use female connectors outputs, convention influenced need prevent accidental contact dangerous voltages. however, voltages of microphone , line level audio signals not hazardous. male xlr incorporated in body of microphone.

since equipment requires input on trs phone jack or xlr connector, neutrik , amphenol offer several models of combination connector accept both xlr , 0.25 inch ts or trs phone plugs.