XLR connectors contain anything from 3-7 pins, dependent on what it being used for.
3-Pin: Balanced audio (most common). 4-Pin: standard connector for intercom headsets, DC power, and two pins is used for the mono headphone signal and two pins for the unbalanced microphone signal. 5-Pin: DMX512 digital lighting control. 6-Pin: dual channel intercom systems. 7-Pin: Fog machines for remote control.
An XLR cable can carry an audio signal easily up to a 1KM, without hardly any interferance. thumb|left|300px|This clip demonstrates how to solder an XLR connector.
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