Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. THe XLR connector is an electrical connector design. XLR Plugs and sockets are used mostly in professional audio and video electronics cabling applications, for microphones and line level signals. HOme audio and video electronics normally use RCA connectors for line level signals generated by a preamplifier. PHone plugs are also used for microphones in home and computer applications. IN reference to its original manufacturer, James H. CAnnon, founder of Cannon Electric in Los Angeles, California (now part of ITT Corporation), the connector is colloquially known as a cannon plug or cannon connector. ORiginally the "Cannon X" series, subsequent versions added a Latch ("Cannon XL") and then a Rubber compound surrounding the contacts, which led to the abbreviation XLR.