XLR: still a wise choice for professional audio and video equipment


The XLR connector is over 60 years old yet is still a popular choice for professional audio and video equipment makers


The XLR connector has been a mainstay of professional audio equipment for many years. Though its origins date back to the 1950s, when it was known as the Cannon plug or jack, it is still very popular for a wide number of audio and video applications. The XLR is extremely robust and is thus still a popular choice for professional equipment.


The connector has gone through many modifications since its invention by James H Cannon, and these modifications started even in the early days with the addition of a locking mechanism and synthetic rubber insulation. Other manufacturers later started making XLR style connectors and there are now standards covering various XLR designs.


Even though XLR is now a generic term, the original XLR was designed by Cannon with the contacts housed in a resilient polychloroprene compound insulator. The XLR term today refers to connectors that followed the path from the Cannon XL connector and not the XLR. The original connector was the Cannon X. The L got added when the latch was invented and the R was for the rubber insulation.



The IEC standard for the XLR has quite a broad tolerance for the distance between the body of the connector and the end of the female contact. As such, different manufacturers have gone to different ends of the specified range and that needs to be checked when ordering connectors, as some times this can result in them not latching properly with the male connectors.

The AES14 standard for XLR connectors was what fixed that equipment outputs would always be on the male versions of the connector and that the inputs would be on female connectors. This ended confusion caused in Japan where the opposite was used for line level connections though not for microphone connections.



Today, XLR connectors come in various styles ranging from three to seven pins, the most popular being the three-pin version that can be found in most professional microphones. A good example is the Neutrik NC3FX (RS stock number 405-590). This is a three-way straight cable mount XLR connector, with silver over nickel plated contacts, a current rating of 16 A (Amperes) and a voltage rating of 50V (Volts).  The connector and cable assembly is straightforward, employing few parts with no assembly screws required. Parts are polarised and securely fitted, thereby eliminating connector noise. Available in either nickel or black chrome finishes, the cable mounting parts have a self adjusting strain relief for cable diameters between 3 and 8mm, and mated connectors are secured by a latch.



Neutrik NC3FX three-way straight cable mount XLR connector


Four-pin XLR connectors have various uses including DC power connectors for professional film and video cameras. They also have applications in stage lighting and pyrotechnic equipment. The Neutrik NC4MX (RS stock number 405-641) is a four-way male straight cable mount XLR connector with silver over nickel plated contacts, a current rating of 10 A (Amperes) and a voltage rating of 50V (Volts). Again, the connector is designed for easy assembly and mounting to the cable is straightforward.



Neutrik NC4MX four-way male straight cable mount XLR connector


The five-pin XLR is commonly found in DMX512 digital lighting controls, stereo microphones and stereo intercom headsets. Amphenol makes the AC5FPZ (RS stock number 666-0664) five-way female panel mount XLR connector. This tin-plated unit uses solder bucket terminals and has a positive latch lock system. It features a leading first-mate last-break contact.



Amphenol AC5FPZ five-way female straight panel mount XLR connector


For dual-channel intercom systems and stage lighting control systems, six-pin XLR connectors can be used. A good example is the Amphenol AC6AFJ (RS stock number 666-0572) six-way female straight cable mount connector, tin-plated contacts, 7.5 A current rating and a voltage rating of 133V AC. This can be quickly and easily assembled without screws and uses the patented Jaws cable retention system that can handle up to 44kg of strain for cables with an outside diameter up to 8mm.



Amphenol AC6AFJ six-way female straight cable mount XLR connector


The seven-way XLR connectors were once used for analogue lighting control systems and wired intercoms in broadcast studios, but are now more commonly found in remote controls for fog machines and connecting valve condenser microphones to power supplies. Switchcraft has a range of XLR connectors in panel mount, cable and inline versions in different contact versions suitable for outdoor communications equipment, general audio applications and instrumentation, and stage lighting. These use solder contacts for ease of assembly and a good example is the AAA7MZH (RS stock number 810-4674) seven-way male cable-mount connector with a voltage rating of 500V RMS.



Switchcraft AAA7MZH seven-way male cable-mount XLR connector




The range of electronic components available from RS Components includes XLR connectors and a wide range other industry approved audio and video connectors for businesses and engineers worldwide, including products from Switchcraft, Neutrik, Amphenol and ITT Cannon.