Networking & Protocols
XLR is a type of electrical connector commonly used in professional audio for balanced analogue and digital signals. Recognised by its circular shape and three-pin configuration, it provides secure, noise-resistant connections for microphones, line-level equipment, and speakers.
The XLR connector was developed by James H. Cannon of Cannon Electric in the 1950s and has since become the industry standard for professional audio cabling. The most common version, the three-pin XLR, carries a balanced signal using two conductors and a separate shield. In this configuration, pin 1 is ground, pin 2 is hot (positive polarity), and pin 3 is cold (negative polarity). Balanced wiring allows external interference picked up along the cable to be cancelled at the receiving end, resulting in a clean, low-noise signal even over long runs.
XLR connectors are widely used for microphones, mixing consoles, preamplifiers, outboard processors, and powered speakers. Their locking latch ensures a secure connection that cannot be accidentally pulled out during use, which is critical in live sound and studio environments. In digital audio, XLR is also used for AES/EBU (AES3) connections, which carry two channels of digital data using the same physical connector type but with 110-ohm impedance cable.
Variants exist with two, four, five, six, or seven pins, used for specialised purposes such as stereo microphones, lighting control (DMX512), or intercom systems. Despite these variations, the three-pin XLR remains the universal connector for professional audio due to its durability, shielding, and reliability.
Understanding correct pin configuration and grounding practices is important to avoid phase inversion or hum. Properly implemented, XLR connections ensure high-quality, interference-free signal transfer across both analogue and digital audio systems.
