An XLR cable is a type of audio cable commonly used to connect professional and high-end hi-fi equipment. In a hi-fi system, XLR cables are often used between components such as DACs, preamplifiers and power amplifiers.

The most common audio XLR connector has three pins. One provides the ground or shield connection, while the other two carry versions of the audio signal with opposite polarity. This arrangement allows XLR cables to be used for balanced audio connections.

A balanced connection is designed to reduce unwanted noise and interference. The receiving component compares the signals carried by the two signal conductors. Noise picked up equally along the cable can then be rejected while the wanted audio signal is retained. This process is known as common-mode rejection.

This ability to reject interference makes balanced XLR connections particularly useful over longer cable runs. It is one reason XLR cables are extensively used in recording studios, live sound systems and other professional audio environments where cables may run alongside equipment capable of producing electrical interference.

In a stereo hi-fi system, separate XLR cables are normally required for the left and right channels. For example, a preamplifier may have left and right balanced XLR outputs that connect to corresponding inputs on a stereo power amplifier.

XLR connectors also have practical advantages. They are relatively robust and commonly incorporate a locking mechanism that helps prevent the connector from being accidentally pulled out of its socket.

XLR and RCA connections can both be used to carry analogue audio, but they operate differently. A conventional RCA connection is unbalanced and uses one signal conductor together with a ground connection, whereas a balanced XLR connection uses two signal conductors together with a shield or ground.

An XLR connection does not automatically provide better sound quality than an RCA connection. The design of the equipment at either end of the cable is important, and some hi-fi components may provide XLR sockets without using a fully balanced internal circuit.

For equipment designed to operate with balanced connections, XLR cables provide a robust and effective method of transferring analogue audio signals while offering excellent resistance to noise and interference.