The XLR Cable is the go-to standard for providing high-quality audio inputs such as microphones. This post will discuss in detail about what is XLR Cable, how it works, its components, pins of XLR connector, best XLR Cables to USB & Mic, applications, advantages, & disadvantages.
What is XLR Cable
XLR Cable is a type of electrical connector, and its full form is “Extended Line Return.” XLR Cables are a vital component in any home and even professional studios.
Fig. 1 – Introduction to XLR Cable
These cables are found mainly in professional video, audio, and stage lighting equipment. In general, XLR connectors are related to audio devices, for instance- speakers, amplifiers, microphones, and soundboards, but they can also be used with low-voltage power supplies, lighting control, and few other purposes.
XLR Cable Connectors are best option as they can effectively and cleanly pass a large electric current across audio devices in a standardized way. An example of this is Phantom Power.
Fig. 2 – Phantom Power
Invention of XLR Cables
James H Canon invented the XLR Connector and is also the founder of Canon Electric which is based in Los Angeles, California, and is now part of ITT Corporation. The name XLR has its origin in a specific X connector from Canon Electric that was modified with a synthetic rubber compound (the R comes from this component) and a latch (this is where the L comes from).
The XLR Cable was originally produced as the Cannon X series, and a latching mechanism was added in the year 1950. After going through many design changes over the years, the final version of this cable was produced in 1955, which had female contacts made of synthetic rubber Polychloroprene. This is the version of an XLR Cable that we all know today.
Design of XLR Cable
The XLR Cable has a circular design having three to seven pins. For audio purposes, there are three pins; one is for the positive polarity, the second one is for negative polarity, and the third one is used as a cable shield (chassis ground).
Fig. 3 – XLR Cable Assembly
Most of the professional microphones (condenser, moving-coil dynamic, ribbon, etc.) have an XLR output, and generally, they have a 3-pin male XLR Connector. A vast majority of inputs for microphones (such as audio interface, adaptor, mixing console, audio snake, etc.) also have an XLR input.
An XLR cable uses a balanced connection. Balance connection is a method of connecting audio devices that enables traveling of signals through lengthy cables effectively without losing clarity of the audio.
XLR Cable Components
Basic 3-pin XLR has the following components:
- Male 3-pin XLR Connector
- Female 3-pin XLR Connector
Male 3-pin XLR Connector
This has three pins that act as plugs, and they are inserted into female 3-pin XLR connectors when connection is required.
Female 3-pin XLR Connector
The three pins in a female XLR Connector act as sockets or jacks and receive the male 3-pin XLR Connector when connection is established.
Let us take the example of a standard microphone connection that has three devices in use. i.e.
● The professional microphone with an XLR output connector.
● 3-pin XLR Cable which is also called a mic cable.
● The microphone input, for example, when a mic is connected to an audio interface.
The connection is made by connecting the male XLR output of the microphone to the cable connector’s female XLR. Then the cable’s male XLR is connected to the mic input’s female XLR of the audio interface.
Pins of XLR Connector
The size of an XLR Connector is almost double the standard RCA (Radio Corporation of America) plugs and sockets that are found on many consumers equipment. The three pins of an XLR Connector are:
- Pin 1
- Pin 2
- Pin 3
Fig. 4 – Pins of XLR Connector
This is the shield or ground wire that provides a reference point for the other pins (pin two and pin three). This pin may also connect to the ground of the mic input or microphone. Apart from acting as ground, this pin also acts as a cable shield and protects the other two pins from electromagnetic interference.
This is the positive or hot wire that carries a copy of the audio signal in positive polarity. For a microphone connection, This pin carries the positive mic signal from the microphone to the mic input.
This is the negative or cold wire that carries a copy of the audio signal in reverse or negative polarity. Pin 3 carries the negative mic signal from the microphone to the mic input for a microphone connection.
How does XLR Cable Work
The audio signal delivered by XLR Cables is balanced, which means the cable filters out any interference that is picked up by an audio signal, thus reducing the overall noise level. When two balanced devices are connected, the XLR Cable carries the audio signal through the positive and negative wires, which have opposite polarities. When the signal reaches the end of the cable, the cable re-inverts the polarities, which phases out or cancels out any external interference which the audio signal might have picked up.
Fig. 5 – Working Principle of XLR Cable
Let us understand the process in detail:
- The XLR Cable microphone generates the audio signal and outputs it on pin 1 and pin 2 with equal amplitude, but one of them is inverted by 180 degrees.
- The positive and negative audio signals are the same, just that they have opposite polarities.
- These identical audio signals travel across the balanced XLR Cable to reach the next audio device. These signals are completely out of phase with each other.
- If there is any electrical interference, the noise enters the positive audio as well as the negative audio signal. The noise signals are not out of phase with each other.
- Any audio interface’s mic input will most likely have an in-built pre-amplifier that expects mic-level balanced signals. This pre-amplifier has a Differential Amplifier.
- The Differential Amplifier at the receiving end of the device inverts back one of the signals so that the positive and negative signals are not cancelling each other out.
- At this point, the original audio signal is now in phase while the noise is out of phase. This results in cancelling out any noise that was picked up on the way, leaving the original signal intact.
- Additionally, due to the recombination of both sides, the original signal gets strengthened. This helps in compensating for any loss of signal strength while running through a long cable.
Applications of XLR Cables
The quality of XLR Cables that renders it most useful is that it is balanced. By virtue of this property, it can be used both for recording studio applications and live sound applications.
● Most microphones are connected by XLR Cables.
● By using XLR Cables, mixing boards can deliver Phantom Power to microphones.
Advantages of XLR Cables
The advantages are:
- XLR Cables provide balanced audio, which protects the cable from external audio interferences from devices like mobile phones, etc. For sending audio signals over long distances, XLR Cable is very effective.
- They provide protection from electrical damage since pin 1 (ground pin) always connects first while the other two pins connect simultaneously.
Disadvantages of XLR Cables
The disadvantages include:
- The usefulness of XLR Cables to deliver balanced signals is possible only when devices on both ends of the cable are also balanced. If there is any misbalance in any device, then it will destabilize the whole signal.
- They are expensive.