Balanced vs. Unbalanced Audio Systems and XLR Jacks Explained
Balanced vs unbalanced audio explained: three-conductor and two-conductor cables, why balanced systems carry less noise, and where XLR jacks fit.
Balanced and Unbalanced Audio Systems Commonly Used with XLR Jacks - An audio system is a chain of audio devices that generally process an audio signal from an input to an output device. That chain always includes cables, and the cables act as antennas that pick up electromagnetic noise. This electromagnetic noise is usually produced by equipment such as computer monitors and other electrical devices. In audio systems you will come across the terms balanced audio system and unbalanced audio system. Here is the full explanation.
Balanced Audio System
A balanced audio system has a distinct physical build: it has three conductors, with two wire conductors wrapped or enclosed in the middle. The third conductor is a braid and foil that works as a shield against electromagnetic interference. The three conductors each have their own job: positive input signal, negative input signal and ground.
Why Does a Balanced Audio System Use Three Conductors?
When noise is induced on the positive input and the negative input, both pick up the same noise. When the noise reaches the next device, one of the signals is flipped (inverted) and then the two are summed. The result is a clean output signal, just like the original input. This inversion turns out to have an advantage.
What is the advantage? All interference or disturbance picked up along the length of the cable cancels itself out, which is known as cancellation / out-phase, by the time it reaches the end of the cable. The conclusion is that a balanced audio system tends to carry much less noise. The jacks or connectors commonly used in balanced audio systems are TRS and XLR jacks.
Unbalanced Audio System
The opposite of a balanced audio system is an unbalanced audio system. It generally uses only two wires: one is the input line and the other is ground. Whether the device is stereo or mono, if its cable uses two wires, it is an unbalanced audio system.
This kind of audio system carries a high risk of noise, because an unbalanced audio system is vulnerable to interference from electrical equipment or transmitter stations. Noise occurs when interference waves from electrical equipment penetrate the cable and are carried into the sound equipment. The risk of interference grows as the cable gets longer, so the longer the cable, the more the noise damages the audio quality.
The noise can come from electromagnetic waves. These waves can be produced by devices such as air conditioners, transformers, fans and so on. The noise they cause is usually a hum at a frequency of 50 Hz to 60 Hz.
That is the difference between a balanced audio system and an unbalanced system as commonly used with XLR jacks. Clear now, isn't it?
