Balanced audio is a very clever way of transferring an audio signal without picking up external electrical noise, or hum. Electrical hum is caused by stray magnetic fields, causing a vibration in the air. Think of the hum of a flourescent light. This is why, especially in professional recording studios, balanced cables are vital.

An unbalanced cable contains only 2 wires; the “conductor” to send the signal to the amplification device and the ground (earth) wire to remove any low frequency and Radio Frequency (RF) interference.

Commonly found unbalanced cables are your standard RCA cables, or TS (Tip, Sleeve) guitar leads.
RCA connector Guitar Patch Lead (TS)
Due to the lack of protection against interference, unbalanced cables are best used in shorter lengths, no more than 15-20m. Imagine being at a concert to see your favourite band. With the stage and the mixing desk 100m apart, you would be unlikely to hear anything over the electrical interference.

A balanced cable, such as an XLR or TRS (Tip, Ring, Sleeve) cable, consists of 3 wires; 2 conductor wires and one earth wire.

XLR                                           TRS

The earth wire will remove the low frequency and RF interference in the same way as in an unbalanced cable. However, the 2 conductor wires make it really interesting.

Let us use vocals through a microphone as an example.

The vocal signal will be sent through the 2 conductor wires, which send the 2 identical signals 180 degrees out of phase, or as positive and negative.

Normally, signals being sent out of phase would cancel each other out.

However, a balanced cable comes into its own when inverting the second signal. Rather than cancelling out the signal, it actually becomes stronger.

Imagine the electrical interference is shown in red here:

As both positive and negative conductors are picking up the same electrical hum, when the second, or negative, signal is inverted, the interference becomes the negative.

A balanced cable will cancel out the electrical interference, giving a clean, crisp sound over distance.

If you would like to ask more about balanced audio cables, feel free to call one of our Selby Techs on 1800 69 2225