The instrument cables applied in an audio system - and how they are connected - can play a great hole on the sound of the system. Every instrument cable added to an audio system can both add noise and interfere with the sound quality of the components it connects. Hence, it is essential to use the proper cable for the right task. For that, you need to understand the kinds of signals the cables are carrying.
There are two main factors to keep in mind: the level of the signal and the type of the signal. We’ll save signal level for a future post and will focus for now whether the signals are balanced or unbalanced.
Unbalanced Instrument cables and Signals
Unbalanced instrument cables available for sale out there come with two connectors which, have two conductors each connected by two wires inside the cable. You can often identify an unbalanced instrument cable by its connectors. That is because each wire has to finish at the connector with its own contact point. A standard tip-sleeve (TP) guitar cable is one of the most common unbalanced cable found on stage. Another example of unbalanced cables is standard RCA cables used for many AV components.
This type of cable uses just two conductors and is susceptible to picking up noise. While it works great for connecting a guitar to an amp, but because it is not efficient at suppressing noise from outside interference, an unbalanced cable should have a maximum length of 4 to 6 meters - especially when used in noisy environments.
Balanced Cables and Signals
A balanced cable features three wires in the cable (two signal wires and a separate ground wire ) and three conductors in the connector. As with the unbalanced cable, the ground wire surrounds the signal wires and is applied as a shield against interference. What makes a balanced instrument cable different is the way the gear uses that extra signal wire.
The two signal wires both carry a copy of the signal. However, the two copies are sent 180 degrees out of phase. When two perfectly out-of-phase signals are obtained, they are canceled, leaving you with no sound.
Balanced instrument cables can support longer cable runs, around 15 to 30 meters, but shorter runs often use balanced wiring to protect against noise. Balanced instrument cables are commonly used in the wiring for microphones, signal processor, amps and the interconnect cables between consoles.
Choosing the right cable for the right signal
It is important that you understand that using a balanced cable on an unbalanced signal will provide you no benefits. The jacks on the gear on both ends of the cable need to be designed for balanced signals as well because if not, there will be no circuitry to the phase inversion that creates the noise cancellation. On the other hand, using an unbalanced instrument cable with an equipment that expects balanced signals will work, however the signal will be unbalanced and vulnerable to the same noise as any unbalanced signals.
To find out what type of signal a given jack is supposed to support, check the documentation of your gear.
For more, visit: What Is The Difference Between Speaker Cable and Instrument Cable