Just after you buy your favorite synthesizer, drum machine, speakers, microphone, MIDI controller, or instrument, you realize that there is no use for them without cables to connect them and transfer signal from one to another.
Cables are the veins of your studio setup for without them your gear would just sit there and decorate your studio. Not only they are necessary for routing your gear but they have a huge impact on the quality and the power of that signal they transmit. Cables come in different types and categories, from analog ones transmitting electrical signal to digital ones transferring binary data.
Analog audio cables transmit analog signal, an electrical signal which alternates its voltage between positive and negative in a sine-wave pattern. These cables carry a system’s lowest-level signal and require careful consideration be given to isolation from their external environment.
The analog cables come in different types and have distinct connectors to connect gear with specific input and output together. It is very important to understand the difference among analog cables so to choose the correct cable when it comes to routing and patching.
UNBALANCED AUDIO CABLES
Unbalanced cables are made of 2 conductors and 2 internal wires, one transferring the audio signal to its destination, and one transferring the ground signal that acts as both a reference point for measuring the voltage of that signal, and a shield that protects the signal from external noise to a certain degree, however the shield wire itself acts as an antenna thus capturing unwanted noise along the way, noise that is coming from electrical and radio interference especially from the power cables nearby.
The unbalanced cables transmit the audio signal directly to its source without any manipulation, thus transferring the noise with it resulting in a distorted signal in most cases especially if the unbalanced connection is too long. Unbalanced cables are good for connecting a guitar to an amplifier, or other low-level devices such as CD players, and they should be at most 6 meters long.
- RCA: Audio Cable used to transmit a Mono Unbalanced Signal, mainly to connect low-level gear such as a DJ Player to a Mixer. RCA originally stood for Radio Corporation of America, the name of the first company to design and produce electrical connector cables in the 1940s. This is also called Phono Cable
- 1/4” TS JACK: This cable has a Tip and a Sleeve. It can transmit a Mono Unbalanced Signal. Mainly used to connect low-level instruments with amplifiers (such as connecting a guitar to an amplifier)
- 1/8” TS JACK: This cable has a Tip and a Sleeve. It can transmit a Mono Unbalanced Signal. Mainly used to connect low-level audio sources with similar destination. This is also used in some Patch Bays or in Semi-Modular/Modular Synthesizers
BALANCED AUDIO CABLES
Balanced cables are made of 3 conductors and 3 internal wires, two signal wires and one ground wire that is also protecting the signal from external noise and interference. What makes a balanced cable special is that extra wire that is going to change the game of audio being transferred from the source to the destination, and that is canceling out the noise that is traveling along the way and delivering a noise-free signal.
The process is very smart. The signal being sent by the source is duplicated and inverted on that extra wire, meaning that both identical signals, occupying 2 wires, are going to create a destructive interference thus cancelling out the signal completely. Just imagine it as in mathematics, +1-1=0. Both wires are also going to capture noise along the way, so what you actually have in that balanced cable is nothing but noise being captured by both wires identically.
The trick is at the end of that connection, at the destination (the receiver such as an amplified speaker or a mixer that accepts balanced connection), where the signal on that extra wire gets inverted again to its original orientation, giving both audio signals a constructive in-phase interference that results in a louder signal, while the identical noise on both wires get out of phase and get canceled out completely. This is why balanced cables can run for 30 meters.
- XLR: This is a Balanced Audio Cable Mainly used to connect microphones to audio cards or mixers and amplifiers
- 1/4” TRS JACK: This cable has a Tip, a Ring, and a Sleeve. It can transmit a Mono Balanced Signal or a Stereo Unbalanced Signal. Mainly used to connect audio cards with studio monitors, synthesizers with analog mixers. etc..
- 1/8” TRS JACK: Also knows as AUX, This cable has a Tip and a Sleeve. It can transmit a Mono Unbalanced Signal. Mainly used to connect low-level audio sources with similar destination. This is also used in some Patch Bays or in Semi-Modular/Modular Synthesizers
A TRS Balanced Cable can transmit a Balanced Mono Signal or it can transmit a Stereo Unbalanced Signal. This is very important to understand here. Well, don’t get confused, let me explain..
Many audio sources such as some synthesizers (that output balanced signal), have a stereo output, meaning they can have a Left and Right outputs. Now, most of them have separate Left & Right output ports from the back panel. In this case, you need to plug a Balanced TRS Cable into each port and connect both cables to separate inputs of a mixer (Left & Right of a certain mixer channel), or simply connect them directly to a pair of speakers.
This is easy to understand, but some synthesizers can output a stereo signal however they only have 1 stereo port from the back that is going to transmit both Left & Right signals using only one cable. In this way, and depending on where you will connect this synthesizer, you have 2 options.
If the destination such as a mixer has a stereo input on one of its channels, then you only need one TRS Jack Cable to connect the single output port of the synthesizer to the single input port of the mixer (usually this channel on the mixer has a name that looks like this 5/6, meaning, one input port will occupy both channels 5 and 6 as it has to receive a stereo signal coming through a single cable).
In this case this TRS cable is going to transmit an Unbalanced Stereo Signal rather than a Balanced Mono Signal, and therefore the magic of inversion cannot happen because both wires inside that cable are going to transmit different signals, both left and right, and this becomes subject to noise of course.
If the destination such as a mixer has separate inputs (which is standard and usual), then you need a special cable here, one that has a TRS Jack on one side, and a dual TS on the other side, meaning, the cable is going to split itself into 2 connectors from the other side, both unbalanced TS Jack connectors.
So what happens here is that the stereo signal that is coming out of the synthesizer will then be split into 2 unbalanced mono signals (Left & Right) both having independent TS connectors that will be inserted into separate mono inputs on the mixer. This is similar to the headphones cable, on one side it has a TRS single connector, and on the other side it has 2 TS connectors both transmitting unbalanced mono signals (Left & Right)
TO SUM UP
Audio Cables are the veins of the studio or live setup. They play an important factor in determining the quality of the audio signal being transmitted from one source to its destination. Analog Audio Cables come in 2 main categories: Balanced and Unbalanced
- Unbalanced audio cables have a signal wire and a ground wire. They transmit a Mono Unbalanced signal to the destination as is, without any manipulation thus is subject to noise. Maximum recommended length is 6 meters
- Unbalanced audio cables are mainly used to transmit low-level signal such as a guitar to an amplifier.
- Examples of Unbalanced audio cables are RCA (Phono), 1/4inch TS Jack, 1/8inch TS Jack
- Balanced audio cables have 2 signal wires and 1 ground wire. The audio signal is duplicated on that extra wire and inverted (by the source) and then inverted again (by the receiver) cancelling out the noise in a destructive interference and passing a clean in-phase audio signal
- Balanced audio cables can transmit a Mono Balanced Signal or a Stereo Unbalanced Signal
- Examples of Balanced Audio Cables are XLR, 1/4inch TRS Jack, 1/8inch TRS Jack. Maximum recommended length is 30 meters