Walk into any music store and look at the cables section. You’ll be faced with a dizzying array of instrument cables, speaker cables, microphone cables, midi cables, splitter cables, patch cables – so many cables that you leave the store more tangled than you can find. no matter which of them.
Although it can be overwhelming, analog audio cables can be divided into two main categories: those that transmit unbalanced audio and those that transmit balanced audio. Let’s dive into the details of these two, exploring the difference between balanced and unbalanced audio, and checking out a few examples of both.
Asymmetric cables
An unbalanced cable is made up of two separate wires: the signal wire and the ground wire. As the name suggests, the signal wire carries the audio signal from the source to the destination, while the ground wire provides a ground connection for the circuit to reduce noise.
As shown in the diagram below, the signal wire is sheathed with insulating plastic, around which the ground wire is woven. In this way, the ground wire acts as a sort of electromagnetic shield, working to intercept any radio frequency (RF) interference from reaching the signal wire.
Although made up of two wires, unbalanced cables are limited to carrying a single mono signal – for this reason, they are often used for mono sources like guitars or keyboards.
TS cables
TS (Tip Sleeve) cables use a ¼ ”connector, with two contacts – tip and sleeve. These are separated by an insulating ring around the connector body. These cables are standardized such that the tip carries the signal, while the sleeve connects to the ground wire.
TS cables are generally available in two versions: Instrument and Loudspeaker. Although the two end with TS “connectors, they use very different internal wiring and it is important not to be confused.
Speaker cables and instrument cables
Speaker cables are used to connect power amplifiers to passive speakers. As such, they must be able to carry the enormous amounts of current needed to power these speaker sets. Such high current requires sufficiently thick wires, lest you run the risk of setting the whole studio on fire!
If you were to connect a standard instrument cable from an amplifier to a speaker, you could not only damage the amplifier, but also start a fire. This is because the fine wire of an instrument cable cannot properly dissipate the heat created by such a high current and can ignite!
On the other hand, a speaker cable used in place of an instrument cable can cause unwanted noise. Unlike a standard TS instrument cable, a speaker cable is not shielded at all. Since these cables do not use a ground wire / shield, they are very susceptible to RF interference.
When used to connect an amp to a speaker, this is a non-factor, as the output of the amp is far greater than any potential noise, while the comparatively paltry output of a microphone of guitar can be easily overwhelmed by RF interference.
RCA cables
Another unbalanced cable that you may come across is the RCA cable. Named after the Radio Corporation of America, RCA cables are often found on the backs of older televisions, stereos, and recording equipment. Internally, RCA cables are the same as TS cables, they just use different connectors.
With the advent of HDMI and Bluetooth, RCA cables are largely phased out in the world of consumer audio, but they are still used in recording studios. When it comes to vintage gear that sounds great, few engineers would let a slightly outdated connector get in their way.
Balanced cables
Any cable, regardless of its shielding, will pick up some noise along the way. For sources like guitars and instruments, with relatively high efficiency and short cables, this noise is not a big problem. For microphones, however, this is a big deal.
The output of a microphone is paltry compared to that of an electric guitar, so using unbalanced cables is usually out of the question. So how do we isolate the audio we want and get rid of that noise?
This is where the balanced cable comes in: it is basically just two unbalanced cables that share a ground wire. With a little phase-reversal physics, we can not only remove the noise from the resulting signal, but also amplify the clean audio by a factor of two!
The balancing act
Imagine you have two wires, both carrying audio from point A to point B. When the audio enters the wires at point A, a component on the second wire flips the audio 180 degrees. In an oversimplification, think of this as a negative version of the first thread audio – the two will cancel out:
Traveling from A to B, both positive and negative audio pick up the same noise – for our good, let’s think of noise as positive:
Once the audio / noise concoction reaches point B, another component flips the second wire 180 degrees, back in phase. This turns negative audio on wire two to positive and simultaneously transforms positive noise on wire two to negative:
As a result, our audio forcibly doubles, while our noise cancels out completely! This is the theory behind balanced cables; it is this balancing of the audio that allows us to cleanly amplify weak output signals, without worrying about the noise that overwhelms the audio.
XLR and TRS cables
Common balanced cables you can buy are XLR (Microphone) cables or TRS (Tip, Ring, Sleeve) cables:
XLR and TRS cables are internally identical, despite having different connectors. That said, most microphones and microphone preamps are standardized for the XLR connection, which is why most stores will label XLR cables as “microphone cables”. TRS cables, on the other hand, are typically only used to connect professional audio equipment.
Wind the cables
Typically, unbalanced cables are used for instrument or speaker connections, while balanced cables are used for microphones and professional audio equipment.
Choosing the right analog audio cables can be confusing: knowing about balanced and unbalanced cables will go a long way in choosing the right cable for you. Analog audio isn’t the only place knowing cabling can come in handy – check out some of our other articles for more information on cables used for other types of media!
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