Cable thickness and working out what you need

Whether you’re looking for signal, speaker or power cables, the thickness and length are inextricably linked. In this blog, we’ll provide some information about cables and how they work. We’ll also give you a simple way to work out which thickness of speaker cable you need for an optimal signal.

Cables

A cable is essentially a flexible conductor and consists of wires that transport some sort of signal. There are many different types of cables and some are suitable for standard voltages, while others are built to handle higher or lower levels of power. Power cables are designed to transfer a current from one place to another. Audio cables do a similar thing, but they also aim to retain the quality of the signal and prevent external influences from affecting it. Interference tends to affect weaker signals more than stronger ones. That’s why a microphone cable that only carries a few millivolts is more susceptible to interference than a speaker cable that can handle 1000 watts of power. For that reason, microphone and instrument cables are very different from speaker cables.

Speaker cables vs signal cables

Depending on the type and thickness, speaker cables can handle signals of up to a few thousand watts, whereas signal cables, like those for microphones and instruments, tend to max out at about 5 watts. Signal cables have a small core that’s extremely well isolated to prevent external interference from getting to the wires inside and affecting the signal. Generally speaking, therefore, signal cables are not really designed to handle large amounts of power. There are different types of signal cables, however, that have different levels of conductivity and isolation. Naturally, the better a cable is isolated, the less chance there is of interference affecting the signal. A better conductor tends to ensure that a better quality of signal is transferred from A to B as well. These factors can make a real difference to the signal quality and can actually be heard in audio signals.

Cable thickness guide

When it comes to handling large amounts of power, like some speaker cables have to, cable thickness is very important. Large amounts of power generate heat and if a cable gets too warm, that can be a sign that the cable being used is not really thick enough for the amount of power that’s running through it. If this happens for too long, the cable can melt. For this reason, it’s important to be aware of how much power is running through a cable so that you can choose the appropriate thickness. These days, cable thickness is generally measured in square millimeters (mm²) although other less common methods also still exist.

Which cable thickness do I need?

Because this really only applies to speaker cables, we’ll only concentrate on them in this section. As you now know, the cable thickness is important when it comes to handling different levels of power, but one thing we haven’t really touched on yet is that the length of the cable is important too. This is because the longer a cable is, the greater the signal loss. Below, you’ll find a table with some examples of recommended cable length and thickness for different amounts of power.

Power	Length	Thickness
500 watts	10 metres	1.5 mm²
500 watts	20 metres	2.5 mm²
1000 watts	10 metres	2.5 mm²
1000 watts	20 metres	3.0 mm²

Longer cables are less capable of delivering the same amount of power due to more internal resistance. The table above takes into account a power loss of about 10% over a distance of 20 metres. While a 20 metre-long, 1.5 mm² thick cable has the capacity to handle 1000 watts of power without melting, more than 20% of the signal will be lost. This would affect the power output of your amplifier which is obviously something you don’t want to happen.

Also See:

> All cables