All you need to know about Speaker Cable

Made from multiple strands of copper wire that are encased in a plastic covering or insulation, and usually a pair (2-cores) that are identical. Speaker cable will either have the covering of those cores joined together, which is referred to as a ‘figure of 8’ cable (looked at end-on it resembles the number 8), or it will be two individual sheathed cores inside a second protective covering, which is known as ‘double insulated’.

They both do the same job, just that double insulated offers more physical durability so it is the better choice for professional applications. On higher current speaker systems it also helps to have the cores separated to combat heat buildup and inductance, and the single-rounded outer sheathing allows for professional connectors such as Speakon or Jack plugs to be used.

• Conductors

  This is the core of the cable, the flexible metal part inside the plastic outer coating. The conductors are usually made from strands of fine copper due to its excellent conductivity. Higher quality cables might use oxygen-free copper (OFC), which reduces oxidation and improves conductivity slightly, or even silver-plated copper for high-performance setups.

• Gauge

  This is a physical measurement of the cross-sectional area of the conductor. If you look at a cable end-on it will look like a circle within a circle, and the gauge is the diameter of the inner circle or conductor part. In the UK it's given in mm², such as 0.75mm² or 2.5mm².

  Depending on the source of your cable, it may instead use the American Wire Gauge system, or AWG, which is an imperial measurement of the total cable diameter. Most cable will actually state both for convenience.

  You will need to consider the physical limitations of the connection points on your specific equipment when choosing cable, as speakers or amps with push-style spring tag terminals can't accept a cable diameter much over 1.5mm².

  It is also worth noting that cable gauge is always given for a single conductor, so in the case of say a 1.5mm² speaker cable which is supplied as twin cable (for a positive and negative connection), this would be sold as 2x 1.5mm².

• Strands

  Speaker cables use stranded wire instead of solid-core wire. This improves flexibility and makes it easier to work with. Cable will often include the number of strands as part of its gauge rating, for example, 24/0.5mm² would mean there are 24 individual strands of 0.5mm² copper wire in each of the two conductor cores.

• Insulation

  The insulation surrounds the conductors and ensures that no electrical contact is made with other components, preventing short circuits. Common insulation materials include PVC, polyethylene, or Teflon, and different materials are used for a variety of reasons, from cost, flexibility, damage protection, and even specialist coverings designed to produce minimal smoke and fumes if burned (LSF cable).

• Polarity Markings

  Most speaker cables have some form of marking or colouring to distinguish between the positive (+) and negative (-) conductors. The copper cable itself has no polarity or directional requirements, but the markings help ensure you maintain the correct polarity of your speakers (i.e., making sure the speaker cones move in sync with each other) when connecting them to the amplifier.

When an amplifier sends an audio signal to a speaker, it does so in the form of alternating current (AC). The signal travels from the amplifier output through the cable’s copper conductors to the speaker's voice coil, which uses the positive and negative swing of the signal to create a magnetic field that opposes and interacts with the speaker's permanent magnet, resulting in a linear (forward and backward) movement. This action pushes and pulls the speaker cone in and out, producing sound by altering the air pressure in front of it.

The goal of speaker cable is to transfer as much of the amplifier’s output signal to the speaker as possible, using the minimum effort possible, without too much loss along the way. And by loss we mean exactly that, so, for example, let's say you have a measurement of 25V AC at the amplifier output and you connect a speaker to it with 10m of skinny cable, you may lose 1 to 2 volts by the time it's at the speaker due to that cables small conductor size and its high resistance. Double that length to 20m and you get even more voltage drop. You get the idea.

Using thicker cable means more copper, which gives you a higher current handling capacity and lower electrical resistance to significantly reduce this loss, and allow the amplifier to run at lower output which aids with both electrical efficiency and overall sound quality.

As a science bench example, you could take two identical amplifiers and matched speaker sets and connect one with 10m runs of 0.5mm² (20 AWG) cable, and the second with 2.5mm² (14 AWG). Feed the amps with the same source signal and turn both the amplifiers up to 50% volume. You will find the system with the heavier cable is significantly louder, with a fuller tone to its sound, with deeper bass and clearer treble. It’s a basic analogy, but the heavier cable is allowing the system to breathe easier, with more voltage reaching the speakers using less current from the amplifier, allowing them to convert more energy to sound while using the same settings.

The efficiency of the speakers also plays a significant part in that relationship, but that's going way off-topic. You can read more about speaker sensitivity and efficiency in our 'Guide to Matching Speakers and Amplifiers'.

You can use budget gear or high-quality audio equipment and it won't make any difference if you then compromise it with the wrong cables, as you are introducing a serious limitation into the circuit.

As just discussed, the thickness or gauge of a cable affects its ability to carry power over distance. Thicker cored cables can handle more voltage and current with less resistance.

Most home amplifiers and speakers will actually work with cable as thin as 0.75mm². However, it's generally recommended to go with either 1.5mm² or even 2.5mm² as the extra copper is so much kinder to the amplifier output and will provide a big improvement in sound quality, especially if running larger diameter woofers which require more current when producing low bass.

If you are dealing with PA amplifiers and speakers then it’s even more important to use decent cable, as it's highly likely you will be running this equipment at higher volumes and for extended periods. This is when poorly rated cables become hot and can cause serious damage to your equipment by affecting the loading to the amplifier, which will lead to all sorts of signal distortion issues and even amplifier output stage damage.

Low-cost stereo systems often include ‘free’ cable which many people hook up and use permanently, when in fact it’s only supplied to ‘get you started’. It’s common to see 7/0.2mm² - 24 AWG cable (bell wire) included which is both physically and electrically inadequate for this type of dynamic power connection. It’s easily damaged and will strangle the power delivery through its high resistance, causing the amp to work much harder, whilst lowering the available volume and frequency range.

Unless you are really into Hi-Fi and all the fantasy that comes with it, you will be buying speaker cable to be reliable and to provide you good quality sound without damage to your equipment. You should look at what’s available and what is recommended, and make an informed decision. You don't need the most expensive, but you also really don't want the cheapest either.

The chart shows the industry standard suggested maximum cable lengths for a range of speaker cable sizes on low impedance loads, calculated for 5% resistive loss. Ideally, you don't want to be anywhere near a cables maximum capability, so we always suggest going for the next gauge up. For example, the chart suggests 0.75mm² cable for an 8 Ohm speaker should be a maximum of 9.7m. In reality, if you need anything over 8m, its sensible just to go up to 1.0mm². It will give you better performance for a minimal cost difference and place less stress on the amplifier.

We will also mention here it may that speaker cables are only required for the connection between an amplifier and passive (non-powered) speakers. Active (powered) speakers operate with an internal amplifier to which their speakers are pre-connected internally. For active speakers, you will only require signal cables.

Speaker cables can come with various types of connectors at the ends depending if they are for home or professional use, though many setups simply use bare wire connections.

Some of the connection types you can find on speaker cable are:

• Banana Plugs

  Also referred to as 4mm binding post plugs, these are easy to plug into speaker terminals and ensure a secure, corrosion-free connection. They are popular with Hi-Fi enthusiasts and allow the use of a thicker cable that may have been too wide for a bare wire connection.

  The equivalent socket is a binding post. These accept the banana plug, or the socket body unscrews to allow the use of both spade connectors or a bare wire, making them a versatile option. You will find them on many good-quality domestic amplifiers and speakers.

• Spade Connectors

  These flat, forked connectors provide a more secure connection than bare wire and are commonly used in professional setups.The bare cable is crimped or soldered into the body of the spade.

  Spade terminals require either a binding post or screw terminals. Some Hi-Fi enthusiasts prefer them over Banana Plugs as they don't stick out the back of the amplifier.

• Bare Wire

  The most basic option, where the conductor is exposed and inserted directly into the speaker and amp terminals. Over time, however, bare wires can oxidise, which might degrade sound quality. Care must be taken during the connection of bare wire ends so as not to have any stray copper strands as these can cause shorting issues.

  Many lower-cost amplifiers and speakers will only accept bare wire as they are fitted with spring-loaded ‘push-in’ cable clamps, which will limit you to about 1.5mm² cable, though most equipment only offering those connections will be unlikely to be high-output so it will be fine.

• 6.35mm (1/4") Jack

  Found on many PA amplifiers and speakers, a standard mono jack connection offers a sturdy and durable connection and allows for thick cable to be used.

  The matching 6.35mm jack socket is a tried and tested design that's also found on electrified musical instruments, both for signal connection and for amp-to-speaker cabinet connections.

  It’s due to this fact that you must be vigilant when buying jack cables, and ensure you are using a proper 2-core speaker cable and not a single core with shield cable used for low-level audio signals, as these do not handle speaker level current well at all and are likely to melt.

• Speakon

  The industry standard for high power PA speakers and amplifiers. These large locking plugs and sockets come in both 2-pole (NL2) and 4-pole (NL4) designs for easy doubling of cable runs and interlinking of passive speaker rigs. They are usually found with either 1.5mm² or 2.5mm² cores.

  If you have the option for Speakon on your equipment you should be using it, as they offer the most secure connection and the heaviest-duty cable type.

• Conversion Cables

  It’s important to understand with speaker cable that the connector types are just for convenience and durability. What this means is they are interchangeable to suit different equipment.

  So for example you may have an amplifier that's best output choice is 6.35mm jack, while your speakers may have Speakon sockets. That’s perfectly fine, and you can either buy or make a cable with those specific plugs to each end. Just you ensure the positive and negative sides of the cable are correct into the plugs.