The Future Shop Comprehensive Guide to HiFi Cables and Accessories, Vol. 3 - Speaker Cables

Vol. 3 - Speaker Cable

This section of our guide is going to deal with what many people consider to be the central cable in a HiFi system: the speaker cable. This is the cable that runs from an amplifier to your speakers, and is the cable that generates the most ‘hype’ and the some controversy. But before we get into the materials and variables, it’s important to note something that we will repeat throughout this section- there is no ‘best’ or ‘perfect’ cable for every system. The right cable for you depends entirely on your equipment, and there will definitely be very expensive cables that will make your system sound worse. Before going out and upgrading your speaker cables, it’s vitally important that you have had your system for a little while and have an understanding of what you would like to improve about your listening experience. In an ideal world, you have addressed your power supply and eliminated as much ‘noise’ from your system as possible by allowing your power cables to burn in for up to 100 hours (which is a service we provide, for free, on many power cables). Now it is time to turn your attention to speaker cables.

So, what should you be looking out for on your search for the right cable? We are going to consider all the variables and how they can affect your experience.

Conductor Material

As we covered in the section on power cables, by far the most common materials used as conductors in HiFi and AV applications are copper and silver because they are the most conductive metals (as you can see above). Unlike power cables, however, there is greater scope for the use of silver in speaker cables. Cable manufacturers will use different combinations of these materials to take advantage of the effects they have on sound. Because silver is the better conductor, it tends to do a better job of conveying higher frequencies, whereas copper generally performs better with lower frequencies. This means that silver can tend towards a more ‘detailed’ sound, and copper a ‘warmer’ sound. Although silver is obviously more expensive, neither is objectively better, so what will suit you depends on the characteristics of your system and your personal preferences for sound. Used in a system that already provides a great deal of clarity, silver conductors could result in a ‘bright’, ‘brittle’ or ‘harsh’ sound. Conversely, an already ‘warm’ system with copper conductors could end up sounding muffled or lack dynamism. Every manufacturer has a different philosophy when it comes to conductors, so ultimately, the best way to decide on what sort of cable to buy will still be to call our expert advisors who will discuss your system, preferences and goals before making a recommendation.

Conductor Configuration

The logic that applies to the shape and configuration of conductors in speaker cables will be very similar to that of power cables, although for the most part the conductors will be a higher gauge (slimmer) than the ones used for power. Cheaper cables, like those used for outdoor installations or very long runs, will still often contain stranded conductors because of the increased flexibility that they offer. However, higher-end cables will invariably feature solid conductors of various gauges because they are less susceptible to the ‘skin effect’ or ‘strand interaction’- the term use to describe the interaction of magnetic fields created by conductors. Twisting the conductors is an effective way of mitigating the effects of their respective magnetic fields, as magnetic fields cancel each other out when the conductors cross each other at right-angles. For this reason many cables- both low and high-end- will twist the positive and negative conductors around each other to reduce interference. When talking about these strategies, cable manufacturers will often talk about ‘geometry’- this refers to the very specific way in which conductors and other components are arranged within a cable.

Dielectric

The dielectric in a speaker cable performs very similar functions to that of the dielectric in a power cable. They are still tasked with providing structure and minimising interference and energy loss. The reason the material used is important is that many materials will retain some of the signal passing through the conductor and then release it back at random intervals, which can affect the timing and detail of the resulting sound.

The ideal dielectric would be air, but this is not a practical (or achievable solution). PVC is a common material used for dielectrics, but it is not the most effective. Polyethylene is more common in higher end cables, and in order to benefit from the dielectric properties of air many manufacturers choose to use ‘foamed polyethylene’, which contains an amount of air which aids significantly in rejecting current. Teflon is widely considered to be the optimum dielectric material, and is used in many high-end cables. Some manufacturers will charge the dielectric with current so that it is ‘full’ and cannot absorb any energy from the conductor.

Dielectrics and shielding, perhaps surprisingly, actually account for a significant portion of the cost of high-end cables, as this is often where manufacturers are able to extract significant changes in the quality of sound produced- with a range of speaker cables from a single manufacturer at different price and performance levels, you may see the same conductor used throughout- it will be the other components which preserve the signal and improve performance.

Shielding

Shielding on speaker cables exists to protect the signal from EMI (electromagnetic interference), which any modern home is filled with. The two main types of shielding are: braided shields and foil shields. Both have their own advantages and disadvantages. While braided shields tend to be more flexible and durable, they are also unable to provide 100% coverage of the conductor. Foil shields, on the other hand, can theoretically provide 100% coverage, but are more delicate and require grounding. It is common to see a combination of both types of shielding on higher-end cables as manufacturers seek to combine their advantages and mitigate their weaknesses. It is also worth considering the materials used for the shielding, with

Length

The generally accepted wisdom on the length of speaker cables is that shorter is better. This is because the shorter the cables, the less opportunity for distortion, noise or interference to affect the signal. However, this is not an approach that works in every case. Some manufacturers will not produce cables at 0.5m or less because the technologies used in their cables (often ones concerning noise dissipation) need slightly longer runs to be effective.

While we would still recommend keeping speaker cables as short as possible, our main advice on speaker cable length is to keep the lengths of your cables to your left and right speaker as similar as possible. This is because drastic differences in lengths can result in issues with timing and therefore have a negative result on the performance of your system. Our advice is that the shortest run of cable should be no less than half the length of the longest run; e.g. if your longest cable is 5m, your shortest should not be less than 2.5, with this logic applying to left & right speakers and central speakers. You can get away with a greater difference on entry-level and lower-mid-range systems, but the effect would be more noticeable on high-end system so we would recommend keeping the runs of cable as similar as possible.

Plugs

An important thing to note when considering plugs for speaker cables is what the conductor in the plug itself is made from. Luckily, on higher-end cables manufacturers have usually thought this through and will use materials which have high conductivity for the core conductor and the plating material. On higher-end plugs, the core will usually be pure copper. The use of a substandard material in this application will undo much of the good work being done by the higher-quality wire that runs through your cable, and this applies to both the core conductor and the plating material. While gold is commonly used to plate plugs because it is not susceptible to oxidisation and considered a premium material due to its price, silver is the most conductive material, so could be considered to be a superior material for plating.

It is also worth considering the size of the plug itself- a very narrow plug may mean that the dielectric and shielding that run most of the length of the cable have to be stripped off to fit the conductor into the plug, meaning that the conductor is more exposed to interference. Better cables will feature wider plugs which allow the dielectric and shielding to be encased by the plug, helping to keep the conductor and signal safe from external interference.

Termination

There are four main termination methods used in most audio cables:

• Screwed connections- good connection, but the least secure due to the potential for screws to loosen over time.
• Soldered connection- very secure because the conductor and plug are welded together, but introducing different materials in the solder can affect the overall resistance.
• Cold-welding- creates an airtight seal and 360 contact between the plug and the conductors. This process is generally considered to be a superior method, but is not suitable for every conductor.
• Sonic welding- this is a relatively rare process, using high-energy sonic waves which are capable of joining metals together at the molecular level. This provides a seamless transition from conductor wire to plug, but is a very expensive process, and does not seal the plug around the cable, meaning that it will need to be used in conjunction with another method- usually cold-welding

Grounding

While not always considered important for signal cables as they do not contain an earth wire, many manufacturers have noticed the benefits of addressing grounding in some way as a means of reducing noise in a cable- usually through introducing an earth feature to their cable. This feature will only appear in higher-end cables, but has been proven to make a difference on high-end systems.

Once again, that’s quite a lot of information to digest but we hope it has been helpful in breaking down all the variables and letting you know what to look out for in the reams of technical information that many manufacturers provide. There is rarely a definitive ‘best’ thing in any of these categories, as it always depends on your setup, expectations and budget. Luckily, our expert technical advisors are able to take all of these things into account in a matter of minutes, so if you are looking for advice specific to you we would still suggest calling our Service Desk at +44800 772 3688 or +44208 905 1555.