Controversial and important: the boring science of speaker cables.
Here’s a question for you: What is the oldest profession in the world? Nah…not what you think: it is the cable guy! How else did God get the light to go on that very first day of creation?
Now that I have your attention and all joking aside… a factor that is commonly overlooked in choosing wiring is the material that the wire is made from. Copper and aluminum are the most commonly used wire materials and there is an important difference in quality, power handling and signal transfer between these materials.
The least costly between these 2 options is Copper-Clad Aluminum (CCA) wire. CCA wire utilizes an aluminum core that is clad or dipped in copper. It is a suitable choice for lower powered systems or restricted budget applications, although the power transfer is not on the same level as the alternative Oxygen Free Copper (100% OFC; OFC wiring is refined to remove virtually all oxygen and other corrosive elements.) wiring.
Compared to OFC, Aluminum wire is more brittle over time and can result in a short in a home wall if the cables are not handled carefully. Sharp bends, extreme force during pulling of cables can break strands within the wire. If you decide to opt for CCA, we strongly advise to test your CCA cables before you close down the wall and put the plaster boards up.
Oxygen Free Copper wiring provides a better electrical conductor to aluminum because it does not expand or contract with heat and can carry a higher current load. The improved efficiency of OFC wiring will also allow your sound system to run at its maximum efficiency. OFC is less prone to oxidizing in the jacket close to cut ends or where the copper comes into contact with the air. Oxidation will look somewhat similar to a rust like yellow-brown color and it will inhibit the wires ability to carry audio signals as well as it once did when new. This will in turn degrade the audio signal and make your amplifier work harder than needed and also increase voice-coil heat in your speakers which degrades audio output as well. But of course, this superior performance of OFC wire comes at a price. OFC is about ten to fifteen times more expensive compared to CCA.
If you decide to use CCA, ensure a minimum of 16 or 14 AWG wire only, just to make sure. AW…what? AWG stands for American wire gauge, it is a standardized wire gauge system used since 1857 for the diameters of round, solid, nonferrous, electrically conducting wire.
To make things interesting, they decided to make the higher number AWG the smaller diameter of wire. For example, 16 AWG cable has a diameter of 1.31mm2 whereas 14 AWG has a 2.08mm2 diameter. Oh, and the famous kiwi “number 8 wire”? That would be 6 AWG.
When you install speakers, be it in wall, in ceiling or floor, the distance between your amp and the speakers will determine the minimum AWG required to make sure that your amplifier can send enough current to your speakers (so they perform at ideal power).
A little table will help you choose:
|Speaker Impedance||8 Ohm Load||6 Ohm Load||4 Ohm Load|
|Wire Gauge||Distance (m)||Distance (m)||Distance (m)|
The geeks may ask: so what about insertion loss and damping factor? Talk to Nick and Bart at Rapallo and we’ll have a chin wag about that one 🙂
Tha Rapallo Team