The argument about the quality of speaker cable or speaker wire has been discussed by audiophiles for many years and the topic is set to continue for many years to come.
Some speaker wire can be hugely expensive and some see this investment as worthwhile, whereas others see the cost as over the top and they would rather spend it buying a better amplifier or other item of equipment.
Speaker cable basics
The loudspeaker cable is the wire or cable used to connect the amplifier to the loudspeaker system.
Like all cables it has three main properties: capacitance, inductance and resistance. As a result of the environment in which speaker wire operates it is the resistance that is the most important. This is brought about by the relatively low frequencies used and the system impedance. Most speaker systems have an impedance of anywhere between around three or four ohms up to around 15 ohms. Today most loudspeaker systems have an impedance between four and eight ohms.
As the resistance rises it starts to affect the system performance. Obviously there can be a reduction in the drive current to the loudspeaker as the voltage across the cable increases. The other issue is that the back EMF created by the loudspeaker needs to have a low impedance source against which to work. As the source impedance rises, so the back EMF is absorbed less. This affects the performance of the loudspeaker, particularly in the bass region where the bass may not be as pronounced and it may sound less natural.
It is this change in the tonal quality of the loudspeaker that audiophiles tend to worry about.
Typically the effects of the speaker cable start to become noticeable when the resistance of the cable reaches about 5% of the speaker impedance. Some may even say it needs to be less.
Speaker cable make-up
The resistance of the speaker cable can be altered by three main elements:
- Length: The resistance of the loudspeaker wire is proportional to its length. There are two guiding principles:
- Keep lengths as short as possible: As the resistance is proportional to the length, it is obviously best to keep the lengths as short as possible. In this way the resistance is minimised. However the separation of the two speakers to provide the right stereo effect must be maintained.
- Keep lengths equal: The other guiding principle is to keep the speaker wire to both speakers the same and in this way they will both see the same resistance and the system will be better balanced.
- Cross sectional area: The cross sectional area or gauge of the speaker wire also has a major effect. The smaller the wire cross section, the higher the resistance will be.
- Conductor material: Copper is normally the conductor material of choice. It has a very good level of conductivity, it can be bent easily and the cost is quite acceptable.
Speaker wire conductor materials
There is a choice of a number of metals for use within the conductor of the speaker wire.
- Copper : Copper is the most commonly used material for speaker wire. Its cost is reasonable and it has a good level of conductivity, i.e. it provides a low level of resistance in the wire. However, copper does oxidise - the surface can become coated with a thin layer of copper oxide; this creates a high resistance barrier between the cable and the speaker or amplifier where the connection take place. Normally using screw pillars, etc breaks through the layer, but over time it can cause a higher than required level of resistance.
- Silver : Silver offers a slightly lower resistance than copper, but it oxidises. It is also considerably more expensive than copper. This means that a thicker copper wire will actually still be cheaper to buy.
- Gold: Gold has the lowest resistance and also it does not oxidise. However it is phenomenally expensive and as a result it is not used fort he wire itself. When it can be viably used is where the connections are made. Here a thin layer of plated gold can make a difference as it enables good contact to me made.
In general, the higher the level of purity of the wire, the greater the cost. Oxygen free copper wire can be very costly. Whether this actually brings any audible benefit is up to the individual to decide.
Bi-wire & single wire speaker cable
Apart from the material and insulation used in the speaker wire, there is also an option to use either what is termed bi-wire cable.
Bi-wire speaker cable is used when the speaker and amplifier have two sets of connections, one for bass and one for the other frequencies. Normally there is a cross-over unit in the speaker, but it can also be placed within the amplifier and in this way the bass and higher frequencies can have separate amplifiers, more tailored to their individual requirements. It is said that this gives a more open sound stage and increase levels of detail. Others say that single wire speaker cabling systems offers a more musically coherent sound. This is another discussion that audio enthusiast can debate for many years to come.
If the speakers have only one connection then this makes the decision straightforward. If the amplifier and speakers have a bi-wire system, then bi-wire speaker cabling, consisting of four parallel conductors can be installed.
Speaker cable cost / benefit
There are very many levels of speaker cable that can be used. Some cables can be exorbitantly expensive. Some manufacturers claim many improved properties and this can add significantly to the cost. Whether these benefits actually result in any audible improvement is debatable.
The most important element is the actual gauge of the wire. Often 4mm wire is thought to be the maximum anyone might want. 1.6mm or 2 mm is often thought to be more adequate for the relatively short runs found in most home systems.
4mm wire is very thick. As an indication, it has been reported that the Abbey Road studios in London (where the Beatles and many other top artists have recorded their music) has a very superb playback system and this uses 4mm oxygen free cable. Their cable runs will be quite long as they will need to go around the studio. Who would want any more than this?