All speaker cables exhibit three main electrical properties: resistance, inductance, and capacitance. These three elements are mixed into the cables performance in different amounts. Resistance by definition is not welcome and should be kept at minimum levels. Resistance can reduce amplifier power and cause overheating. It also effects the damping capacity of the amplifier which controls the low frequency cone movement. It impacts amplifier output impedance along with loudspeaker input impedance. Both of these issues will impact upon timbre if there are issues with impedance and frequency.
Induction is not a good thing although not as bad as resistance. It will act as a low pass filter and influence the high frequencies in our signal. Inductance can also allow for penetration of radio signals into our amplifiers and thus our signal chain. There is a grating to sounds all through the frequency range with induction issues.
Capacitance is a type of enigma. If capacitance is large it has been known to cause amplifiers to become unstable. One may or may not be able to figure out that this maybe more of a function of the amplifier than the cable itself. One amplifier may be able to handle capacitance better than another amplifier. When designing a speaker cable, we definitely want the lowest capacitance we can achieve.
Shorter Is Better
When dealing with speaker cables, we all have heard that shorter is better. Speaker cables of long lengths create large issues. Lets take the example of an amplifier placed far away from the speaker. Our speakers have passive crossovers and are full range. This would be our worst case scenario. If our speaker cable is 30′ long, we will have signal loss and contamination.
Power Closer To Crossover
If we move the amplifier closer to the speaker’s crossover, we can help with this signal degradation. We can improve things further by running separate cables from the crossover to the low frequency and higher frequency drive units. This separate cable process handles full bandwidth and can be restricted to shorter cable lengths. Moving the crossover from the speaker is always a good thing. Speakers have magnets that do not play well with electric currents in our cables.
Low Frequency Energy
Low frequency energy within our cables is caused and created by larger amounts of current than our middle and high frequencies. This larger current requirement has its own artifacts and must be kept separate so that it does not impose any dielectric charge onto the middle and higher frequency lower current cable. Low frequency energy needs its own cable.
Bi-wired speakers cables that are connected to our passive crossover inside the speaker are another way to go if the inputs to the high and low frequency energy are separated. We then run separate cables from the high and low frequency inputs back to the amplifier. This separation is necessary to minimize the larger current requirements and their impact on cables.
The material to conduct our current whether for low frequency or high frequency has been a source of debate for years. Current cable technology even employs silver and aluminum. Silver has a smoothing quality to today’s high frequency digital information that can be bright and harsh sounding. Oxygen free copper appears to have sonic benefits over copper that is not so oxygen free. However, if cable lengths are kept at shorter distances, these differences are not so prominent.
The literature tells us that for 8 ohm loudspeakers we should keep our speaker thicknesses to 2.5 sq. mm or greater. This applies to middle and higher frequency energy carriers. Low frequency cables should be at least 4 sq. mm. At 4 ohm on the resistance of our loudspeakers, a 6 sq. mm thick cable would be required. If we increase the cable thickness and length, our cable will still keep the same resistance. However, our inductance will increase proportionately to the cable length.
No Fuses Allowed
We never want to place a fuse inside of a loudspeaker circuit. They do not possess constant resistance and can increase with temperature. In this scenario, the fuse acts as a limiter, increasing the series resistance as the drive current increases from the amplifier. The fuse also has a built in time clock if you will. The temperature changes in the fuse will always be lower than the current. Once the fuse blows, we have signal distortion.
Let Amplifier Protect
A carefully designed protection circuit inside the amplifier is the answer. Relays are not to be used because over time, they can have the resistance at the contact points diminish and change over time and use. If the contacts on the relays get contaminated, they can introduce a distortion into the signal path that is far removed from linear.
Synergy Of All Components
Resistance, capacitance, and resistance are the three main electrical properties exhibited by our speaker cables no matter consumer or professional. Make sure you are watching all of these variables when choosing a cable that is electronically compatible. Choose the correct cable thickness for the application of the cable. Make sure the electronic crossover is closer to the amplifier and keep the crossover out of the speaker cabinet. This critical feature has been overlooked in both today’s consumer and professional markets.
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