It just boggles my mind that I am still seeing homes wired for sound with wire that would barely ring a doorbell. These contractors have no idea what a disservice they are doing for their clients!
Audio signals carried over wire have to compete with some pretty nasty things. First there is electrical resistance; what you get out of a wire at one end is less than what you put in at the other. Audio systems and speakers work on AC (Alternating Current) power, in simplistic terms, the speaker pushes out (positive) and pulls in (negative) in order to make the music we all enjoy and the amplifier has to control this movement of the speaker. So, what ever length of wire is run to the speakers you have to consider that the electrical signal has to run through twice this length as the amplifier tries to push and pull the speaker attached at the other end. The best way to ensure that the amplifier has the best control of the speaker is by using a good conductor in the wire itself and by increasing the gauge or diameter of the wire. Good quality speaker wire will be usually made out of copper. Copper is one of the best metallic conductors of electricity, the only metal better than copper is silver. I can wire your house with silver wire but you don’t want to even guess how much that costs! Good copper wire will be rated at the percentage of pure copper in the wire – good wire, like Ivory Snow, will be 99% pure or better. That means that there are very few impurities in the wire that don’t conduct electricity. Most of these better wires will further state that the are OFC. That stands for oxygen free copper. This wire is formed in a vacuum so that air does not mix with the copper. Oxygen does not conduct electricity and you don’t want that getting in the way of your music, although it is good to breathe!
There are of course limits to how thick a wire you can use in any system, but the normal wire sizes, or gauges, of wire are from 18 to 10 gauge (the 10 being the thicker wire, I know it looks like we are backwards but that’s how the wire gauge measurement works). Of course there are limitations to wire due to cost (pure copper IS expensive) so most of the installations that we do at Wired 1 Consulting use 14 gauge wire, which is an ideal compromise between conductance and capacitive loss and most importantly, price. This wire is also made of multiple small strands of copper wire that make up the total gauge. The reason why you need to use stranded wire instead of solid core wire has to do with a nasty thing called capacitance. Not only will there be a resistive loss in wire but you will also get a bass loss (tinny sound) as this wire gets longer – now that really sucks! There is no way to avoid it other than to take steps to lessen it. Resistive loss you can counteract by simply turning up the volume of an amp but even the best equalizers on the planet will not properly correct for capacitive loss. Science to the rescue: Many years ago scientists studying signal transmissions in copper wire for the Trans Atlantic undersea telephone lines found that there was a difference as to where in the copper wire a frequency would like to travel. They found that the lower (bass) signals liked to ride on the outside of the wire, called the “skin effect”, and the higher frequencies (midrange and treble) liked to travel on the inside (core effect) of the copper wire – weird, but true! Which brings us to the reason for using stranded speaker wire and not solid core like your electricians wire your house with or use for doorbell wire! By having multiple strands of copper you give the low frequencies (bass) more area to run on the cable, thus lessening the capacitive effect that the wire imparts on the audio signal.
More to come…