Wires for Audio

 

Audio wires can be divided into two groups: line level signals and speaker level signals. The line level signal is a low power signal used to transfer audio information from sources to amplifiers. Amplifiers output speaker level signals that drive the speaker themselves.

Line Level Signals

There are 4 common line level signals.

    • Analog "line level stereo" audio is the most common. It uses 2 wires to provide the left and right stereo signals available on most video content such as broadcast TV, CDs and DVDs. It uses RCA connectors or stereo jacks and one can be converted to the other easily.
    • Some DVD players also output 5.1 multichannel sound as line level analog audio. This is only applicable to disks that are using the SACD (Super Audio CD) or DVD Audio formats. Regular video DVDs do not use this format. Therefore, if your DVD player and AV surround receiver support 5.1 line level signals, you would want to wire these ports together, but you would also want to use one of the other signals listed here for the regular DVDs.
    • Digital coax (a.k.a., S/PDIF on RCA where S/PDIF stands for Sony/Philips Digital InterFace), which provides a high quality multichannel digital signal, is the preferred interface method for distances up to 10 meters.
    • Digital optical (a.k.a., S/PDIF on TOSLink) provides a high quality multichannel digital signal that can travel long distances over fiber optic cable.

 

In addition to the common line level signals above, occasionally you will see balanced line level signals which may use RCA phono plugs, ¼” phone jacks, or XLR plugs. Balanced line level signals can be used for sending high quality analog audio signals long distances, but this is pretty rare in most homes. Also in this group of non-speaker level signals you find the HDMI and TCP/IP digital signals that are discussed in the video section.

 

 

RCA

Digital Coax

S/PDIF on RCA

 

Digital Optical

S/PDIF on Toslink

 

Speaker Level Signals

From the output of the amplifier to the input of the speaker is the speaker level wire. This is an area of great debate, but there are a few things most people agree on.

    • The resistance of the wire vs. the resistance (impedance) of the speaker makes a difference. Toward this end, thicker wires have less resistance, and longer wires have more resistance. Therefore, the longer the run from the amplifier to the speaker, the thicker the wire you should use. Silver wire has lower resistance than copper wire so you can use thinner silver wires, but silver also costs more so you may end up paying more for the thinner wire. As you go from 8 ohm speakers to 4 ohm speakers, the resistance of the wire must be cut in half to maintain the same performance. Also, the resistance of the speaker may vary depending on the frequency of the music being played (i.e., the impedance is not constant over the audio frequency range). Therefore, it is important to match the resistance of the wire to the resistance of the speakers that will be used. Putting this all together, you may want to try to maintain the resistance of the wire at less than 5% of the lowest resistance of the speakers over the audio frequency range. For an 8 ohm speaker, use at least 20 gauge wire for runs of less than 20 feet and at least 16 gauge wire for runs up to 50 feet.
    • For runs less than 50 feet, some people believe that the capacitance of the wire can degrade performance in that when it is combined with the resistance of the wire it creates a low pass filter and limits the high frequency response. Others say that the capacitance of even the least expensive wire is not a factor in the audio range for relatively short distances. The former group would recommend low capacitance wire. The latter group would tell you that the 16 gauge power cord used to provide power to a lamp will produce the same performance from the speakers as the low capacitance wire.
    • For runs longer than 50 feet, most people will agree that the capacitance of the wire can reduce the performance obtained by high quality speakers in an acoustically ideal room. However, long wire lengths are typically associated with driving in-wall speakers in rooms that are designed for other purposes (such as kitchens and playrooms). For these applications, any 16 gauge wire may be fine. If you need a better quality signal, send a balanced line level signal or optical digital signal to the room and put the amplifier in that room.
    • People who buy more expensive speakers are usually more willing to pay more for the speaker wire. As the price of the speakers go up, the relative cost of the potential improvement in performance from higher quality wire may make it worth the cost.