Digital and Analog Audio Video Cables Explained

As consumer electronics have evolved over the past 50-60 years, a plethora of cables and connections have evolved to interface them. It can be a little confusing. Here is an overview of the audio and video cables used to connect all kinds of electronics that will help you understand what is going on the next time you need a hook-up. What’s in an Audio-Video Cable? There are three components in a cable that affect signal quality: the conductor, the shielding, and the connector. The conductor is the type of material used as a medium through which the signal passes. Different conductors have different properties like resistance, and techniques like twisting affect these properties. Excess length and inadequate diameter for the signal are common conductor issues. Since a conductor is also basically an antenna, it can also pick up other signals. Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI) introduce noise signals into the desired video or audio signal. Proper shielding on a cable reduces electronic noise that the conductor receives. Every connector on a cable actually makes two connections – the connection to the equipment and the connection to the conductor. Bad connections on either side can mean serious degradation of the signal and are a common source of quality issues. Technical performance information is usually readily available when shopping for cables. You don’t have to become an expert, but by learning some basic terms and understanding what is good and what is bad, you can prevent greatly overpaying for a not-so-great cable (which is easy to do). Analog Audio Cables The ¼ inch plug connections (male and female) commonly known as RCA or phono jacks have been around from almost the beginning of the component stereo era. They are still a fairly common way make audio connections between components. A separate connection is used for left and right stereo signals, so connections are usually color coded in red, white, or black. As video became part of home electronics, the RCA jack was employed to connect video signals as well (color coded yellow). While great for analog audio, the RCA jack is less than ideal for video. However, it was adequate when the common format for video was VHS tape. Digital Audio Cables Only recently have cables used only for digital audio started to become common. Digital audio signals are frequently combined with digital video signals (as described with HDMI), so separate cabling is not needed. The most common type of digital audio connection is the Coaxial Digital Audio cable. This uses an RCA connector on each end with a coax cable. Since both audio channels are transmitted digitally over one wire, only one cable is needed for both channels. Since coax cable is used, Coaxial Digital Audio cables feel and look more substantial than RCA cables, plus the connector is frequently plated with a fine metal to improve the connection. Optical Digital Cables use fiber optics to transmit digital audio signals as pulses of light. While this may be the optimal way to transmit digital information, optical cables are expensive, can be somewhat fragile, and have bending limitations. On the positive side, optical cables are immune to interference and do not degrade over a long distance. Analog Video Cables There a number of cables used to carry analog video signals. As mentioned, a common RCA jack was typically employed early in the life of consumer video equipment. As the mediums used for video improved, from enhanced analog like Hi-8 to digital like DVDs, better connections were needed. Options for analog connections and cables include: RCA (Composite) Coaxial S-Video...

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