Home Theater Wiring

Whether you are setting up a complete home theater system or just adding a new device to your existing setup, it can be confusing figuring out the best way to connect it all up efficiently while maintaining the best signal quality. Often there are several ways you can do things, so it pays to think carefully before you start your home theater wiring, particularly if you are going to buy cables which can be quite expensive. For example when I recently built a home theatre PC, I originally bought S-Video and  3.5mm stereo to RCA cables, intending to hook up the audio out via RCA and image via S-Video. Then I realised that the two inputs on the TV were on separate AV channels. Fortunately I got around it by doing what I should have done in the first place, which was to use a HDMI cable to carry both audio and video with great quality. In the end, the money I spent trying to do it cheap was wasted!

There’s a few different types of cable used to transmit audio and visual signals between devices. Some home theater cables handle both signals, while others are audio or visual only. Some of these cables can handle higher quality signals than others, and some are better for applications that require a longer cable between devices. With this in mind, lets take a look at some of the types of home theatre wiring out there, and the terminology you will encounter. We will also look at the steps you can follow when planning how to hook up a custom system.

Home Theatre Wiring Formats

Home theatre cable standards can be broadly divided into those designed to carry either analog or digital signals. An analog signal is one where the signal can have a range of different values, whereas a digital signal transmits data as either an on or off value (binary data). Examples of devices using an analog signal are CRT TVs, speakers, vinyl records etc. Devices that use digital signals include flatscreen TVs and computers (although these often have decoders built in to convert analog information to or from digital). If an analog signal needs to be carried over a digital format cable, it will generally need to decoded and recoded (converted) at each end. For example if you want to display an image from a home theatre PC on an analog screen, you need a way to convert the output to analogue – often requiring a signal convertor box if your PC doesn’t support analog output directly. Note that the conversion of an analog to digital signal, or vice versa, can introduce quality loss each time the signal is changed, with this being particularly dependent on the components used to translate the signal.

HDMI

HDMI is one of the newer digital cable standards. It carries multiple channels of uncompressed video and audio, allowing a single connection to carry data between a disc player and a home theatre receiver between any other digital input source and a TV, or anywhere that an audiovisual signal needs to be carried. HDMI also allows devices to communicate where supported, meaning that an output device can potentially ‘see’ a display device and work out which format to send – so your DVD player knows whether to send a 720i or 1080p signal to your  With HDMI, or in fact any digital cable, the quality and length of the cable can make a big difference to the signal quality. HDMI cables are rated as either standard or high speed based on their capacity with high speed being required to transmit full HD signals at a high refresh rate – for example a TV showing 1080p/100Hz would likely need a high speed cable. It’s worth noting that cable quality can vary though, and a lower quality cable might be good enough over a short distance. If you need to run a HDMI cable over a distance of more than 5 meters, opt for a high speed cable.

DVI DVI cables are designed to carry high quality digital video data. Although this format is mainly used for PCs, it does appear on digital TVs, and some other home theatre devices. DVI-HDMI converters can be used where needed without loss, but DVI does not carry an audio signal. Some DVI-HDMI convertors allow an audio signal to be ‘patched in’ so that the audio signal is carried over the HDMI cable as well.
Component Component is an analog video cable which provides a high quality image by splitting the color information into separate channels for red, green and blue. Component cables use RCA plugs, and are sometimes confused with composite cables for this reason.
S-Video S-Video is an analog video format. Cables commonly come with a round 4 pin connector that separates color and brightness into different channels. Although lower quality than component, it is generally considered to provide a better image than composite cable.
Composite Composite is an older analog format, but is still commonly seen as an input option for many devices. The familiar format is red, white and yellow RCA cables to carry left and right audio, and video.
Speaker wire
Banana plugs Unless you’re using a wireless speaker system, audio is carried to each speaker by paired speaker cable. Speaker cables vary widely in quality, with thicker wires often providing a better signal. Cabling materials make a difference too – copper wire is most common, but silver and gold can both provide better signal transmission for those with a very large amount of money to spend. Gold is commonly used for speaker cable connections. Longer speaker cable distances can cause some loss of quality, but at normal distances in a home theatre room this will often not be noticeable or even measurable. Speaker cable can be connected using several different methods, either bare wire cable ends that are clipped or screwed in or banana plugs, which can easily be wired up if your speakers require them.

Planning and putting it together

When it comes time to plan a home theatre system, it helps to sketch out the components you are connecting. Consider the output and input formats that each component has – this will tell you what cables you need. Opt for the highest quality at each step to get the best home theatre experience – for example if you have a choice of HDMI or Composite inputs on your new TV, do yourself a favour and use the HDMI! If you can minimise the length of cable needed wherever possible this may make a difference – it’s best to position your components first, and measure the distance between each to find the shortest cable you can get away with.