Updated 2015.03.04. 16,667 Previous Views.
There are a large number of different ways to connect components together. Let me outline them below: Video Connections first, then Audio.
Tip: Remember that audio and video signals flow separately (excepting HDMI & RF-Coax) and that you should typically use the "best" connection between any two devices for audio and video. It's often (but not always) best to connect "directly" from component to component rather than to go "through" another component. (The exception being an appropriate Audio Video Receiver) Sometimes you cannot go "through" a TV and retain the original audio signal - see the FAQ on DD5.1.
Most people have cable coming into their house either from the cable company, from a satellite dish, or from an antenna. RG6 is the better cable and you should use it where possible. RG59 is acceptable (between components) for short runs and is sometimes used where flexibility is required. RG59 should not be used however for connecting your satellite dish to your receiver as you will usually experience transponder / signal loss, use RG6 for this purpose (Note: many "patch" cables are RG59, not RG6).
RF-coax Cable is not however the best way to connect one component to another, because one component must "modulate" the signal to get it to the other component which then needs to "demodulate" the signal. This causes signal degradation. RF modulators in STBs, VCRs, DVD Recorders, etc are also usually mono, not stereo, so the connection will provide mono sound downstream of those devices.
Once a STB processes the signals, an RF-coax cable will not transmit HD signals from the STB to the TV. Do not use this type of connection from a STB (or DVD player) to an HDTV.
Composite Video Cable
(Usually Yellow, impedance 75 ohms)
Composite cable is the "video" connection that was the standard for many years. It's limited to SD signals of 480i). The luminance and chrominance signals travel "together" and this is therefore typically inferior to the next connections we’ll discuss. The composite connection can sometimes be better than S-Video (for analogue TV stations), if the "source component" has sent the signal through a comb filter, because the comb filter in your TV may be better at doing this than the source component. Try both and see which is better.
S-video connection is the next step up and usually supplies a superior signal to composite video, although it's still limited to 480i. This is because the chrominance and luminance travel separately. As mentioned before, the composite connection can sometimes be superior due to "quirks" of the various components hooked up.
(Red/Green/Blue Cables, Impedance 75 Ohms)
Component Video is the "best" analogue connection. The various video signals are "separated" as much as possible. 480P and High Definition signals require component video connection and cannot travel by any of the previously mentioned means from component to component. (Digital connections can also handle HD and they’ll be discussed next.) Component Video is limited to 1080P, however, the device' firmware usually limits the outgoing signal to 1080i
Note that component video is not the same as RGB (a connection used by some devices). These signals would require a transcoder for most devices.
Component Video cables, however, sometimes are not the best way to view SD signals from a STB. They can be sent via composite or S-video if the signals are not clear through component video cables. This is a known issue with some (older) STBs.
Some TVs have VGA ports for connection to a computer. Be aware that these may be limited to a different input format than the TV's native resolution - 768P vs 1080P for example. This is also a different signal from say component video.
DVI, HDMI and Firewire are recently added digital connections that allow you to connect one component to another (if they have the appropriate outputs and inputs) Firewire and HDMI connections will allow "two way" communication between components and this may be an advantage. Although these connections are digital, they do not necessarily provide a superior picture on your TV. Let’s say they are equivalent to component video cables and leave it at that for now.
HDMI is basically DVI plus digital audio in a smaller, but more fragile connector. DVI is not necessarily superior to component video - see the HDMI Comments/Issues FAQ for additional information on the topic of HDMI, especially how problematical it can sometimes be.
DVI can sometimes
carry audio if connected to a computer, but not a STB, DVD Player.
HDMI can be used to carry lossless audio (TrueHD, DTS-MA) from a BD player to an AVR. HDMI can handle signals up to 4K, but you need the correct version for that.
Audio cables are required when using composite, component, S-Video, VGA cables because those only carry video signals.
Analogue Audio Cables
(RCA, Red/White, Impedance 50 Ohms)
Up until about 20 years ago all connections were made with RCA cables. These cables (usually red and white) provided a means of getting analogue audio signals from one component to another, and still do. In some rare cases (and often on smaller HDTVs), the jacks on the back of the TV requires a "mini-plug" for the audio. In that case you'll need a stereo "Y-connector" to connect the red/white cables to. These cables cannot carry DD5.1 audio - optical or coaxial cables are required for that.
Toslink, or Optical Cable
Toshiba invented this method of getting digital audio signals from one component to another – hence the name. There is a modulator at each end that translates the signals from electrical to light and back.
Digital Coaxial Cable
(Orange, or sometimes Black, Impedance 75 Ohms)
(SPDIF - Sony Phillips Digital Interface - Toslink is also an SPDIF specification connection, which makes this confusing, but SPDIF usually refers to coaxial)
Sony/Phillips developed this coaxial connection as a method of getting digital audio signals from one component to another. People may argue whether Coaxial or Toslink is better, but let’s just say they are both excellent and better than analogue audio. For coaxial, you should get an "RCA-type" connection with an impedance of 75 ohms instead of the regular 50 ohm audio cable.
On some DVD players, especially for SACD, DVD Audio, or TrueHD on the new HD-DVD players, the audio decoding is done in the player and there are 6 or more analogue audio connections (outputs) required to transmit each of the channels. Your A/V Receiver would require the same inputs, otherwise you cannot "benefit" from these "superior" audio formats. Many people purchase/use 2-3 sets of component video cables for this connection - see below for more info. This is not used much any more.
(component video, composite, coaxial and subwoofer cables are basically the same with 75 ohm impedances, just different coloured connectors - yellow for video, orange or black for audio and various colours for the sub and Red/Green/Blue for component video)
HDMI can also carry audio from one component to another, however, older AVRs do not process the audio, simply switching the signal before it gets to the TV. See the HDMI & "If only..." FAQs for additional information.
Which Cables Should I buy?
This is the subject of endless debate, but here are my recommendations.
1. Buy a cable that has good connectors at each end.
2. Buy a cable at a price point that you’re comfortable with. A $20-30 cable is usually better than a $3 cable (when talking about analogue cables, but a $100 cable is not necessarily any better than a $20-30 cable.
3. A good cable is recommended for analogue connections.
4. For digital connections, especially short runs, almost any "qualified" cable will do the job, so there is not much need to spend "more" for a "high end" digital cable since the digital signals will either "get through" or they won’t. Again, buy what you’re comfortable with.
If you're thinking of purchasing expensive cables, please read the following:
Do I Need Luxury Cables? - Canadian TV, Computing and Home Theatre Forums
Lastly, about once a year or so, disconnect all of your cables, give them, and the inputs, a bit of a cleaning and reconnect them (rubbing alcohol and a Q-Tip work well). It’s also a good idea to "label" all of your cables once you’ve made all the connections, so that it’s easier to disconnect and reconnect as necessary.
For additional information, see the following link:
Video Connections Explained
Here's a link to a connections guide:
If you have any comments or suggestions for this post, please PM 57.