Connecting your AV system can be confusing, especially if you don't know your composite from your coaxial. As diverse as the devices in your system are you'll often find that the means of connecting them is even more varied, so before you get yourself connected, use this guide to find out what's what and where it goes.
Video connections
As the name suggests, these connections are used to carry video signals between your source, such as a DVD player, and screen. Video connections can be either analogue or digital and follow a hierarchy of performance, starting with:
Composite
While composite is the most common analogue video connection in home cinema it's also the lowest quality connection and is best avoided if you can help it.
The connection uses a single coaxial cable to carry a combined video signal containing luminance, hue and saturation data that's fitted with an RCA plug at the end and typically coloured yellow.
Poor picture quality is a symptom of carrying all elements in a single cable and images often suffer from washed out colours and fizzing images.
Advantages: Universal compatibility
Disadvantages: Poor picture quality
S-Video
S-Video stands for Super Video, a standard developed by JVC almost two decades ago that's still common among sources and screens today.
The single cable connection consists of four round metal pins and one rectangular plastic one - that can be frustrating to fit. S-Video offers improved performance by separating the video signal into luminance and chrominance.
S-Video doesn't improve picture resolution but does enhance colour resolution for a richer, more refined picture.
Advantages: Improved colour performance
Disadvantages: Fiddly connections; poor resolution
Scart (RGB)
Scart was originally known as the Euro Scart after being developed in France and eventually becoming adopted throughout Europe - although it's still pretty much ignored by the rest of the world.
The oddly shaped connection holds 21 pins that each carry a signal - with some pins acting as inputs and others as outputs so the connection works both ways. However, not all the pins are always used, with some Scarts only carrying basic signals and others only carrying video signals. Fully wired Scart cables carry both video and audio signals offering the convenience of a single cable. And Scart cables can also carry data signals with uses such as instructing your TV to automatically adjust its aspect ratio.
Fully wired RGB (simply Red, Green and Blue - where three colour components of video are carried separately) Scarts provide one of the finest analogue video connections with excellent detail and colour resolution. However, many products only carry a single RGB Scart connection (that should be used for your most used video source), forcing you to compromise with other components.
Advantages: Versatility; carries video and audio; excellent picture performance
Disadvantages: Not universally accepted; no progressive scan video support
Component
Component (often marked Y, Yb, Yr or something similar) is the finest extended definition analogue connection available and, subsequently, the connection of choice for home cinema enthusiasts.
Component connections appear as a set of three coaxial cables carrying a single luminance and two phase-opposite chrominance signals with different Red, Green and Blue colour markings. Component connections can accept high-definition, interlaced video signals up to 1080i and also support progressive scan video provided you have compatible equipment.
The picture is detailed, smooth and free of noise, especially using progressive scan mode, and comes close to cinema quality.
Advantages: Outstanding picture quality; supports progressive scan video
Disadvantages: Not digital; doesn't carry sound
HDMI (High Definition Media Interface)
HDMI was developed by several of the world's largest consumer electronics companies and has become the standard digital interface for home cinema. HDMI-equipped products are still limited - but that's changing.
The single, compact interface can support both uncompressed digital video, up to eight channels of audio, and device control data used to integrate assorted equipment into a unified system. There are few demands on cable length, with runs of over 50ft possible without signal degradation. And HDMI is also compatible with components which use DVI as standard via an adapter.
Picture performance is peerless with amazing detail, depth-defining contrast, cohesive movement and virtually no picture disturbances.
Advantages: High-definition video and audio in a single cable; outstanding performance
Disadvantages: Still relatively rare
DVI (Digital Video Interface)
DVI was originally developed to connect computers to flat panel monitors but has found applications in home cinema where it's used to transmit digital video signals between source and screen.
DVI connectors look like computer VGA leads, only larger. There are three types of DVI connection - DVI-A designed for analogue signals and only used with computers, DVI-D designed for digital signals and DVI-I designed for integrated analogue and digital signals. DVI-D is the most common format used in home cinema and carries uncompressed digital video providing a higher quality and faster interface than analogue alternatives. DVI-I can also be used as it supports DVI-D cables even if analogue transmission is never used. One disadvantage of DVI is that it's limited by cable length with runs over 20ft affecting image quality.
Like HDMI, pictures are amazingly accurate with deep black levels creating detail and contrast far beyond anything an analogue connection could manage.
All-digital video connections are still relatively rare in both sources and screens alike, but that's changing, and connections like HDMI and DVI represent the future face of AV connections. All-digital connections allow the direct transmission of digital signals without conversion between analogue stages to produce images of outstanding quality.
Advantages: All-digital connection offering outstanding images
Disadvantages: Limited cable length; doesn't carry sound; still rare
Audio Connections
Audio connections are used to carry sound signals generally between a source and amplifier. Analogue connections are mostly limited to stereo applications while digital connections can carry several channels of sound.
RCA Phono
RCA phono, developed by Radio Corporation of America (RCA), is the standard analogue audio interconnect found in most AV products.
The single, plugged cables are used to carry analogue audio, supporting either mono or stereo sound. Non-digital stereo sources typically use a pair of colour-coded interconnects to separately carry the left (white) and right (red) channels.
Sound performance is dictated by the quality of connections used and upgrading your interconnects is one of the easiest and cheapest ways to improve your system.
Advantages: Simplest analogue audio connection; inexpensive
Disadvantages: Doesn't support digital components; limited to stereo only
Coaxial Digital Audio
Otherwise known as SPDIF (Sony Philips Digital Interface), coaxial connections are the standard for carrying high-quality digital audio without the need for analogue conversion.
The double-shielded, solid conductor cables are identical to composite video connections and can carry either stereo or multichannel audio signals. When coaxial connections first arrived they were believed better than optical digital connections but advances mean there's little to choose from between them - although coaxial cables are seen as more robust.
Coaxial digital connections offer improved resolution, although the copper elements used in the construction can be prone to electrical interference.
Advantages: Digital connection supports all digital audio signals and surround sound formats; extensive compatibility; robust
Disadvantages: Can be prone to electrical interference
Optical Digital Audio
Also referred to as TOSLINK (Toshiba Link), optical digital connections use thin fibre optic cables to carry digital audio signals supporting stereo and multi-channel sound between components.
The cables have a fiddly TOSLINK connector at either end and the quality of the interface, with some cheap cables using fragile plastic conductors, can lead to damaged data and affect performance. Many people believe optical connections use a laser when in fact it's an LED light.
Performance is impervious to electrical interference but optical connections are limited by cable length (up to 20ft) and bending the cable can cause internal reflections and signal loss.
Advantages: Digital connection that supports all digital audio signals and surround sound formats; free of electrical interference
Disadvantages: Limited cable length
FireWire
FireWire is a true all-digital audio connection that's also known as IEEE1394 or i.Link (Denon has its own version called Denon Link). It's most commonly used in home cinema as a multichannel audio interface to support digital sources, transferring data at a very high rate. Video applications are available but are largely limited to digital camcorders.
Single cable FireWire connections for home audio applications usually have six-pin connectors at either end and carry audio signals with virtually no signal loss. FireWire connections are still only found in a few high-end components. But the numbers are growing.
Not only do FireWire connections offer the convenience of a single cable but the lack of signal deterioration means sound quality comes close to the original recording.
Advantages: All-digital connection; tremendous bandwidth; single cable
Disadvantages; Still relatively rare
XLR
XLR is a specialist connection used in high-end and professional audio equipment. It's sometimes referred to as a 'balanced' connection where positive and negative wires are separately shielded to prevent interference from external noise.
XLR connectors are circular with three pins and the balanced design helps eliminate noise and hum, especially when used with pro microphones and PA amplifiers.
Advantages: Balanced connection impervious to external interference
Disadvantages: Not in common use
DIN
DIN (Deutscher Industrie Normen) is a European standard connection used as an alternative to RCA phono that's found in some specialist, high-end audio equipment and computer systems.
DIN connectors look similar to S-Video connectors with five pins. DIN connections don't reflect the audio signal like RCA phonos, improving performance, especially with harmonics and background instruments.
Advantages: Audiophile quality sound
Disadvantages: Limited to a few products; comparatively expensive
BNC
BNC connections are another alternative to RCA connectors that are found in some plasmas, projectors and high-end audio equipment.
The connector simply turns and locks to stop cables from coming loose. You can connect standard RCA cables using an adapter.
Advantages: Solid connections that don't come undone
Disadvantages: Limited use
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