Home cinema systems glossary
By Elisa Roberts
Understand the key features to look out for when buying a home cinema system, to help get the best sound quality, with our jargon-busting A-Z guide.
This helps get the best sound balance from your home cinema system. The kit bounces sounds from each speaker to a microphone placed where you expect to sit, measuring the ideal delay and distance for each speaker.
Digital audio inputs
If you want to hook your home cinema system up to another surround sound source, for example a Sky+ box, you'll need a digital audio input. There are two types - coaxial and optical - and both are capable of carrying a surround sound signal. Most separate receivers carry both; kits usually have one or the other.
Dolby Digital or AC3
The 5.1 multi-channel audio standard used on most DVDs and some digital broadcasts.
Dolby Digital EX
Dolby Digital EX takes the Dolby Digital 5.1 channel set-up one step further with an additional centre surround channel.
The original analogue surround sound standard, also known as Dolby Pro Logic.
Short for Digital Theater Sound, DTS also supports the 5.1 multi-channel audio standard. DTS is a competing technology with Dolby Digital. You'll find both types of decoder (Dolby and DTS) on most home cinema systems.
DTS ES supports a maximum number of 7.1 channels and adds one or two rear-centre surround channel speakers to the standard 5.1 setup.
The simple rule here is to save your money and buy the cheapest available. All HMDI leads have gold-plated connecting pins and Which? testing has shown that you will not see any data loss even when using the cheapest leads.
HDMI 1.4 is the latest standard for HDMI leads and offers improved functionality, such as an Ethernet channel which allows a 100Mb/s Ethernet connection between connected devices. It is also likely that you will need a 1.4 HDMI lead to connect and watch 3D films from your 3D Blu-ray player on your 3D TV. A 1.3 standard HDMI lead might work, but you’re unlikely to get the best picture quality.
The average power output is usually referenced as an RMS value and is often seen listed as ‘watts RMS’ on product packaging. The higher the output, the louder the system can go - but bigger doesn’t necessarily mean better. One of our Best Buys has a power output of just 16 watts, yet boasted some of the best sound quality when we tested it.
Some home cinema systems also feature analogue radio tuners, perfect for receiving FM and AM broadcasts. All of the surround sound amplifiers we tested have conventional radio tuners built in. You may see them referred to as surround sound receivers.
Most tuners feature Radio Data System (RDS), which shows the station name. Some models are more sophisticated and will even switch to travel updates when they are broadcast on other stations.
The Radio Data System, found in many tuners, supplies additional information for display. Kits tend to only offer a simple RDS function - the display of the station name. The RDS on separate receivers usually offers more information, such as the type of programme broadcast and scrolling text.
This is another name for an amplifier with a built-in radio or tuner. Those built for home cinema systems are called multi-channel receivers.
The smaller speakers placed to the rear and side of the TV.
Speaker cable length
If you're kitting out a large room, check that the cable lengths are sufficient for your needs. Cables to rear speakers, placed farthest away from the main unit, are especially important. Most separates don’t come with cables.
Speaker systems - 2.1, 5.1, 7.1
2.1 - For the clutter-conscious, these systems do away with the rear and centre speakers, leaving only the sub-woofer and two front speakers. They attempt to pull off a pseudo-surround sound effect with a mixture of electronic processing and audio conjuring tricks.
However, we have yet to hear a 2.1 system that can successfully mimic a proper 5.1 sound. Instead, they tend to produce a wall of sound, deep with bass.
5.1 - This has three front speakers, positioned to the left, right and centre at the front of the room, but also includes two rear speakers positioned behind the listener and a subwoofer positioned elsewhere in the room.
The lower bass notes that come from the subwoofer are less directional than the higher frequencies, so where you position it is less critical than the placing of the satellite speakers.
7.1 - A 7.1 system takes the basic 5.1 layout and then adds two more rear speakers. However, the majority of Blu-ray discs are only mixed for 5.1 audio so the addition of these two extra speakers has no significant effect. The number of 7.1 discs available will undoubtedly increase in the future, but uptake will be slow. The majority of people have enough trouble fitting six speakers in their living rooms, so the prospect of having to fit an extra couple in won’t be appealing.
7.1 is really only for the true home cinema enthusiast who wants the ultimate system and has a space and budget to suit.
The speaker that produces low-frequency sounds - specifically the ground-trembling bass. An active sub-woofer has its own power supply and amplifier and usually produces a better sound.
Some kits can play MP3 tracks directly from a USB memory stick, handy if you keep your music collection in digital MP3 format.
A great solution if the thought of all those wires snaking round your living room makes you feel faint. For the most part, wireless kits work in the same way as wired kits, but they have a transmitter that allows them to operate wirelessly.