HDTV UK's Guide to the Ultimate High Definition Home Cinema Experience - Part Four: The sound system
Getting the most from your high definition set up is not just about getting the picture right. Audio technology has also moved on significantly, and it's definitely worth considering a decent home sound system.
While high definition TVs and projectors generally give a great picture, they tend not to offer great sound (no matter what the specifications say) A decent surround sound (or at least stereo) system will fix that and ensure that your movies and music* sound good.
NB: It's worth noting that correct placement of surround speakers purely for hi-fi music is different than for home cinema. This guide deals with home cinema set-up.
All-in-one versus component systems
It's possible to buy all-in-one AV systems, with or without speakers, which can be a good choice if you're on a budget. However, it's rare to find a system where all the components are of an equally high quality.
It's generally better, though more expensive, to buy each part of the system separately. That way, you can pick the best manufacturer for each piece of kit, and upgrade pieces separately as budget or advances in technology require.
Stereo and surround sound technology
Audio technology has advanced a fair way in the last few years, with new high definition, uncompressed audio formats available allowing the closest possible reproduction of the original studio sound.
The absolute minimum set-up should include two quality stereo speakers. Some audio encoding systems offer virtual surround sound reproduction on just two speakers, which can be relatively convincing in a smaller room.
Common now are 5.1 channel systems, made up from a set of stereo speakers at the front of the room, two surround sound speakers left and right behind the viewing position, a central speaker placed above, below, or just behind the TV/projection screen, and a subwoofer which generally can be placed anywhere in the room.
Next up is a 6.1 channel system, which in addition has a centrally placed rear speaker providing additional surround sound.
A step up again is the 7.1 channel system, featuring the same as 5.1 channel system with the addition of central left and right surround speakers.
Above this is the so-called 10.2 channel system, developed by THX, which is allegedly "twice as good as 5.1" and supposedly as good as IMAX.
Generally, the larger, more complex setups will only really be of benefit in much larger rooms.
In addition, it's worth noting that these sound systems will only be fully utilised if all other hardware and software can drive them. However, an increasing number of high definition disc players, movie discs, and AV systems will handle the higher specification formats.
AV receiver
At the heart of the system is the AV receiver. It takes the audio and video from one or more sources (such as a DVD player, high definition DVD player, Sky HD box, or games console) and routes the required video signal to your display, and audio to the speakers.
It's worth bearing in mind that the raw specifications on power output can sometimes be "massaged" by manufacturers, particularly on cheaper units, to seem more impressive than they really are.
Generally, there's no point buying a system with a massive power output for a small room. Conversely, in a large space, you'll need a beefy amplifier to drive equally decent speakers so that the room is filled with sound.
Some receivers have additional functions such as upscaling of video, built-in DVD/CD player, analogue/digital radio, routing of more than one stream of audio and video, and so on. Bear in mind that these features will add to the price, and may in fact detract from the basic function of the unit — to provide quality amplification of sound and passthrough of video without degradation.
Many of these features are found in other auxiliary units in any case. Your TV or DVD player will likely upscale video as required, and, apart from the space saving, there's not much reason to have a disc player on the unit.
Speaker placement
Speaker placement is very important to achieving a good sound. In very basic terms, the following should be observed:
* The two front stereo speakers, generally which will be of the best quality, should be placed equally left and right of the central screen, angled towards the listener, with tweeters at ear height. Exact placement varies depending on the number of speakers in the overall set-up, as well as a degree of personal preference and room design.
* A central speaker should be placed either above or below the TV set, or behind the projection screen. This tends to be used to amplify vocals, and provide direct front sound.
* Two rear surround speakers should generally be placed high up, behind and angled towards the listener.
* Central surround speakers, if used, are placed equally left and right of the listener.
* The large subwoofer can generally be placed anywhere in the room, as it's hard for the human ear to distinguish the direction of these very low frequency sounds.
It's worth noting that some systems feature an automated home set-up system. Using microphones to measure sound output and direction, they aid in the correct speaker placement and volume settings.
For a larger room it may be worth going to a specialist dealer and seeing if they offer a home installation service. Though adding to the cost, the professional installation of a complete system will ensure the best possible experience.
Connections
Generally, it's worth connecting as much equipment to your AV receiver via digital links. The latest HDMI 1.3 specification will happily transfer both high definition video and uncompressed audio.
Many high definition hardware will operate via HDMI, so it's worth ensuring that the AV receiver has plenty of inputs — at least three.
Equipment with only DVI outputs will need a separate audio connection to the AV receiver, as DVI doesn't handle audio.
Analogue and/or standard definition equipment will need to be connected using analogue connections.
Generally, the AV receiver output is then connected to the TV or projector's video input, while audio is routed to the speakers using good quality copper cabling.
Budget
Not surprisingly, AV receivers and speakers can cost a serious amount of money, from a few hundred pounds to several thousand pounds.
Advice that I've heard is that it's worth spending a decent amount of money on the two front stereo speakers, regardless of what other surround speakers you add, and that it's not worth spending more than twice the cost of those speakers on the AV receiver.
Of course, that's a very rough guide, and brand name and additional features will affect the cost.
Generally, decent systems come from the likes of Denon, Sony, Onkyo, Pioneer, and Yamaha. As always, test out the systems in the best sound environment you can before purchase, if possible.
Conclusions
* Good high definition sound complements good high definition video, so it's worth investing in a decent sound system to go with your HDTV or projector.
* Budget systems often boast inflated power ratings, making it hard to compare based on raw specifications. Let your ears be the ultimate judge.
* Don't skimp on connections, particularly from AV receiver to speakers.
* Get advice on the best system for the size of room you're installing into. A small room doesn't need a massive system, while a large room requires something with much more clout.
* Beware of the "bells and whistles" which could detract from the overall sound quality or simply add to the price, while being superfluous to requirements.
* Ensure the receiver has enough HD-compatible input and output connections, preferably HDMI 1.3.
* If budget allows and you're fitting out a large, dedicated home cinema room, consider professional installation, or at least a system which aids optimal speaker placement.
* If you're looking to work with the newer, uncompressed high definition audio formats, ensure both your AV receiver and all other components can handle them. Expect to pay more for this top end feature.
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