RICHER TIPS

10 Tips | Amplifiers | Bi-Wire | Cables & Leads | Compact Discs | DAB Radio | Digital Technology | Dolby Digital/DTS | DVD Player/Recorder | Essential Tips | Freeview and Satellite | Home Cinema Separates vs. All In One Systems | Home Cinema | Loudspeakers | Minidisc | MP3 | My First Hi-Fi | Plasma TV | Recordable CDs | Setting Up System | Stands

DOLBY DIGITAL/DTS

Got yourself a surround sound system yet? Well, if not you really have no right to call yourself a film buff. A decent AV system transports watching a movie at home from being an engaging experience to an amazing night-in that might just be even better than going to the cinema.

If you are thinking of buying an AV amplifier to place at the heart of your hi-fi/home cinema system you'll have noticed that many models now claim to be capable of delivering a bewildering variety of surround sound formats.

Until 1996 the only surround sound format for the home that was worth its salt was Dolby Pro-Logic. This was a four channel system that piped the sound out from your amp to five speakers - the front stereo pair, the centre dialogue speaker and a pair of mono rear effects models. Although it was, and still is a good system, Dolby and other companies realised that Pro-Logic could only really be a stopgap, and if the home cinema owner was going to keep pace with the exciting developments in cinema sound a new system would be needed.

In 1996 Dolby unveiled a new home cinema system called AC-3 which it later christened Dolby Digital. This has several key advantages over Pro-Logic. Firstly it is digital and capable of a more robust, more accurate performance than analogue Pro-Logic. Secondly it offered stereo rear surrounds. This might not sound like much of an enhancement but at a stroke it gave movie sound mixers the option of an effect buzzing seamlessly from one speaker to another. Thirdly it featured a dedicated bass output for a subwoofer - a pre-requisite for top cinema sound. In short it sounded far more exciting than Pro-Logic.

Originally Dolby Digital decoders were only featured on high-end AV amps, however these days all AV amps and receivers feature the processor, with prices often starting from below £150. Dolby Digital decoders are also built into many DVD (Digital Versatile Disc) players, and are worth considering if you have an older, non-digital AV amp or receiver - just check it has the required six channel RCA input.

Not long after Dolby Digital started being featured on AV amps, a rival surround sound format emerged. DTS is similar to Dolby Digital in many ways though its supporters argue it delivers a marginally more dynamic sound. These days the vast majority of Digital AV amps and receivers feature DTS in addition to Dolby Digital.

Following on from the original Dolby Digital and DTS, we have since seen the introduction of Dolby Digital EX and DTS-ES. These enhanced processors offer an extra rear channel in the case of 6.1, or an extra two side channels in the case of 7.1. As with the original system, AV amps and receivers featuring these processors are becoming ever cheaper.