When it comes to home cinema sound, true quality is in the ear of the beholder! Anthony Fordham presents a beginners guide to surround speakers.
No matter how much you spend on an high definition television, and no matter how big your display, there’s a reason they call this technology AV for ‘audio-visual’. That’s because audio is easily half the high definition home theatre experience, and having an incredible audio setup can make all the difference between so-so home movie viewing and mind-blowing entertainment.
Only the very top-end flat panel televisions don’t include a set of stereo speakers, but all home cinema projectors are vision only. Yet even if your TV does have speakers, and you reckon they pound out sound pretty well, a standalone audio system will always sound better.
The key to extreme audio is surround. Humans might have only two ears, but we’re still quite good at determining if the source of a sound is in front or behind us. We’re used to living in a world where sound surrounds us, and entertainment on a strictly stereo setup lacks that final immersive element.
In your home, a surround sound system does what it says: it surrounds you with sound. It’s a more natural way to listen and it really draws you in to the action. In sports: the crowd will be all around you. In concerts: you’ll hear the music bouncing off the stadium’s rear wall, and feel the energy of the crowd. In movies: you’ll hear cars roar past you, and feel the real power of explosions in action movies.
The best way to understand what surround can do for your system is to experience it: go in to a store and ask for a demo in one of their theatre rooms.
What is surround sound?
A surround sound system typically uses five speakers and a subwoofer (though you can have more). Each speaker in a surround setup has its own job, and needs to perform in a certain way to do it. Let’s take a look.
The centre speaker is placed direct under the televisions to ‘fix’ audio to the onscreen visual action. It carries the majority of a movie’s dialogue, and it has to project sound in such a way as to make that dialog crisp and not just audible, but comprehendible. And if your TV picks up a mono soundtrack, it will use the centre speaker.
Front left and right
Two speakers are placed in the traditional stereo position, either side of the TV. These front left and right speakers will do the lion’s share of work in any surround setup, along with the centre. Since most action in a movie happens in front of the viewer, most sound effects are mixed to the left or right front speakers. The way the front surrounds interact with the centre will have a profound effect on how easy it is to understand dialog.
Rear left and right
The rear left and right – or surround – speakers mirror the stereo pair either side of the television, but at the back of the room. Ideally, these are positioned at the seated viewer’s ear-height and behind the viewer’s line of sight.
These speakers provide the immersive ingredient to any surround setup. While most of the action will come from the front, secondary audio like crowd scenes or environmental noise (birds, ocean, wind etc) will be pumped through the rear, putting you in the scene. Elements of the soundtrack are also often mixed through the rear too, for extra immersion.
The five speaker channels provide the detail, but the sub provides the impact. Big, thumping bass hits you where you live, and sucks you further in to the action. It all provides the all-important bottom end for music, giving any performance that extra level of presence. What’s great about a sub is that your ear can’t tell where bass comes from, so you can place it anywhere. The role of the subwoofer can’t be understated either. It might be a big ugly box, but it’s worth having there: the extra bass lets you literally feel the action.
Surround sound formats
Speakers are not, of course, the source of surround, but rather the last stop in a chain of equipment that unlocks the multichannel soundtracks found on TV broadcasts, videotapes, DVDs and Blu-ray discs.
There are more than a dozen surround sound formats, but the two most common you’ll encounter are Dolby Digital and DTS. Both were invented for commercial cinemas (DTS stands for Digital Theatre System) but have since made the jump to your living room.
Both formats provide 5.1 channels of sound and have been around since DVDs were first introduced. To enjoy sound from all these channels you need five speakers and a subwoofer positioned around your listening room.
Dolby Digital and DTS have evolved since they first appeared more than ten years ago, and there are now dozens of different acronyms and versions and numbers and labels. Some iterations offer up to 7.1 channels of surround and require eight speakers in your living room, but good as this is, the sound is not high resolution sound; it’s actually less than CD quality.
When it comes to high resolution surround sound, there are two audio standards that are important for the very best experience: Dolby TrueHD and DTS-HD Master Audio. Found only on Blu-ray, these are as good as the original studio masters – accept no substitutes! There are others with ‘HD’ in the name, but these two offer the very best quality.
Previously, audio for movies was heavily compressed, similar to your MP3 player or iPod. This was so it could fit on a DVD. With high-capacity Blu-ray now in the market, the latest Dolby and DTS formats now offer multichannel audio at a much higher bitrate – and that means even better quality.
Of course, to support that quality you need a speaker system that can do it justice. Let’s look at the main options, in our article Surround sound – speaker options.