November 11, 2008 The world of home theater seems ever changing. New formats, new innovations and cheaper prices have made an altogether bigger audio-visual experience more accessible for everyone. Two channel systems have been common place in our lounge rooms for decades now, but you might need a few more tricks in your arsenal to get the best out of the latest multi-speaker systems.
Generally you will only have five speakers, although these days a lot of seven-channel systems are making their way into peoples homes. A vast majority of DVD soundtracks will only have five channels of audio, like Dolby Digital and DTS. There are a handful of DVD’s with six channels in formats such as DTS ES and Dolby Digital EX but these aren’t widely used and there’s not many six channel AV receivers left on the market anyway.
That leads us to seven channel audio and new media sources like Blu-Ray and HD DVD. When setting up speakers for a five or seven channel system, there’s a few key things to remember. Firstly, sound, for the most part is directional, so keeping speakers at the same height is important. The general rule of thumb is to try and keep them at ear height, (when you’re seated) which is about a meter (approximately 3 feet). It’s no mistake that a lot of floor-standing speakers are designed at about that height. The problem is that many of us have our surround speakers wall mounted or installed in the ceiling, which is okay if they’re angled down towards the listener, but your ear will still notice where the sound is coming from. You’re better off if you can keep all your speakers on the same plane - reflection and cancellation of sound is less erratic and it helps them blend when trying to create an immersive surround sound environment.
Try to install any small speakers on stands to bring their height up (or down) to ear level. This will also improve bass response if good, sturdy stands are used. As far as placement goes, this all depends on how many speakers you want in your home theater system. As high definition sound is now available and here to stay, I would suggest a HD audio capable 7.1 channel receiver, should your budget permit.
A 7.1 channel receiver compatible with standard Dolby Digital and DTS formats is the next best step. Most of these receivers will be able to simulate surround sound information for the 6th and 7th speakers from the original 5.1 soundtrack.
Still, a 5.1 channel AV receiver and speaker setup is a cost effective, and more than adequate solution, if you aren’t planning on going down the route of Blu-Ray or HD DVD (any time soon.)
When locating speakers in a room, remember you are trying to create a “sweet spot” – the point where the sound from all the speakers converges - where you will be sitting. Many setup guides and diagrams indicate how many degrees off-axis each speaker should be and often suggest that they be toed-in towards the listener. (Refer figure 1 & 2.) These are an excellent guide, but the size of the sweet spot you are trying to create also comes into play. If you normally only watch movies with a group of family or friends, the sweet spot will need to be larger, in which case most of the speakers will need to point in towards the room, rather than toed-in towards one another and/or angled towards the listener.
The other thing to keep in mind is that a lot of us will also listen to stereo music on our home theatre systems. If you toe-in your front left and right speakers, you’ll create a rather narrow stereo image for music listening.
Subwoofer placement is not critical. Sub bass is of such a low frequency that the human ear is unable to pinpoint its origin, so it’s “felt rather than heard.” For this reason, a subwoofer can be placed almost anywhere in the room. Try to avoid placing it hard up against a wall or in a corner though as the low frequency will resonate readily through the structure of the house. This effect is largely unwelcome as it can make the bass dominate too much and sound muddy, so the key to placing your sub in the room is to simply experiment with what sounds right.
Lastly, more and more AV receivers and surround systems now have auto setup procedures. This usually involves a calibration microphone to be placed where the listener would sit (in the “sweet spot”) and test tones are sent out from all speakers to adjust levels and account for inconsistencies in the room environment and tonal differences from speaker to speaker, (which is particularly useful when mixing speaker brands). These auto setup features are a great idea, and achieve in minutes what would normally take an hour or so.
As home theater systems of all sizes find their way into more peoples homes, optimum setup and speaker placement often takes a back seat to aesthetics. So if you feel you could be getting a little more out of your system, consider where your speakers are placed in the room (not the decor). Creating an ideal surround sound field should go hand-in-hand with chasing the best picture as part of your home theater setup.