Common Sense and Livability
No matter what we say here regarding room treatment and speaker positioning, keep in mind that a home theatre system is supposed to enhance your life, not take it over (unless you want it to). If any of our advice conflicts with common sense, your sense of aesthetics, or the normal function of the room, just ignore us. What difference does it make if your system sounds 5% better when you're always bumping into an ill-placed speaker? Do what makes sense.
General Home Theatre
If possible, place the five mid/high (non-subwoofer) speakers on the circumference of an imaginary circle whose centre point is your main listening position. At very least, left, right and centre speakers should be the same distance from your main listening position. Find the placement that makes the main speakers sound best, then relocate the other components (seating position, centre speaker/TV, and surround speakers) to fit the equal distance rule.
If you can make this work, fine. But if practical or aesthetic considerations get in the way, don't worry: the "time delay" or "speaker distance" function of your surround processor or receiver will compensate.
Stereo (Front L and R) Speakers
Since the left and right front channels are responsible for bringing music as well as movies to life, the stereo pair requires the most careful setup. For best performance, the speakers should be placed at least 60 cm from room boundaries, such as large pieces of furniture, walls and especially corners. Placing a speaker closer to room boundaries increases bass, but may result in a "boomy" or bass-heavy sound and degradation of stereo imaging. Try varying the speakers' distance from the rear walls, side walls, and corners until the best balance between low frequency extension and clarity is achieved. If your system has a subwoofer, choose a main speaker placement that provides the best imaging and most natural midrange balance, usually far from room boundaries. If you can't get the speakers at least 60 cm from the room boundary, treat the adjacent room boundaries with absorbing or diffusing material.
Place the main speakers at least a few inches in front of the front of your TV. Unless a large projection screen monopolises your wall, don't place the speakers too close to the sides of your television, as such placement constricts the width of the stereo soundstage.
Compact speakers are designed to provide good sound when placed on a wall and often come with wall mounting brackets. But, as with other types of speakers, you should avoid placing the satellites within 60 cm of side walls. Since wall mounting satellites precludes placing them in front of the TV screen, place wall mounted satellites higher than the top of the TV.
Further Placement Tweaking
To minimise the effects of standing waves, we recommend as a guideline the Rule of Odds. Measure the width of the front wall (the wall the front speakers are on) and the length of your room and divide any odd number (3,5,7,9 etc.).
For example, let's say your room is 3.5 m wide by 5 m long. Divide the room width by three and get 116 cm. Now divide the room length by 3 and get 166 cm. These calculations suggest placing the speakers 116 cm from the front wall, 116 cm from the side walls and 116 cm apart. For most people 166 cm is too far into the room and 116 cm is too close together to support a wide stereo image. Keep dividing your room dimensions by ever larger odd numbers until you come up with a placement that makes sense for you.
To continue our example, divide the length by 5 and you get 100 cm, a more workable distance. Divide the width by 5 and get 70 cm. So in this example a practical speaker placement that will yield good a result is 70 cm from each side wall and 100 cm from the front wall.
Always use the centre of the woofer as your reference point. If you calculate that your speaker should be 90 cm from the side wall - measure 90 cm from the wall to the centre of the woofer cone.
Avoid symmetrical placement. A speakers' distance from the front wall should not be within 33% of he distance from the side walls. For example if the speakers are 60 cm from the side walls, place them at least 80 cm from the front wall. In our example, we did not divide room length by 7 as that would have placed the speakers 70 cm from the front wall, too close to the 73 cm side-wall distance.
With floorstanding speakers, assume that the designers have mounted all drivers at the proper distance above the ground. Bookshelf and satellite systems, on the other hand, must be elevated to bring the tweeter to seated ear level, meaning the tweeters should occupy the same height as the listeners' ears when those listeners are sitting. This can be accomplished either by placing the speakers on dedicated stands, or mounting them on a shelf or wall bracket. If the shelf is well above seated ear level, use a door stop wedge under the back edge of the speaker cabinet to point the speaker slightly downward (be careful not to make the angle so severe as to make the speaker unstable). On-wall speakers often have brackets (supplied or optional) that allow aiming of the speakers.
Once the speakers have been properly positioned, they should be adjusted to provide the sharpest possible image. This is accomplished by a process known as toe-in. Your goal is to obtain the sharpest possible image by aiming the speakers at the listener, as if you were focusing binoculars on a distant object. Start with the speakers pointing straight ahead, while listening to a CD of a solo vocalist. Rotate each speaker a couple of degrees inward, toward the listening position, until the voice seems to come from a point directly between the speakers, rather than from the speakers themselves. But beware: too much toe-in will compromise the natural width of the soundstage. Try to find the best balance between image focus and soundstage width.
Your listening position will also influence the sound of your system. The best spot is at two-thirds of the length of the room. If that isn't practical, continue to divide by odd numbers as you did to determine speaker placement. In many rooms, the main listening position is on a couch up against the back wall. This position will yield very loud, and possibly boomy bass. In this case, be sure to place your main speakers and subwoofer as far away from wall surfaces as is practical.
Since the main purpose of a centre channel speaker is to fix all sounds associated with on-screen action to the screen, this speaker needs to be as close as possible to your television, either directly above or below it. Just like the stereo pair, the centre channel sounds best when its tweeter is mounted at seated ear level; unfortunately, this position is normally occupied by the television itself. No problem: you can achieve proper treble balance by tilting the speaker up (if it's below the screen) or down (if it's above) to aim the tweeter directly at the audience. Using rubber feet of different thickness, raise or lower the front of the speaker until you hear the most extended and detailed high frequencies.
Unlike the front three speakers that must produce sharply focused images, the job of surround channels is to envelop the audience in diffused sound known as ambience. To excel at this job, rear speakers should not (with the exception of localised 5.1 channel effects) call attention to themselves as sources of sound.
For these reasons, surround speakers work best when elevated at least 60 cm above the seated listeners' heads (a height of 1.8 - 2.1 m above the ground is considered normal), and mounted on the side walls in line with or slightly behind the audience. If you are using front firing speakers, they should face each other so that the sound is projected over the listeners' heads.
If your seating area adjoins the rear wall, or if you cannot place speakers on the side wall, you'll have to position the speakers on the rear wall. In this case, bi-directional (bi- or di-pole) speakers are recommended, since they will produce the most diffuse effect. If you use front-firing speakers, do not aim them at the audience as one would a front speaker, but point them straight forward so the sound projects past the audience. Another option is to mount in-wall speakers in the ceiling, aiming them downward at the listening area.
Low frequencies (below about 80 Hz) are non-directional, which means that, in theory, a subwoofer should sound the same whether it is located at the front, rear or sides of the audience. In reality, however, bass quantity and quality are influenced by subwoofer placement. As with the stereo pair, moving the speaker closer to room boundaries increases bass, while moving it into the room reduces output. For the greatest amount of bass output, place the sub in or near a corner of the room.
If you have a standing wave problem and the bass is very uneven throughout the room (especially at your listening position), try this old trick. Place the subwoofer at your main listening position (move the chair). Play a movie or CD with deep, sustained bass. Walk around the front half of the room until you find the spot with the best bass. Place the subwoofer there. Now you can have your chair back.
To some extent, you can compensate for room acoustics by adjusting the subwoofer's level control, but it's still advisable to experiment with various placements. Play CDs and movie soundtracks with extensive bass content, and fine tune the volume until you achieve a seamless blend with the main channels. If your sub is equipped with an adjustable crossover and your stereo speakers have sufficient low bass capability, try lowering the frequency to the 70-80 Hz region. Use the lowest frequency setting that combines powerful bass with the best stereo image and a smooth transition to the main speakers. Finally, use the phase control to maximise bass output: if your subwoofer is placed along the same wall as your front channels, set the phase to 0 degrees, if it is behind the listening position, try 180 degrees. It helps to hear phase differences if you sit in your listening position while a friend switches back and forth. As always, experiment until you find the setting that delivers the clearest and deepest response.