Whether in-wall, or mounted, builders need to wire for speaker locations based on the homeowner's listening experience.

Inevitably, it seems that doors, windows, and fireplaces are always in the wrong places when it comes to installing a home theater or distributed audio system in an existing room. It's as if the architects were concerned only with such trivial things as how the room connects to the rest of the house-and not with the really important things like how am I going to properly position my Dominator speakers.

Sure, you can build the "perfect" media room if you have the ability of starting construction from scratch. But often, builders and integrators have to deal with an existing room, such as a remodeling job or retrofit. The problem of "not enough places to put the speakers" was bad enough with 5.1 systems (five speakers and a subwoofer), but now we often have to set up media rooms for 7.1 systems (with two additional rear speakers).

To help builders with the dilemma of where to plan for speaker placements, and the wiring for them accordingly, here is some insight on how speakers should be located for the best listening experience.

The optimum position for all five or seven speakers in any given room is to place them all the same distance from the listening position. Fig. 1 shows the optimum placement for a 7.1 system. The front left and right speakers flank the video screen and the center channel speaker should be positioned on top of the television or on a shelf directly above or below it.

If you are using a projector for your video source, you will need a suitable stand to position the center channel speaker on the floor in front of the screen. In either case, the center channel speaker should be as close as possible to the screen so that the voices appear to come from the screen.

All Things Being Equal

Ideally, the Surround L and R (left and right) as well as the Surround Back L and R (left and right) speakers should be placed equidistant from the listening position. The circle in Fig. 1 illustrates this dimension. But unless you have a dedicated home theater room, good luck selling this arrangement to all members of the family.

If it is impossible to get the distances equal, don't worry. You can use the delay and level adjustment functions, available in most home theater processors, to compensate for the differences in distances. Just set the distance in feet to each speaker and the processor will delay the sound to make each speaker sound as if it is sitting in the right place. Then just set the volume of each speaker, using the test tone built into the processor, to be the same level at the primary listening position. This can be done by ear with some practice, but a sound pressure meter from Radio Shack for $50 makes it easy. A typical room, and speaker placement, is seen in Fig 2.

Mounting Speakers

One of the most common mistakes made in media room designs is in the mounting of the surround speakers in a 5.1 or 7.1 system. People have a tendency to hang them too high on the wall. Unless your client is Shaq, the proper height for hanging the side and back speakers is just above the listener's head, about 48 inches to the bottom of the speaker. This height will vary depending on the type of seating if you are building a designated home theater, or if you know how the homeowner intends to furnish a multi-purpose room. Otherwise, 48 inches will do fine. The subwoofer should be placed beside or behind either the left or right front speaker, usually in a corner of the listening room.

The In-wall Answer

The obvious alternative to all of these speaker boxes littering up your living space, is to use in-wall design speakers. Many manufactures offer very high quality in-wall speakers that are every bit as good, and some cases better, than the freestanding types.

If you don't build houses with circular rooms (and who does?), you will need to use the delay and level adjustment functions of your home theater processor to have the speakers sound like they would if they were sitting on the equidistant circle. See Fig 3.

Treating the Room

You now have to deal with room acoustics, to make sure the room has a relatively smooth sound. Start by making sure the room has wall-to-wall carpeting. Hardwood floors look great but sound, well, less than great. If you are dealing with hardwood or, worse yet, tile on the floor, try to use a large area rug.

Some rooms will still sound a bit too "bright" (noticeable extremes) even with carpeting. In those cases, at the decorating stage, you can use a soft decorative weaving such as a wall hanging to breakup the first reflections from the front speakers. The first reflections are the prime suspects in making the room sound too bright.

Fred Yando is vice-president of sales and marketing for Bohlender-Graebener, a leading manufacturer of loudspeakers for hifi, home theater and multi-room audio.