Home Theaters

The room, once chosen, that becomes the home theater, rarely has the proper treatments on the walls, floor, and the ceiling. By proper treatments, I am referring to sound absorbing materials that will allow the speakers to present more of the original sound and ambience, and less of the sonic signature of the room where the experience is being recreated.

There are different thoughts on sound treatments. While everyone agrees that trying to turn the home theater into an anechoic chamber is both silly and fruitless, as well as expensive, it is important to note that there are certain room attributes that need to be accentuated, and some need to be removed as much as is practically possible.

It is easy to get cues from quality theaters on setup, so that scientific principles can be followed, but scientific analysis is not needed. For example, theaters invariably have soft materials on the side walls, and rear wall. This is designed to absorb any early reflections. Early reflections are a problem because the direct sound from the speakers is what sets up the sound stage, and the ‘imaging’ that audiophiles speak of comes from the listener hearing the direct sound, without the reflected sound from the room surfaces competing and confusing the brain.

To treat walls and ceilings, an absorbent material, marketed under the name Sonex, is available for the ultimate in removal of early reflections, and can be sized for contouring the room response. Thinner tiles, with less pronounced ribbing, are used to absorb the highest frequencies.

35mm thick, this works well for ceilings and full wall covers. It is nice looking, and most significant others won’t mind the look - as long as you pick the right color - many are available.

Slightly thicker tiles are available, for more control, and are more useful when only a part of the wall is to be covered.

More pronounced ribs are better at mid frequency control.

For the really difficult rooms, or where sound control within the room is desired, along with external noise control, the thicker pyramidal shape tiles can be used, in thickness levels from 2″ to 4″. The largest of these will have sound control capabilities well down into the 2nd and 3rd octaves.

This is the big stuff. It will assert control over the most stubborn problems.

If you need real control, but no external noise abatement, or can’t stomach the pyramid form, this more sculpted pattern is available. Again - many choices of color.

For windows, covering the glass with something less reflective is important, more so on the side walls than the back wall. Heavy curtains will be helpful, but if really large glass areas are to be controlled, Sonex has flexible material, which can be hung like curtains, or embedded in a curtain.

Because this is dense, it will block light well, and further enhance the theater experience.

If, by some fortunate happenstance, your theater is large enough to have slap-echo problems, there are Sonex bass traps, designed to eliminate the problem.

Bass traps are to be placed in the corners of a room, and will control bass peaks, and slap-echo.

Most people will be dealing with a smaller room, and most will feel the need for more, not less bass. For them the bass traps placed in the rear corners of the room will help contour the bass yet allow the front speakers to take advantage of the low frequency augmentation that the corners will provide. As most know, where 2 room boundaries meet, a 3 db enhancement is provided in low frequency response, where 3 room boundaries meet (a corner), a 6db bump will be observed.

Should you, or the significant other, decide that this type of treatment is beyond what you want, there are low tech alternatives.

Thicker than normal carpet will minimize early reflections from the floor, heavy drapes will control reflections from glass, and if extended beyond the glass, will control hard wall problems. If further control is desired, a thin batting material can be employed behind a cloth-like wall covering. It will be less helpful than the Sonex, but will be vastly superior to bare, hard walls.

Remembering how the speakers need to be properly set up, and then positioning the sound absorbing, or sound controlling materials in their best places, will achieve much more of the sound field the movie production staff intended, and provide that much more of an enjoyable experience - better sound, and the satisfaction of knowing you set the room up for best sound yourself.

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(More later on room refinements, such as active equalization.)