Subwoofer Placement
Room Treatment
are all behind the listeners, creating a big “hole” in the soundfield between the front and the back.)
a 7.2 channel system layout
Subwoofers offer somewhat greater flexibility in placement, since the frequen- cies they reproduce are not readily localizable by the human ear. This is due to the fact that the wavelengths they reproduce are more than ten feet (3 meters) long, but our ears are located only about
However, this fact does not mean that the placement of the subwoofers has no effect on the sound quality in the room. Far from it. The subwoofers are the most likely to suffer from the response irregularities introduced by the room itself, operating as they do below approximately 80 Hz in most systems.
Recent research into the behavior of rooms as a function of speaker placement has concluded that — if you have the freedom to do so — there are significant advantages to placing several smaller subwoofers around the room, rather than relying on a single large woofer. Moreover, the optimum placement is usu- ally centered on each of the four walls. If you have the luxury of doing so, this simple placement strategy can reduce the size of the room’s response irregulari- ties from 20 decibels down to perhaps as little as
Reducing the room’s inherent problems to this degree is a huge advantage. It allows the
Rectangular rooms have six reflecting surfaces (four walls, ceiling and floor) that reflect sound to the listener, after various delays introduced by the indirect routes the sound waves take on their way to the listener. These first reflec- tions are particularly damaging to sound quality. Looking at the simplest case of stereo reproduction, you have a minimum of twelve first reflection points in your room that deserve some attention.
Unfortunately, it is often difficult to do much about the ceiling and floor reflec- tions, even though they are arguably the most destructive. (The minimization of these reflections is one of the strongest arguments for the tall, line source loud- speakers that Wisdom Audio builds.) This leaves you with eight “first reflections” that you should consider minimizing somehow. These points are easily found by having a friend move a small mirror along the four walls of the room, while you sit at the listening position. Any place on the wall where you can see a reflec-
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