Newsletter

Find Beam Intersection

Set up a flashlight on each speaker so they reflect off the same wall, the right and later the left wall, and converge at the listening position. Use mirror on wall to reflect beams. Where the beams intersect is the image control position. Laying flashlights on the floor provides a “ray tracing” effect as the beams skim the top of the carpet.

Secondary Wall Reflections

So far we have considered mainly “primary reflections” which are those that reflect one time before they get to the listening ear. Here we consider secondary reflections that reflect twice before reaching the listener.

There are 3 side wall beam paths, not just one. Add one sound panel for the early side wall reflection, we hear improvement. But we still have two more sound panels to install, one above and one below the ear level panel. Otherwise, the two reflections cause vertical stage blur and widening. We’ve checked out the near wall primary and secondary reflections.

Next, we take a look at the primary and secondary cross-talk beam paths, the image killing reflections. The primary path is a ear level and as before we have the ceiling and floor secondary bounce paths. Above the primary ear level path is the ceiling-wall bounce and one below it is the wall-floor bounce.

To quiet down the image killing cross-talk sound beams we have to add all 3 sound panels. They will be one above the other, one at ear level, one near the ceiling and the near the floor. With wall to wall carpet there is no floor bounce.

But audiophiles prefer a central Persian carpet between the speakers and listening chair but away from the walls to keep the room’s brighter ambiance. A lower sound panel is needed.

Multiple Wall Reflections

When a speaker is located close to a sidewall we have the expected side wall reflection which slightly widens the sound stage. In effect we have 2 speakers next to each other, the real speaker and the image speaker caused by the wall reflection, and it is located just inside the side wall. In addition we hear lower level multiple time-delayed reflections that occur between the wall and the side of the speaker.