Home Theater Sound Design: Making the Grade with Diffusion Gradings

No matter how dedicated a home theater owner may be to great sound production, a good diffuser is not the most economical sound treatment currently on the market. Most of the products available are based on number theories that promise to generate reflections that are phase coherent and steered all around the room based on series of wells and slots of varying depths in specially designed boxes. Rather than running the numbers, there are some simpler steps to improving home theater sound.
• Get bent. Many sound experts do not put a great deal of stock into complicated systems of grade diffusers that require extensive mathematical intervention. The central problems with most high-end diffusers are:
o Frequency inconsistence. In relation to acoustic wavelengths, only series of frequency bands are properly diffused.
o Frequency incoherence. Frequencies in between bands are returned as frequency incoherent.
o Frequency bounce. Unbent frequencies result in a chaotic bounce off the wall.

• Back to the future. To address not only the cost of new-on-the-market diffusers but also the often unreliable performance, many home theater experts recommend poly-cylindrical built-in panels. Although dating back before diffraction gradings became popular, the poly panels function well by putting the beams under compressive force and producing the same result as is found from the bending of panels.

• Buckle up. For those home theater owners who have the ingenuity and initiative, an alternative to commercial diffusion is a self-made panel. These steps will produce the desired results without the added expense:
o Materials. Measure and cut a frame for the desired space. Insert a slightly oversized piece of plywood in the frame
o Function. The bending of the plywood makes a smooth curve out of the constructed panel, allowing for a buckled beam.
o Location. For those designing and building a home theater with a larger back wall, it is possible to put the panels into the walls for a special touch.

The diffraction grading style diffusers available on the market can be expensive. However, there are some companies making corrugated surface grading types out of molded plastic. The only downside to the molded plastic versions is the possibility of rattling due to their light weight, but they are considerably more affordable. Quite possibly the best route is to construct a frame and bend the corresponding panel rather than purchasing a commercial product.