Well balanced acoustical designs contain an appropriate combination of absorption, reflection, and diffusion. In many applications, however, limited budget or surface treatment thickness preclude the use of diffusion. Absorptive, fabric wrapped panels are specified for lack of an alternative. Unfortunately, wide area application may lead to an acoustically "dead" environment without "air" or ambiance.

To solve this problem, RPG® developed and patented the Binary Amplitude Diffsorbor™: the first flat, zero depth diffusing absorber. A BAD™ Panel simultaneously provides uniform sound diffusion at high and mid band frequencies and crosses over to pure absorption below the diffusive cutoff. The energy that is not diffused is absorbed. For a competitive evaluation of commercial products that claim to provide equivalent performance to the Bad Panel, we invite you to examine our White Paper.

It's Digital!
To accomplish diffsorption, RPG® developed a new planar 2 dimensional binary reflection amplitude grating consisting of a 31 x 33 element array of 1,023 0.5 sq. in. absorptive or reflective areas. BAD Panel gridThe reflective areas (black in illustration to left) map to the "1" bit and the absorptive areas (white) map to 0, or vice versa. The distribution of these resorptive binary elements is based on a 2 dimensional optimal binary sequence with a flat power spectrum. The resulting variable impedance surface forms a binary reflection amplitude grating suggested by James Angus. This is in contrast to RPG®'s reflection phase gratings which use phase variation, rather than amplitude variation, to provide diffusion. The Binary Amplitude Diffsorbor™ (BAD™) Panel provides diffusion about an octave above the frequency whose wavelength is twice the size of the binary element. This explains the limitation of traditional variable impedance arrays. For example, 1' x 1' panels provide diffusion up to about 1 kHz. Remaining high frequency reflections would still corrupt speech and music quality.

Bad Panel AssemblyThe BAD™ Panel consists of a binary mask attached to the face of a semi rigid fiberglass panel. The panel is upholstered in a decorative fabric to completely conceal the acoustical functionality. The BAD™ Panel extends the acoustical performance of traditional absorptive fabric wrapped panels and allows wide area coverage without excessive deadening. Acousticians now have a diffsorptive alternative to traditional purely absorptive fabric wrapped panels at competitive prices. The BAD™ Panel is ideal for any facility that needs reflection control from a decorative, upholstered, thin, and cost effective wall or ceiling panel.

Problem
Traditional foam and fabric wrapped absorptive panels offer a cost effective, low profile approach to providing reflection and reverberation control. However, these panels offer little sound diffusion and large area application may lead to an acoustically "dead" space. Variable impedance arrays offer some help, but cannot provide diffusion at mid and high frequencies.

Solution
RPG® developed an innovative variable impedance panel by fabric wrapping an optimal binary template consisting of reflective areas and holes over a semi rigid fiberglass panel. The resulting Binary Amplitude Diffsorbor™ Panel provides mid and high frequency diffusion and low frequency absorption.

Absorption
The BAD™ Panel offers an increase in bass absorption over a standard upholstered 1" panel below 1000 Hz, and a decreased absorption above this frequency for a 5/8" diameter and the standard 1/2" diameter hole. The binary template allows the sound above 1000 Hz, which was conventionally lost to absorption, to be uniformly diffused providing reflection control without destroying the room's ambiance.

Angular scattering response
Angular scattering responseFor normally incident sound, the graph illustrates the angular response at 12.5 kHz. The flat reflector scatters sound primarily into the 90° specular direction. The wall mounted absorptive panel has similar response, only attenuated. The BAD™ Panel decreases specular scattering and more closely approaches the uniform ideal diffusion line.

Installation
For fixed wall mounting, simply secure the ImpaleIt™ clip to a surface, with screws or with a hook and loop fastener. Make a mark at the desired height of the panel and 1" above that for alignment. Line up the panel with the higher mark and gently pierce the back of the panel with the triangular prongs. Then press firmly into the ImpaleIt™ clip and press downward until the panel settles against the wall at the desired height. For removable wall mounting, simply attach a "Z" channel to the surface and hang the ImpaleIt™ clip on the channel. Make a mark at the desired height and 1" above that for alignment. Align the panel at the mark 1" above the desired height and gently pierce the back of the panel with the triangular prongs. Then firmly press the panel into the ImpaleIt™ clip, allowing it to pierce the rear of the panel and push downward until the panel settles against the wall at the desired height.

Further comple information and specifications can be found on RPG's BAD™ Panel page.