Pyramidal Diffusor
A The Pyramidal Diffusor shall be the Golden Pyramid™ as manufactured by RPG Diffusor Systems, Inc., Upper Marlboro, MD 20774. Tel: 301-249-0044, Fax: 301-249-3912.
B The Pyramidal Diffusor shall be fabricated from Fiberglass Reinforced Gypsum.
C The Pyramidal Diffusor shall be pyramidal in shape and symmetric along one axis and asymmetric along the other axis conforming to proportions as defined by the Golden Mean.
D The Pyramidal Diffusor shall be free from excessive resonance and provide diffusion in the far field based on the specular reflection principle. The diffusor may be rotated to achieve a variety of patterns that will provide a highly effective scattering surface.
E Absorption Coefficients and Noise Reduction Coefficient for the product shall be measured by an independent, accredited NVLAP facility according to the test methods as defined by ASTM C 423 and ASTM E 795. Random incidence Absorption Coefficients for the product in an E-400 mounting shall be as follows:
| 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | NRC |
| 0.39 | 0.19 | 0.10 | 0.10 | 0.08 | 0.14 | 0.10 |
F Diffusion Coefficients for the product shall be measured in accordance with the recommendations of the Audio Engineering Society Working Group SC-04-02 boundary measurement technique. The directional diffusion coefficient is given by the standard deviation of the 1/3-octave polar response, for a given angle of incidence, and normalized by the response of a flat panel of similar size. The average incidence diffusion coefficients determined at 5° intervals between ± 85° are listed below at octave-band centers for the three unique orientations. The mean and standard deviation (SD) of the 1/3-octave-band coefficients are also tabulated.
| 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | MEAN | SD |
| 0.75 | 0.81 | 0.79 | 0.73 | 0.51 | 0.24 | 0.67 | 0.21 |
| 0.77 | 0.80 | 0.72 | 0.78 | 0.60 | 0.35 | 0.69 | 0.16 |
| 0.76 | 0.82 | 0.77 | 0.80 | 0.61 | 0.32 | 0.69 | 0.19 |
G Flame Spread and Smoke Developed shall be tested by an independent, accredited NVLAP facility according to the test methods as defined by ASTM E 84 and NFPA 255. The Pyramidal Diffusor shall have a composite Flame Spread Rating of less than 25 and a Smoke Development of less than 450.
H The Pyramidal Diffusor shall be supplied in a painted, ceiling white finish.
I The overall dimensions shall be 23-3/4"(H) x 23-3/4"(W) x 8-1/4"(D) and weigh no more than 6 pounds.
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2000, RPG Diffusor Systems, Inc. |