Quadratic Residue Diffusor
A The Quadratic Residue Diffusor shall be the model QRD® 734 4' x 2' as manufactured by RPG® Diffusor Systems, Inc., Upper Marlboro, MD 20774. Tel: 301-249-0044, Fax: 301-249-3912.
B The Quadratic Residue Diffusor shall be fabricated with a 1/2" Class A Duraflake core and veneered with a rotary cut uniform white birch.
C The Quadratic Residue Diffusor shall work on the one dimensional reflection phase grating principle, using an array of wells of equal width separated by thin dividers. The depths of the wells shall be based on the prime seven quadratic residue theory sequence.
D Sound diffusion in the horizontal plane shall be provided by wells in the vertical position while diffusion in the vertical plane shall be provided by wells in the horizontal position. The Quadratic Residue 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 Type A mounting shall be as follows:
| 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | NRC |
| 0.23 | 0.24 | 0.35 | 0.23 | 0.20 | 0.20 | 0.25 |
F Diffusion Coefficients for the product shall be measured in accordance with AES-4id-2001. The normal incidence diffusion coefficients are listed below at octave-band centers. The mean and standard deviation (
)
of the 1/3-octave-band coefficients are also tabulated. | 125Hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | MEAN | SD |
| 0.71 | 0.73 | 0.88 | 0.80 | 0.69 | 0.56 | 0.72 | 0.08 |
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 Quadratic Residue Diffusor shall have a composite Flame Spread Rating of less than 25 and a Smoke Development of less than 450.
H The Quadratic Residue Diffusor shall be supplied with a clear lacquer finish.
I The overall dimensions shall be 47-1/4"(H) x 23-5/8"(W) x 9-1/8"(D) and weigh no more than 58 pounds.
Wood 4' x 2' CSI Specifications
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2000, RPG Diffusor Systems, Inc. |