The QRD has become a classic shape in architectural acoustics, from its birth in 1987 it can now be found in churches, schools, theaters and studios all over the world. The Formedffusor is a molded unit based on the QRD and designed to lay into a standard 15/16″ T-Bar ceiling grid. The surface of the Formedffusor is designed to provide a more uniform sound field through mid and high frequency diffusion while the thin wall construction adds some low frequency absorption via membrane resonance at the face.


The Harmonix-K is readily available in a standard white, slightly textured, satin finish. Please see the TPS Color Palette under the Technical Data tab below for color options.


The Formedffusor is designed to drop into a standard T-Bar grid. It can also be flush mounted to a wall or ceiling with appropriate blocking. See details below under the Drawings tab.

Formedffusor is a Trademark of RPG Acoustical Systems LLC



Formedffusor thmb

Since its introduction in 1984, the number theoretic QRD 734 Diffusor has proven to be a versatile general purpose diffusor. The uniform scattering, wide bandwidth, and broad selection of finishes make the QRD a logical choice for almost any speech, critical listening, or performance facility. The Formedffusor brings this proven technology to a wider audience because of its low price, ease of installation, Class A fire rating, light weight, impact resistance, and color and texture options.






Wooden QRD diffusors may be too heavy for some ceiling applications or too expensive for large scale coverage. There is a need for a lightweight, Class A, cost effective, molded plastic QRD.


To address this problem, RPG developed a lightweight, thermoformed panel made of Class A Kydex. The diffusor has a graceful curved inner and outer radii for an attractive appearance. Kydex is stiff and impact resistant, allowing the Formedffusor to be use in almost any wall or ceiling configuration.


  • QRD number theory sound diffusion.
  • Lightweight thermoformed fabrication
  • Low frequency diaphragmatic absorption
  • Custom colors.
  • Can be oriented to provide one or two dimensional diffusion in the far field


Please direct all sample inquiries to