Custom Audio Designs Ltd 

Acoustic Diffusers | Sound Diffusers | Diffusion Panels | Sound Scattering Panels

QRD 734 2D DiffuserQRD 734 2D DiffuserQRD 734 2D DiffuserQRD 734 2D DiffuserQRD 734 2D Diffuser

  • Quadratic Residue sound diffusion.
  • Recording Studios.
  • Post Production Studios.
  • Practice Rooms.
  • Home Theatres.
  • Mastering Studios.
  • Wood finish, paintable finish.
  • Can be surface or flush mounted.
  • Can be oriented to provide two dimensional diffusion in the far field.
  • Attractive finish.

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RPG QRD 734 acoustic diffuser


  • It's wide bandwidth, low cost, and broad selection of finishes make it a logical choice for music education facilities, recording studios, worship spaces, auditoriums, theaters, and performing arts facilites.
  • This one dimensional diffusor is a modular, computer designed phase grating which produces a directional hemidisc polar response that can be oriented in any direction.
  • It also provides low frequency absorption below the design bandwidth due to the RPG pressure gradient mechanism.

Problem and Solution


Interfering reflections that degrade speech intelligibility, gain before feedback, and music quality can be controlled by absorption and diffusion. Since commercial surfaces that provided uniform diffusion over a wide frequency range and for all angles of incidence were not available, absorption was used solely to control reflections. This treatment created “dead” spaces.


The QRD 734 is a quadratic residue acoustic diffusor based on mathematical number theory. Now a predictable diffusive surface treatment is readily available.


RPG QRD 734 Diffusion Graph 


Compared to a flat reflector panel, the QRD 734 offers significant diffusion above the diffraction limit of 565Hz, which is equal to the speed of sound (1130ft/sec) divided by the 2' dimension of the panel. As the frequency increases above 565Hz, the graph indicates how the reference reflector becomes more and more specular, whereas the QRD 734 provides a uniform diffusivity.

QRD 734 Absorption Graph
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The wooden QRD® 734 contributes minimal absorption.


The QRD 734 is typically mounted on a cleat and secured. For installations that require a flush mount the units should be framed out much like an opening for a window.


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All information contained in these details is given in good faith but without warranty.
Custom Audio Designs reserves the right to alter the specifications of any product without notice.
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