The
QRD® Diffusor has long been
the industry standard for recording studios. The new
QRD PA is a lower-cost version of the classic.
This
one-dimensional diffusor is a modular, reflection phase
grating, which produces a directional hemi-disc 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.
Its
wide bandwidth and low cost make it a logical choice
for any project studio or home theater.
Problem
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.
Solution
In 1983, RPG® introduced the first commercial QRD®
Diffusor, based on mathematical number theory. Now the
QRD® PA offers a lower cost alternative for the
Pro Audio and Project Studio environment.
Diffusion
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® PA provides a uniform diffusivity.
Installation
The QRD® PA is mounted on a supplied cleat and secured.
For installations that require a flush mount the units
are framed out much like an opening for a window.
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Northampton, MA 01062 
