QRD Diffuser

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7 lamellae

1. Size: 120x60x10cm         Weight  17kg
2. Size: 104x60x10cm         Weight  14kg

The Properties of QRD Diffusers

The diffusers are made from laminated blockboard or genuine pinewood.
With their design, we aimed to achieve optimal sound diffusion across a wide frequency range while also absorbing bass.
For areas where average sound absorption is insufficient, we offer the following colors:

 

• Natural, real wood (pine) – 104x64x10 cm, 120x64x10 cm

• Dark, laminated board – 104x64x10 cm

• Light, laminated board – 104x64x10 cm

• White, laminated board – 104x64x10 cm

• Black, laminated board – 104x64x10 cm

 

Foldable wooden legs are also available upon request.

 

Science behind diffusers

The diffuser is a first-order device designed to diffuse the directed, sound waves and decrease the primary reflections, the standing waves, and the rattling echo. It is excellent complementary advice for a sound absorption panel, as it’s not draining the sound energizer acoustic panel does.

The QRD diffuser reflects energy into the room. However, unlike flat and straight reflective surfaces, which simply reflect energy, these diffusers scatter the sound in various directions and at different times, thanks to the wells of varying depths. This eliminates direct mirror point reflections and creates the impression of being in a wider and larger environment.

Although people have used diffusers since Roman times, modern mathematics has led to new designs in recent years, offering measurable and calculable results. The physicist M. Schroeder, a key figure in the development of first-order diffusers, created a series of mathematically calculated wells with varying depths. These were designed to diffuse an equal volume of the wavefront across pre-calculated dimensions.

Theory

The sound enters and passes through the phase grid of the diffuser, where it is reflected as energy. As the depth of the wells varies, the energy exits at different times relative to one another. This causes a shift in the relative phase or wavefront difference (time shift), spreading the energy across the wells and thereby creating spatial diffusion.

The sound arrives as a wavefront (blue). Without diffusion, the flat and hard surface of the wall reflects the energy wavefront like a mirror, causing an echo. These can even be the first-order echoes, which we perceive as a rattling echo.

The wavefront enters, and the energy first strikes the shallow wells, reflecting into the room, while the remaining part remains unchanged. A time shift occurs as the sound enters the deeper wells, and over time, the real frequencies are diffused through the diffuser.

When identical frequencies enter and exit the same wells simultaneously, they are in phase and strengthen each other. This happens at specific times based on the frequency and the depth of the well, creating a dip phase effect.

Once the sound waves exit the different wells, they interact, and the energy is diffused. The setting of the low-frequency waves causes a horizontal “spatial shift,” dissipating the sound in the room and resulting in a greater sense of space.

 

The Setting Low-Frequency Performance

Sound consists of various air molecule compressions, which are wavelengths that vary depending on the frequency. Lower frequencies have longer wavelengths than higher ones.

This means lower frequencies carry more energy at the same amplitude compared to the shorter high-frequency wavelengths, making control more challenging. Additionally, it is generally accepted that the sound begins to lose its low-frequency tone above the range of 300 Hz.

If a diffuser’s primary function is to break up directional sound energy, then the optimal diffuser must reach down into this lower frequency range. These criteria determine the low-frequency performance objectives for users.

What about planning?

When planning first-order diffusers, the density of the material and its specific gravity determine the lowest frequency it can effectively diffuse. It is important that the diffuser be structurally rigid and heavy enough to prevent unwanted resonance, while also being dense enough to prevent bass frequencies from simply passing through the wells.

This is related to the sound-diffusing effect of the diffuser, which does not stop at a specific frequency but gradually decreases as the frequency lowers, allowing the sound to operate smoothly from 150 Hz. While most people agree that the diffuser can handle sound below this frequency range, it is advisable to consider even lower frequencies in the design.

High Frequencies

Clap your hands for fun in an empty room, and you will probably hear a series of echoes bouncing off the walls, ceiling, and floor. These are high-frequency reflections, which are very prominent in rectangular rooms with hard surfaces.

What you hear are high-frequency waves bouncing back from these surfaces. High frequencies are more directional compared to low frequencies, which is why they behave like a bouncing ball. Unlike bass, they quickly lose energy at the same amplitude when they pass through any medium such as air or solids.

How can I use the QDR diffuser?

The diffuser is a high-performance diffuser designed for professional studios and more sophisticated home theatres and hi-fi rooms.

The QDR series is optimized so that it would be possible to mount several diffusers side by side. That enables the client to set the desired number of diffusers in a place that covers the desired wall. After installing them to their position the problems such as modal distortion, rattling echo and standing waves decrease significantly.

Composition:

The diffuser must be heavy and rigid to function well and also in a lower frequency. Of course, that leads to questions such as positioning or mounting. The good news is that we designed the QDR diffuser so that it can be easily and quickly mounted. You have to mount it with the same technique as in the case of a series of kitchen cabinets.

If you mount it on the wall you have to put it later level at a sitting position so that the center of the diffuser should be at the level of your ear. Of course, you do not have to mount these diffusers as they stay stable on the ground and fully do their center

Sound diffuser positioning

The optimal position in a room is usually behind the listening position or behind the loudspeakers on the right or the left side. Of course, a wider room will provide a wider diffuse area. In rooms with larger workspace, it is advisable to combine it with membranes or broadband acoustic panels to save money.

Wide Wall Spaces

In rooms where the wall behind the listening position is very wide, you can reduce costs by adding a broadband acoustic panel to handle the bass. This is particularly important for improving acoustics and achieving a smooth sound at the listening position.

If you prefer the same effect with a diffuser, you can also order a custom-sized panel. Custom-size production does not increase the price. Its alignment will be simple and attractive, resulting in balanced diffusion.

Flush mounting on the wall

Do you build a control room, home theater,tre, or, studio? You can mount the QRD diffuser just as easily as a shelf. The flush mounting does not affect the diffusion performance but it can improve the aesthetics of the room design if you are willing to do the framing. If the studio is already finished you can build a false wall for the mounting of the diffusers. It can be a great opportunity to provide acoustic isolation between the rooms or to install a big built-in bass trap.

Audiophiles are probably the most demanding listeners. By adding QRD diffusers, disturbing reflections can be eliminated in such listening spaces, while maintaining or even enhancing the sense of space and air. This is especially important when listening to jazz or classical music recorded in an acoustically spacious environment, as the advantage of these recordings lies in the natural acoustic ambiance.

QRD Diffuser FAQ

Do all diffusers function the same way?

No. Diffusers operate by reflecting and diffusing sound energy within the room. High-density, massive diffusers are capable of controlling low frequencies, while thin and light diffusers are only effective at controlling higher frequencies. The size, weight, and design of diffusers play a crucial role in their performance.

Why do certain companies state that plastic, styrofoam, or foam diffusers will be effective?

Because of profit, of course. The effect is not their primary concern; returning customers are. Since these materials are generally cheaper (though not always), everyone starts with them. Only after customers recognize their ineffectiveness do they turn to premium-quality products. By that time, their budget is usually much smaller.

Why is the diffuser so expensive?

The problem with real QRD diffusers is that they are not simple to produce, unlike a basic bookshelf. QRD diffusers are mainly handmade: glued, assembled, and packed by hand, which requires a lot of time. This is why they are more expensive.

Can I prepare my own diffuser?

Yes, of course. However, there’s no guarantee that it will be effective. If it is incorrectly calculated and measured, it will likely do more harm than good.

Where is the best place in the room to position the diffuser?

The diffuser should be placed primarily at the reflection points, behind the speakers on the right or left mirror points, or behind the listening position.

Can I repaint the diffuser?

Yes, of course. However, we sell the diffusers in 5 different natural colors, which you can check in the photos.

How do you deliver the diffusers?

We deliver them fully assembled in 6-layer packaging, ready to use.

Are there any other colors besides the ones listed above?

We have designed an acoustic panel that treats the entire frequency range without compromising the high frequencies. We always place great emphasis on the materials used.

Styrofoam, XPS, foXPS, etc., are not suitable for scattering sound across the entire frequency range.

 

Our diffusers are made of real wood. Due to the natural properties of the wood (such as knots, lumps, and staining from leaking resin), the staining/painting may not be even, and the shades may vary across the surface of the diffuser. Therefore, we cannot accept complaints regarding these variations.

(The beauty and style of natural wood lie in its veining and structure, which allow special colors and shades to be achieved during painting or staining.)