QRD Diffuser

(6 customer reviews)

121 194  +tax

Our customers with an EU tax number can buy tax-free!

In case of a bank transfer, we give a 7% discount up to EUR 1000 on the total price of the purchase!

SKU: 8543366876 Category:
MPN: 8543366876
Brand: Perfect Acoustic


Additional discounts in case of bank transfer:

up to 1000 EUR: 7% discount

1001-1499 EUR: 9% discount

1500-2499 EUR: 11% discount

2500-4000 EUR: 13% discount 

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7 lamellae

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

We offer a 2-month money back guarantee on all our products!

If you are not satisfied with the purchased product, you can return the product without giving a reason within 60 days of receiving it.


The properties of QRD diffuser:

Diffuser are made of laminated blockboard or genuine pinewood.
With their design we tried to achieve that it diffuses the sounds in the largest bandwidth while absorbing the bass.
For those places where the average sound is not enough!


acoustic diffusers color

  • natur, real wood (pine) 104x64x10cm, 120x64x10cm size
  • dark, laminated board 104x64x10cm size
  • light, laminated board 104x64x10cm size
  • white, laminated board 104x64x10cm size
  • black, laminated board 104x64x10cm size

Foldable wooden legs are also available on request


Science behind diffuser

The diffuser is a first-order device designed to diffuse the directed sound waves and to decrease the primary reflections, the standing waves and the rattling echo. It is an excellent complementary device of a sound absorption panel , as it does not drain the sound energy like an acoustic panel does.

The QRD  reflects the energy into the room. But contrary to the flat and straight reflective surfaces, which reflect energy, the  diffusers diffuses the sound to various directions and in different time thanks to the wells of varying depths. That eliminates the direct mirror point reflection and gives the impression that it is in a wider and larger environment.

Although people have used the diffusion of sounds since the Roman times the modern mathematics created new designs in the past years, which have measurable results possible to calculate. The physician M Schroeder – the moving spirit of first-order diffusers – created series of mathematically calculated wells of varying depths. These were set to diffuse equal volume of energy based on pre-calculated dimensions.


The sound arrives as wave front and enters the phase grid of the diffuser where it will be reflected to the room. As the depth of the wells varies the energy exits in different times relatively. This moves the relative phase or the time difference (time shift) and spreads the energy among the wells creating thereby a spatial diffusion.


The sound arrives as a wave front (blue). Without diffusion the flat and hard surface of the wall reflects the energy (red) like a mirror which causes echo. These can be even the first-order reflections, which we hear in the form of rattling echo.

sound reflection with diffuser

The wave front enters – the energy strikes first into the shallow wells and is reflected into the room while the remaining part flows into the deeper wells. The ‘time shift’ happens with the passing of time when it enters in, reflects and exits the diffuser.

sound reflection with

When identical frequencies enter in and exit the same wells simultaneously, they are in phase and strengthen each other. If they exit at different times the dip of phase will happen in relation to the frequency and to the depth of the well.

sound reflection with

Once the sound waves exit the different wells they interact and the energy will be diffused through the phase grid which causes horizontal “spatial shift”. This dissipates the sound in the room resulting greater sense of space.

Setting of low frequency performance

The sound consists of various air molecule compressions which are called sound waves and their length varies depending on the frequency. Lower frequencies have longer wavelength than the high ones.

They contain more energy at the same amplitude than the shorter high frequency sound wavelengths which make the control even more difficult. In addition, it is generally accepted that the sound begins to become directional above the range of 300Hz.

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 objective for the  diffusers.


When planning the first-order  diffusers the deepest well, the density of the material and the specific gravity determine the lowest frequency that it is able to diffuse. It is also important that the diffuser should be structurally rigid and heavy enough in order to avoid that the bass causes unexpected resonance and it should be of high weight enough for the energy not just passing through the wells.

This is rather related to the sound diffusing effect of the diffuser which does not stop at a given frequency but has decreasing effect as the frequency decreases. That means that the  diffusers will operate smoothly from 150Hz. As most people agree that it is able to handle the sound even below that frequency range (actually, not to the extent as from 150Hz) it is advisable to take into account also the lower frequencies.

High frequency sounds

Clap your hands for fun in an empty room and you will probably hear a series of echoes as they are bouncing on the wall, the ceiling and the floor and are reflected from there. We call that rattling echo which is very powerful in rectangular rooms with hard surfaces.

What you hear is the high frequency sound waves bouncing off these surfaces. The high frequencies are rather directional compared to the low frequencies that is why they act as a bouncing ball. Compared to the bass they quickly lose their energy at the same amplitude when they pass through any agent such as air, fluid or solids.

How can I use the QDR diffuser?

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

The QDR series is optimised 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.


The diffuser must be heavy and rigid in order to function well 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 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 in ear level at sitting position so that the centre of the diffuser should be in the level of your ear. Of course, you do not have to mount these diffusers as they stand stable on the ground and fully do their job.

Sound diffuser Positioning

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

Flexi Acoustic Diffuser the wall

Wide wall spaces

In rooms where the wall behind the listening position is very wide you can decrease costs by adding a broadband acoustic panel and meanwhile it handles the bass. This is particularly important in order to improve the acoustics and achieve a smooth sound in the listening position.

If you want the same size as the diffuser you can order a custom sized acoustic panel as well. Custom size production does not increase the price. Its alignment will be simple and attractive thereby. The best solution is that you put the  diffusers into each other as this results a balanced diffusion.

diffuser placed in a wall

Flush mounting in the wall

Do you build a control room, home theatre 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.

diffusers placed in a wall

The audiophiles are probably the most demanding listeners. By adding QDR diffusers the disturbing reflections may be eliminated in such listening spaces while it maintains and may also increase the sense of space and air. This is particularly important when listening to jazz or classical music that have been recorded in an acoustically spacious area as the advantage of these recordings is the natural acoustic environment.

QDR diffuser FAQ

Do all diffusers function the same way?

No. The way the diffusers operate is that they reflect and diffuse the sound energy in the room. The massive diffusers of high density are capable to control the low frequencies while the thin and light diffusers can control only the higher frequencies. The size, weight and design of the diffuser plays a very important role in its operation.

Why do certain companies state that the plastic or styrofoam or foam diffusers will be effective also at lower frequencies?

Because of the income, of course. Not the effect and the regular customer is important for them but that they deceive the customer once or twice. As these are generally cheaper (not always) everyone starts with them and only after they recognise that these are ineffective, our premium quality products come up. Actually, their purse will be considerably smaller by then.

Why are the diffuser so expensive?

The problem with the real QDR diffusers is that there is no simple way for the production, it is not like a simple bookshelf. The QDR diffusers are mainly handmade, hand glued, hand assembled and hand packed which requires a lot of time. This is why it is so expensive.

Can I prepare my own  diffuser?

Yes, of course. But it is not sure that it will be efficient. If it is wrongly calculated and measured it will rather do wrong than benefit.

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

In particular in the primary reflection points, behind the loudspeakers on the right or on the left mirror point or behind the listening position.

Can I repaint the diffuser?

Yes, of course but we sell it in 5 different colours beside natural colour that you can check in the photos.

acoustic diffusers color

How do you deliver the diffusers?

I deliver it assembled in 6-layer packaging, ready to use.

In which area this diffusers betters other products?

We tried to create such an acoustic panel by which we can treat the entire bandwidth without damaging the high frequencies
We always put great emphasis on the use of materials.
Styrofoam, xps, foam etc. are not suitable for scattering the sound in the entire frequency range.


Our diffusers are made of real wood, due to the natural properties and structure of the wood material (knots, lumps, staining due to leaking resin), the pickling / painting will not be even, the shades may be different on the entire surface of the diffuser, therefore we cannot complain to accept.
(The beauty and style of natural wood lies in the fact that due to the veining and the structure, special colors and shades can be achieved during painting / pickling.)

Additional information

Weight 17 kg

black, dark oak, light oak, natural, white


104x60x10cm, 120x60x10cm, 60x60x10cm

6 reviews for QRD Diffuser

  1. Kazi

    You make a very good sound.Nice workmanship.I can only recommend!

  2. Gábriel

    Many have recommended these panels.
    I thought after that many reviews I wouldn’t shoot next.
    And they were right.
    Like service as the quality of the product is excellent!
    Go to the 5 stars!

  3. Kazi

    There is only such qrd diffuser in my studio.I can only recommend!

  4. Endri

    Since I bought 4pc QRD diffusers, I love working on oth.Go to 5 stars.

  5. Thanasis Tsiroukis

    My new real wood qrd diffuser just arrived today. I already own 2 qrd’s of the previews model, and i must say that the new one’s are even better!!! Great work perfect acoustic!!!

    • admin

      Thanks! Glad you are satisfied!

  6. Peter D.

    Very good quality. I am maximally satisfied.

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