Why Diffusors Are Essential for Your Room AcousticsJan Bönisch
Diffusors can be used effectively to optimise the acoustics of your room. Combined with absorbers, acoustic curtains, bass traps and acoustic sails, they make for good room acoustics and help to ensure that you can record, edit, and listen to music in your room at the highest level. But how does a diffusor work? And how do you use them correctly?
What does “diffusion” mean?“
Diffusion is a form of reflection. Reflection means: Sound waves reach an object and are then reflected at the same angle at which they enter.
(Angle of incidence = angle of reflection)
However, if sound waves hit a diffusor, they are reflected differently depending on their frequency. This creates a well-sounding reflection chaos called diffusion or diffusivity.
What do you need diffusors for?
Diffusors eliminate unwanted flutter echoes and reflections and thus contribute to better room acoustics. In addition, the use of diffusors creates a special, characteristic room sound that can be described as “homogeneous” or “balanced.” The best way to hear the difference is to listen to our room acoustics sound examples – convince yourself of the effect of diffusors:
Diffusors are used for many purposes – they are indispensable for optimising room acoustics in recording and control rooms, home cinemas, hi-fi rooms or in home recording studios.
Why diffusors and not just absorbers?
Absorbers can effectively prevent flutter echoes, too. So why do you need diffusors? Quite simple: absorbers minimise flutter echoes by absorbing the sound. If you try to eliminate all annoying flutter echoes in a room with absorbers, it can quickly happen that the room sounds “dead”, i.e., the reverberation time is too short. Diffusors can be a suitable means of optimising your room acoustics and making the room sound large and lively while avoiding flutter echoes.
What kind of diffusors are there?
A distinction is usually made between 1D and 2D diffusors. One-dimensional diffusors consist of different indentations along one axis. In this way, incident sound is only scattered in one direction. In two-dimensional diffusors, the indentations are arranged along both axes. Therefore, the sound is dispersed in all directions.
HOFA diffusors are 2D diffusors with 36 compartments whose layout is based on a modified QRD design.
What is a QRD diffusor?
QRD is short for Quadratic Residue Diffusors. These are based on a mathematical formula developed by the German physicist Manfred Schroeder – which is why they are also called Schroeder Diffusors. To calculate the depth of the individual compartments of a Schroeder Diffusor, a so-called modulo calculation is made. First, a prime number is determined. Using the formula, the prime number 7, for example, results in 8 compartments, while the prime number 11 would result in 12 compartments. Therefore, Schroeder Diffusors that have 8 compartments are also called 7+1 diffusors.
With 4 HOFA diffusors you can create an 11+1 QR diffusor by creating a point symmetrical pattern. With this layout, the lower cut-off frequency is 700 Hz and the upper cut-off frequency is 2.2 kHz. This results in a symmetrical reflection pattern and the sound is evenly distributed in the room.
For the full effect of the HOFA Diffusors, however, you do not necessarily need a QRD arrangement. Even when combined freely, they can effectively contribute to better and more pleasant room acoustics.
How are HOFA Diffusors manufactured?
HOFA Diffusors are made of birchwood due to its excellent acoustic and optical properties. They are available as a natural variant or in a solvent-free stained version in the colours black, brown, and cream.
We work closely with local workshops for the disabled to manufacture the HOFA acoustic modules. All diffusors are handmade in these workshops with the highest quality standards. In this way, we contribute to the preservation of important social facilities and rely on short transport routes to protect our environment.
How many diffusors do I need in a room?
It is not possible to give a universal answer to this question. An important factor in optimising room acoustics is the use of the room: If you want to record drums in your room, for example, you need a larger number of diffusors to create a lively room sound. In control rooms and home studios, fewer diffusors and more absorbers are used to create a dry, direct room sound so that you can better judge the spatiality in your mixes. In small rooms such as home recording studios (especially with parallel walls), it can be useful to use more diffusors to make the room sound bigger.
You can find more information about the HOFA Diffusors here.