The Story Behind HOFA-AkustikJochen Sachse
I founded our room acoustics division, HOFA-Akustik, in 2007. In this article, I want to tell you the story of how we became a manufacturer of diffusers, absorbers, frames, bass traps, acoustic curtains, dividers and wall & ceiling sails to optimize the acoustics of your studio, office or living space.
The role of a salt mine for HOFA-Akustik
A visit to a large underground hall in the salt mine of Bad Friedrichshall in Southern Germany gave me the idea of making acoustic modules. The hall, which lies almost 200 metres below ground level, was blasted and chiselled into the mountain with no musical intentions at all. The sheer size of the structure, with its hard, parallel stone walls, and the apparent lack of acoustic measures were in stark contrast to the perceived acoustics – all my clapping, snapping, shouting and whistling triggered an extremely well-balanced, fascinating reverberation, which I would never have expected in such a place.
The reason for this pleasant sound was soon identified: the walls were far from being plain! Everywhere, there were edges and chisel marks with a depth of roughly 10 cm, which reflected the sound diffusely and also absorbed it a little due to the open-pored fine structure. It made a lasting impression on me that a huge room could sound so attractive and balanced, even though no one had even thought about acoustics during its creation, let alone an acoustician – the decisive factor was clearly the rough surface of the walls.
At that time, we were building several new control and recording rooms in the HOFA-Studios, and I was also designing a small control room at home. So I immediately started thinking about how this rather chaotic diffusion of the salt mine could be transferred to studio facilities.
Our first acoustic module: the HOFA Diffusor
Of course, I started with an extensive search for acoustic modules that were already on the market. However, the results were very disappointing, and I realized that there were probably a lot of rooms in the world waiting for effective and affordable acoustic modules. Moreover, the students at our online academy for audio engineering, which was founded in 2005, often contacted us about the acoustic inadequacies they had to deal with in their projects.
So it was time to think about attractive acoustic solutions that would meet professional requirements at a reasonable price and could be quickly and easily installed anywhere, but also removed again if necessary.
The Diffusor was developed quite quickly. I based the structural depth of 11 cm on the chisel and stoping marks in the mine. The open-pored fine structure of untreated wood, similar to rock in the mine, provides that little bit of absorption. In fact, I also tried prototypes made of plastic and other materials at the time, but nothing sounded as good as wood.
Production in the "Lebenshilfe"
Thanks to my social year at the Lebenshilfe Bruchsal, I was familiar with the possibilities of the carpenter’s shop at these workshops for people with disabilities. This allowed me to make sure that our Diffusor (as well as all the other acoustic modules) could be built at the Lebenshilfe without any problems. Woodwork in particular is popular among people with disabilities, and we are proud to be the largest client for woodwork at the workshops in Bruchsal. Also based on the close cooperation with the Lebenshilfe is the successful inclusion of disabled employees at HOFA.
In studios, spaciousness is often added to instruments and voices at the mix stage, so a wall and ceiling absorber was the obvious next module to develop. We tested a wide variety of porous absorbers, and the chosen material was the one that could “swallow” the frequencies most evenly.
I racked my brains for a long time about how to attach the modules to the wall and ceiling. The idea of working with special wooden frames solved several problems. Mounting the modules on the ceiling is easy, and the modules can be quickly exchanged for sound adjustments. Since the extremely practical frame for exchangeable acoustic modules did not yet exist, we had it patented.
When calibrating the control rooms, I was always bothered by the irregularities in the low frequency range. Moving the loudspeakers and the subwoofer never produced an acceptably balanced result.
Months of tests with different shapes and materials finally brought the solution in 2009 with the Basstrap, which is still being built at the Lebenshilfe today.
With Diffusor, Absorber, Frame and Basstrap, we finally had everything we needed to optimize any room for professional music productions.
HOFA Acoustic Curtains
When speaking with our customers, we were more and more confronted with problem areas such as sound insulation, acoustic separation and also large-scale absorption in rehearsal rooms, offices and halls. As a result, we started working with acoustic curtains in 2011.
As always, we first looked at the options on the market and initially planned to cooperate with other manufacturers. However, since we had received many requests for individual sizes and configurations right from the start, we decided to conduct intensive material tests in the HOFA-Studios and to develop our own curtain concept for spatial separation and absorption based on these results. Setting up the company’s own sewing shop in Karlsdorf at the beginning of 2015 was the obvious next step.
We received more and more requests for large and small offices, living quarters and halls of all kinds. In addition to the acoustic effect, a discreet design and an unobtrusive appearance played a decisive role in these premises. To meet these requirements, we tested and developed new materials. The result is the highly effective and at the same time sustainable, climate-neutral HOFA PureAkust. Our first wall and ceiling sails were introduced in 2018, and the PureAkust series was completed with mobile walls which are often used as room dividers.
Planning & measurement
The very fact that we always have competent acousticians and audio engineers in our recording studios and at the HOFA-College made it a logical step to also offer professional advice and room planning. In the beginning, we planned the ideal positioning of acoustic modules on the phone and with simple sketches. Today, dodecahedrons and measuring microphones are used where necessary, and we work with special software to create the perfect room plan, which is then displayed in 3D.
Environmental awareness at HOFA-Akustik
Environmental protection and sustainability are key factors in the way we will experience our future. With decisions for a paperless office (2005), over 1,000 sqm of solar panels, power-heat cogeneration (2007), electric mobility (2017) and CO2 neutrality, it is important to me and my staff to make a contribution with HOFA. Short transport routes with suppliers from the neighbourhood have proven their worth over decades.
Especially in our acoustics department, we are constantly looking for more environmentally friendly materials with outstanding efficiency, and we have always been prepared to break new ground for better acoustics.