Why do people feel mixed feelings

Feel the music, experience the sound in a new way

Thanks to the particle foam housing, the Zeppy Soundbuddy can swim and even transmit the sound onto and into the water. Image: Zeppy

“She only likes music when it's loud
that's all she hears
she only likes music when it is loud
when it hits her stomach
she only likes music when it is loud
when the ground shakes underfoot
then she forgets that she is deaf ... "

With these lines of text Herbert Grönemeyer celebrated the sound experience for hearing impaired people in his 1983 album “Mixed Feelings”. To experience music, feel the full bass through your body - especially when it is loud. But loud sound and a strong bass are no longer necessary for this experience. A few years ago a music-loving product developer and a plastics expert succeeded in developing a development that significantly changed the sound experience for hearing and non-hearing people.

The start-up founders brought the Zeppy Soundbuddy onto the market. Zeppy is a wireless speaker that is robust, waterproof and makes sounds audible even underwater. A key feature is its housing, which is made of expanded polypropylene (EPP).

An inventor with a passion for music

Rafael Kubisz (left) is founder and managing director of Zeppy Gesellschaft, Prinzersdorf, Austria, and Jürgen Reichl (right) is managing director of Zeppy Gesellschaft, Prinzersdorf, Austria and sales agent of Overath EPP, Oebisfelde, Germany. The team invented the Zeppy Soundbuddy and founded the start-up. Image: Zeppy

Rafael Kubisz is the inventor. With passion and perseverance, he pursued the idea that gave rise to Zeppy. The qualified electrical engineer worked mainly in the product development of promotional items, on behalf of customers and on his own. Kubisz envisioned a loudspeaker that is waterproof, lightweight and robust and, as a portable device, produces an extraordinary sound even in water.

The choice of materials makes the sound system unique

The search for the suitable material turned out to be difficult for the inventor. A chance discovery - a Blackroll at the ISPO trade fair - and, in further research, a cool box made of EPP, on the label of which the manufacturer Overath EPP was printed, provided the material solution for the loudspeaker housing.

Such an EPP thermobox from Overath gave rise to the idea of ​​choosing the suitable Zeppy housing material. Image: Overath

After Kubisz had decided on EPP as the housing material, chance came into play a second time. Jürgen Reichl, who lives in close proximity to Rafal Kubisz, was responsible for the Austrian commercial agency for the cool box manufacturer and plastics processor Overath EPP. Initially, there was a customer-supplier relationship between Reichl and Kubisz. But out of this, the two Austrians founded Zeppy GmbH in 2018. This was made possible by the inventive spirit and the plastics expertise of the two partners. “Rafael Kubisz is an inventor, as he can see in the book, who can think beyond borders,” says Reichl about his partner.

Overath EPP has always been a pioneer when it comes to the development of EPP components, says Reichl. However, mainly in the direction of cooling, folding and thermal boxes. The company has developed its own machines and tools for this purpose. The most famous product is the flip box, which has been on the market for 30 years. Overath EPP has also been producing EPP products at the Oebisfelde site since 2015. "We currently have a little more than 20 systems in use and work with pressure and gap filling," adds Hans-Joachim Hirsch, Managing Director of Overath EPP.


"For me, the EPP offers an ingenious combination of material properties with which I can turn my idea into a specific product."

Raffael Kubisz, founder and managing director of the Zeppy company, Prinzersdorf, Austria.

Design of the loudspeaker housing made of EPP

For Zeppy, the EPP is shaped under pressure in a thermal process that takes place in several cycles. The manufacturing process with conventional tools is rather energy-intensive. First, the EPP raw material is poured into the mold cavity as granules without pressure (crack-gap process), then mechanically compressed and welded and cooled using heated steam. This pressure-filling process in a particle foam system type K68 from Kurtz Ersa takes around 100 s for the Zeppy housing.The tools with a maximum size of 800 x 600 mm are designed in such a way that steam can penetrate and escape through many small openings. The cooling takes place in conventional processes using externally applied water. The special rough surface of the housing is created by the specially designed surface in the tool.

Since the surface of the housing is part of the design, a comparatively high quality standard is placed on the process and the surface quality. “The Zeppy case challenges us in terms of the surface and possible color combinations. Since the user attaches great importance to appearance, feel and sound, we have to be particularly careful during production and ensure that only perfect quality leaves our factory, ”explains Hirsch. Reichl adds: “You have to realize that the surface of EPP components is usually not an essential quality criterion. Components for automotive applications are usually used in areas that are not visible. Every tiny flaw on the surface of the housing of the high-priced Zeppy represents a defect. The housing also has a very small wall thickness of only four to five millimeters. "

"Every tiny flaw on the surface of the Zeppy's housing is a defect."

Jürgen Reichl, managing director of the company Zeppy, Prinzersdorf, Austria and commercial agent of Overath EPP, Oebisfelde, Germany.

In contrast to most components made from EPP, the quality of the surface of the EPP housing is very high. Image: Zeppy, Overath

In order to avoid marks on the surface, the loudspeaker housing is therefore not demolded using an ejector alone. The sophisticated geometry of the EPP component with undercuts on both sides requires a technical trick for demoulding: The component is pushed out of the tool in two directions using an ejector and air pressure. After demolding, the component is tempered at 80 ° C for 4 hours so that the original geometry is restored. “It is thanks to Mr. Reichl, with a lot of personal commitment, that we can produce an extremely small workpiece for the EPP industry, which also shows the limits of what is technically feasible. Zeppy is also a valuable showpiece in this industry, ”notes Kubisz.

Energy-saving tool technology thanks to additive manufacturing with steel

In order to save energy, the tool manufacturer Overath SLM has developed a new tool technology in cooperation with the Aachen University of Applied Sciences and has received Dena's Energy Efficiency Award 2020 for this. In the “Think big! Complex energy efficiency projects ”was awarded to the tool technology of sister companies Overath SLM and Overath EPP. The energy savings achieved are 86% in tool manufacture and 79% in use in plastics processing.

The central idea is to use an innovative 3D printing technology based on selective laser melting (SLM). This process used by Overath SLM saves material and reduces the weight of the tools. In addition, stainless steel is used instead of energy-intensive aluminum. In this way, a high level of energy and CO2-Saving can be achieved. In addition to the energy and material savings in the manufacture of the tools, there are considerable advantages over conventional technologies, especially when they are used to produce particle foams.

The 3D printing technology makes it possible to achieve conformal cooling in the tool made of stainless steel, thus reducing the amount of energy required for cooling by up to 80% and reducing the consumption of cooling water. The tool is cooled, similar to an injection molding tool, via internal cooling channels with a wall thickness of just 1 mm. This means that the mass of the tool material to be tempered is much lower than with conventional tools. In addition, with SLM technology, it is possible to make significantly more openings through which steam can escape. Both of these reduce the cycle time considerably. In the near future, the Zeppy housings will also be manufactured in such an additively manufactured foaming tool.

At a glance

Overath EPP in Oebisfelde. Image Overath

Overath SLM, Lohmar, and Overath EPP, Oebisfelde, are part of the Overath Group. Overath SLM is responsible for additive manufacturing (3D printing - Selective Laser Melting) of metal components and uses this technology in the toolmaking sector. Overath EPP is a processor of expanded polypropylene (EPP) for a wide range of applications. With around 60 employees, the family company produces custom-made built-in parts for the automotive industry in series. In addition, the company produces multifunctional insulating boxes, sporting goods and reusable transport packaging made of EPP for a wide variety of fields of application.

The digital sound system

The loudspeaker housing is made of EPP and is glued with a sealing compound. With the real-time audio processing, the audio signal is processed so that the housing and the PVC membrane vibrate and generate the sound. Image: Zeppy

The housing and a special sound technology are the basis for the impressive full sound of the Soundbuddys. While in conventional, analog loudspeakers the sound is generated by the vibration of a membrane, in the Zeppy this key role is played by a sheet made of foamed PVC from the manufacturer 3A Composites, Steinhausen, Switzerland. However, the signal from the transmitter is processed digitally in the sound system. “Drivers are built into the housing that make the top plate vibrate. With this forex record, we not only transmit the sound, we use it to make the music.

So-called real-time audio processing is used to make it sound appealing and inspiring, ”explains Kubisz. The input signal is digitally processed in such a way that it is optimally audible in this sound system. "We are proud that with Bongiovi Acoustics, based in Florida, we were able to win the partner for real-time sound equalization." The company specializes in digitally processing audio signals in the desired space and material, for example in aircraft interiors or in cars. to create the best possible acoustics. For this purpose, the interior cladding is equipped with appropriate drivers that transmit the signal to the cladding material in a coordinated manner. The entire interior cladding becomes a source of sound.

In addition, the PVC plate requires very little stroke compared to conventional loudspeakers in order to produce a rich sound. “This is advantageous in terms of service life,” says Reichl, “because the slight movement of the plate also requires little energy. It is possible to listen to music for up to 24 hours with one battery charge. "


Listen to music underwater

The housing is waterproof and also allows fun in the bathroom. Image: Zeppy

Another effect is that the loudspeaker can transmit the sound via the membrane and the EPP housing onto and into the water as well as to other surfaces that can be used acoustically. The speaker system is waterproof and floats thanks to the closed-cell material structure of the EPP. The material can be processed in various hardnesses, from 25 g / L to 300 g / L. "A component with a density of 300 g / L comes very close to an injection-molded part," explains Reichl. However, the Zeppy case is 93% air. “You can use it to listen to music in the pool or in the bathtub below the waterline,” says Kubisz, describing the possible uses. A conventional loudspeaker does not tolerate moisture and is usually not waterproof, the membrane would only produce distorted tones in contact with water.

Music experience for the hearing impaired

"But for me the best thing about our system is that deaf people can almost hear and feel music with it," says Reichl happily. Thanks to the freely suspended membrane, the Zeppy can be attached to surfaces or the human body, and it can even be placed directly behind the head. “As a result, the vibration of the membrane is transmitted directly to the skull bone. This is interesting, for example, for seniors who are hard of hearing but have an intact inner ear. ”Zeppy also benefits people with autism, as a positive change in mood can be brought about by simply“ touching the music ”. "The sound of the Zeppy is much more than what you would expect from a portable speaker - the way you experience the sound is extraordinary," says inventor Kubisz.

The loudspeaker can transmit the vibrations through structure-borne sound and at the same time serves as a massage system. This means that music can not only be heard, but also felt. Image: Zeppy

The technology is especially valuable for dancers, because with Zeppy the hearing and the non-hearing can dance together. “The frequency range of the Soundbuddy's is much wider than that of implants for the hearing impaired, so that the music actually sounds like music and not like a pulp of tones,” says Reichl, describing the effect. “We see people at trade fairs who take off their hearing aids and then listen to music with the Zeppy. You never forget this glow in your eyes. And it's very difficult to convey this feeling to people who have not tried and experienced it themselves. "

Elasticity brings stability

Another key advantage of EPP is its ability to absorb energy, which helps, for example, in automotive components to mitigate the impact in a crash. This material characteristic protects the interior of the loudspeaker against damage in the event of a fall. Reichl reports on case studies from a height of three meters, after which no damage to the Zeppy was detectable.

At the same time, this elasticity of the material requires a suitable joining technique. A stiff adhesive was used for the first prototypes. Over time, it turned out that the flexibility of the housing caused the adhesive connection to leak. “In the meantime we have a permanently elastic sealant in use that never really sticks and thus follows the movements. In this way, the housing remains tight, ”says Reichl. The glue is applied purely manually, a primer is not necessary.

“The sound of the Zeppy is much more than what you would expect from a portable speaker, the way you experience the sound is extraordinary.

Raffael Kubisz, founder and managing director of the Zeppy company, Prinzersdorf, Austria.

An approach to design for recycling

The loudspeaker consists of four manually assembled parts, most of which can be recycled after use. Kubisz explains: “We always focus on quality and a long service life. Nevertheless, in the long term it is conceivable that we will reuse individual components. We are still at the beginning here, especially since the return rate is really minimal due to defects. Very soon it will be possible, however, that the user will be able to dismantle the loudspeaker at the end of its service life in order to feed the components and the battery to the appropriate material cycle. "

In particular, the housing made of pure polypropylene can very easily be returned to the recycling cycle. Reichl makes it clear: “The advantage of polypropylene is that it is foamed solely through the pressure difference in the mold without blowing agents or foreign matter. It can therefore be recycled as pure EPP with virtually no loss of quality. ”The Zeppy housing is made of Arpro, an EPP from the supplier JSP, Tokyo, Japan. Jens Grunwald, Product Manager for Sustainability for Europe, Africa and the Middle East, says: “Arpro was the answer to many of the design questions that Zeppy asked. It offers an extraordinary combination of properties and the EPP is recyclable. ”This is why Zeppy is also available in a version with Arpro 35 Ocean. The material consists of 15% EPP recyclate that is made from recycled waste from the maritime industry such as fishing nets and ropes. This gives the material its special color. “The production of Arpro 35 Ocean emits seven percent less CO compared to virgin materialproduced ”, explains the product manager.

A sound system with potential

The team of inventors Kubisz and Reichl has drawn up a sophisticated business plan for their start-up, which has already been presented in a TV-effective start-up competition in Austria.“After the broadcast in May 2020, we were sold out within three days and around 4,000 units are on the market to date. That shows us that we are on the right track with our product, ”Reichl formulates. Despite the higher price compared to the market, the Soundbuddy is well received by consumers due to its convincing properties.

Kubisz gives an outlook on how the technology can be implemented in other products. “We are currently working on a cool box into which we want to integrate Zeppy. The container then acts as a horn and amplifies the sound. ”He emphasizes:“ We are not lacking in ideas. There will be other sound systems. As a start-up, we concentrate on a few product ideas that can be implemented with our capacities. ”This also includes an application in the health care / lifestyle market that is being implemented with a partner in Hong Kong. “Since the entire speaker box vibrates, it also has a massage function. We took advantage of this property with a provider of relaxation technology. To do this, the loudspeaker is integrated into a cushion made of soft polyurethane foam and controlled via an app, ”reports Reichl. A suitable yoga mat should complement the system. "We are also using a system in a vegetative coma department of a hospital in a mini-study," adds Kubisz. Further applications for the gaming market, for example for sound and effects in special seating furniture, are conceivable.

Sound design in the vehicle

The Soundbuddy is also robust enough for outdoor sports. Image: Zeppy

The founding team also sees application potential in the automotive, rail and bus sectors. Here the Zeppy technology could fill the room with sound without openings, quasi “speakerless”. “That opens up completely new design possibilities,” says Kubisz. EPP foams are already an integral part of interior design and could gain in importance in the new electric drive concepts with a view to weight and sound. In addition, the near-field sound characteristics allow you to create sound zones and provide individual sound reinforcement.

The application possibilities of the Soundbuddys are far from exhausted. It will therefore be interesting to see what the founders are still implementing and with which partners future products for medical technology, for the vehicle industry and for other areas of application will be brought onto the market. "You will hear a lot more about the Zeppy, literally," said Reichl. The Kubisz and Reichl team is convinced of this.