There are many underappreciated technologies in the world of audio engineering. One of them is the exciter or "structure-borne sound converter"! This technology opens up new avenues in the conception and implementation of audio solutions, promising unprecedented possibilities. Discover why you, an audio enthusiast, tinkerer or DIY speaker builder, want to take a closer look at exciters.
Exciters, or "structure-borne sound converters", are small, lightweight devices that create sound waves by causing a surface to vibrate. In contrast to conventional loudspeakers, which generate sound through vibrations in a cone-shaped diaphragm and in a loudspeaker housing, an exciter uses almost every imaginable surface as a resonance body.
Exciters open the door to completely new areas of application. You could turn a glass door, a table top, the underside of a chair seat or even the ceiling into a speaker – the possibilities are almost limitless.
Have you ever dreamed of not only hearing music, but also feeling and seeing it? This is possible with exciters. The direct vibration of the surfaces on which the exciters are attached creates an intense immersive sound experience that you can feel and hear.
Exciters are finding more and more applications in a variety of areas. Here are a few examples of where they are already being used:
Especially in cars, exciters offer a range of possible applications for high-quality sound within the interior of the vehicle. One important advantage is the considerable reduction in materials needed. A few exciters are enough to provide the performance of a larger number of conventional speakers. They are mounted directly on parts of the vehicle, such as the interior panelling or the window panes, and turn them into sound converters. The result is a room-filling sound experience that seems to come from different directions.
The use of exciters also reduces the need for extensive cabling. This simplifies vehicle design and contributes to leaner, more efficient vehicle architecture. Fewer cables means less weight, less installation time and fewer potential sources of error. So the use of exciters offers a clear win-win situation – optimised sound with reduced use of materials and less complexity.
As a loudspeaker with no diaphragm, an exciter consists of three main components:
Exciter technology is based on sound transmission. When an exciter causes a surface to vibrate, sound waves are created that propagate through the material. These vibrations are mechanical waves that are caused by the arrangement and movement of atoms and molecules in the material. Depending on the nature of the material and the excited surface, the sound produced can vary greatly. This is because the speed at which sound waves propagate in a material and how the material damps the vibrations affect how the sound is perceived.
The larger the plate, the fuller the sound, with an emphasis on the low-frequency components. Conversely, the sound appears thinner with smaller plates.
The weight of the plate is also important. Light plates are advantageous because the efficiency – the ratio between sound pressure levels and input power – decreases with increasing weight. Ideally, the plate should be rigid and made of a non-magnetic material. The reason is that exciters have a permanent magnet and would therefore be precharged.
The shape of the plate also has a big impact on the sound. Components with large surfaces often have a positive effect.
When wiring, you should make sure that the resonance of the cables does not cause any interference. The classic situation is where cables touch the mounting plate or a sensitive body in the vicinity due to the resulting movement. If necessary, covering the cables with foam helps.
There are a few things to consider when using exciters. Choose the soundboard carefully: it should be light, rigid and non-magnetic. Experiment with different shapes and sizes to find the ideal sound. Position the exciter so that it causes the largest possible area to oscillate.
Exciters or structure-borne sound converters are revolutionising audio technology. They make unique worlds of sound possible by transforming almost any surface into a speaker. Whether in architecture, marketing, art or medical technology, exciters are opening up innovative possibilities.
The relevance of the exciter for the automotive sector deserves special mention. Here they enable an immersive sound experience by transforming parts of the vehicle, such as the interior panelling or the window panes, into sound converters. They also reduce the use of materials and the complexity of the wiring, which contributes to more efficient vehicle architecture. Despite certain challenges, such as their dependence on the material and shape of the excited surface, it is clear that exciters are a future-oriented technology.
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