The Loudspeaker Specialist www.visaton.com Basic principles of exciter-technology Table of contents 1. Functionality of the VISATON Exciter 2. Mounting the VISATON Exciter 3. Advantages and disadvantages of the exciter-technology 4. Frequently asked questions (FAQ) 1. Functionality of the VISATON Exciter An exciter, also known as bodyshaker, is basically a loudspeaker without a membrane. It mainly consists of 3 components: the oscillating mass (1), the contact pins (2) to connect to the amplifier, and the mounting plate (3) to hook up to the surface to be excited. 1. Oscillating mass 2. Contact pins 3. Mounting plate By applying a voice- or music signal to the contact pins, the oscillating mass starts shaking with the frequency of the applied signal. This oscillation is transmitted to the mounting plate and from there on to the surface the exciter sticks to. Thus, the excited surface will emit the voice- or music signal. 201004 / SB Basic principles of VISATON exciter-technology VISATON All rights reserved including reproduction in whole or in part VISATON GmbH & Co. KG Ohligser Strae 29-31 42781 Haan Tel.: 02129 / 552 - 0 Fax: 02129 / 552-10 E-Mail: visaton visaton.comThe Loudspeaker Specialist www.visaton.com The functionality of an exciter is therefore pretty similar to the functionality of a conventional loudspeaker. How- ever, there are some differences in how the sound is emitted. The excited surface is, compared to a lightweight cone membrane, very large and heavy, and thus unable to oscillate coherently. That means, not every point of the surface moves into the same direction with the same amplitude at the same time. The exciter generates a bending wave which propagates towards the edge of the excited plate, where it is reefl cted back towards the ex - citer. To illustrate this behavior, one can imagine a stone thrown into a basin of water. From the point where the stone hits the surface of the water, a circular bending wave propagates towards the seam of the basin, where it is reflected. The original wave and the reflected wave interfere with each other, causing a chaotic wave-pattern on the water surface. The same applies to the excited surface: The original wave from the exciter interferes with the reflected waves from the edges of the plate, resulting in an incoherent emission of sound. This incoherent sound emission is the main reason for the very wide, uniformly distributed sound field of an excited surface. As one can easily imagine, the quality of the reproduced music- or voice signal is strongly dependent on the char- acteristics of the excited surface, such as material, shape and dimensions. 2. Mounting the VISATON Exciter Mode of mounting Depending on the type of exciter that is used, the exciter is attached to the surface by means of gluing and/ or screwing. Generally, a clean and even surface is required. The whole mounting plate of the exciter is to be seated solidly onto the excited surface. For gluing an exciter onto a surface, two component glues, silicone or a long-term stable double-sided adhesive tape suit best. The consistency of the surface must always be taken into account when choosing the right glue. Exciter which provide an inserted nut instead of the flat mounting plate, require a matching threaded bolt for in- stallation, that needs to be attached firmly to the excited surface. Position of mounting In many cases, a mounting position slightly off-center of the excited surface gives good results. Because the acoustical results are strongly dependent on material properties and the shape of the excited surface, listening tests and measurements are inevitable to determine the optimal mounting position. For testing different mount- ing positions, a standard double-sided adhesive tape can be used. In order to test positions at the rear side of a surface that are difficult to access, the exciter can provisorily be mounted at the equivalent position on the front side of the surface, which doesnt affect the sound output. Materials and shapes of the excited surface The larger the excited plate, the better the reproduction of low frequencies, the sound output is more volu- minous The smaller the excited plate, the weaker the reproduction of low frequencies, the sound output is less vo- luminous The efficiency factor (sound pressure level compared to input power) decreases with increasing weight of the excited plate. The plate therefore is preferably lightweight The plate ought to be rigid The plate should consist of a non-magnetic material. The exciter contains a permanent magnet which would cause a harmful pre-tension to the suspension of the exciter if attached to a magnetic plate The appearance of the excited surface has a great impact on the sound output. Devices with few reinforcing structures and large surfaces qualify best. Anyways, many different types of devices and surfaces are suit- able for the use of exciters. In any case, measurements and listening tests are the most reliable methods to determine the best operating surface for an exciter 201004 / SB Basic principles of VISATON exciter-technology VISATON All rights reserved including reproduction in whole or in part VISATON GmbH & Co. KG Ohligser Strae 29-31 42781 Haan Tel.: 02129 / 552 - 0 Fax: 02129 / 552-10 E-Mail: visaton visaton.com