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Session C Friday, November 30 2:00 pm-4:30 pm
Chair: Wolfgang J. Klippel, Klippel GmbH, Dresden, Germany

2:00 pm

C-1 Prediction of Speaker Performance at High Amplitudes

Wolfgang J. Klippel, Klippel GmbH, Dresden, Germany

A new method for the numerical simulation of the large signal performance of drivers and loudspeaker systems is presented. The basis is an extended loudspeaker model considering the dominant nonlinear and thermal effects. The use of a two-tone excitation allows the response of fundamental, dc component, harmonics, and intermodulation components to be measured as a function of frequency and amplitude. After measurement of the linear and nonlinear parameters, the electrical, mechanical, and acoustical state variables may be calculated by numerical integration. The relationship between large signal parameters and nonlinear transfer behavior is discussed by modeling two drivers. The good agreement between simulated and measured responses shows the basic modeling, parameter identification, and numerical predictions are valid even at large amplitudes. The method presented reduces time-consuming measurements and provides essential information for quality assessment and diagnosis. The extended loudspeaker model also allows prediction of design changes on the large signal performance by changing the model parameters to reflect the driver design changes. The incorporation of nonlinear parameters into the loudspeaker model allows optimization in both the small and large signal domains by model prediction.

Convention Paper 5418


2:30 pm

C-2 Loudspeaker Nonlinear Parameter Estimation: An Optimization Method

Ryan J. Mihelich, Harman/Becker Automotive Systems, Martinsville, IN, USA

A new method for the estimation of the nonlinear modeling parameters of a electrodynamic loudspeaker is presented. Measurements of time-domain voice coil displacement are compared with the predicted displacement from a modeled loudspeaker. An optimizer adjusts the coefficients of the functions describing the nonlinear parameters. Loudspeaker nonlinear parameters are obtained through minimization of error between the measurements and the modeled response. The resulting nonlinear model yields good agreement with measured data over a broad frequency and amplitude range.

Convention Paper 5419


3:00 pm

C-3 Computer-Aided Design of Electrodynamic Loudspeakers by Using a Finite-Element Method

Martin Rausch, Manfred Kaltenbacher, Hermann Landes and Reinhard Lerch, University of Erlangen-Nuremberg, Erlangen, Germany
Leonhard Kreitmeier and Gerhard Krump, Harman/Becker Automotive Systems GmbH, Straubing, Germany

This paper demonstrates the applicability of an efficient numerical calculation scheme in the computer-aided design of electrodynamic loudspeakers. This modeling scheme is based on a finite element method (FEM) and allows the precise calculation of the electromagnetic, mechanical, and acoustic fields including their couplings. Furthermore, nonlinear effects in the mechanical behavior of the spider as well as magnetic nonlinearities due to the nonhomogeneity of the magnetic field are taken into account.

Convention Paper 5420


3:30 pm

C-4 The Virtual Loudspeaker Cabinet

J. R. Wright, KEF Audio (UK) Ltd., Maidstone, Kent, UK

This paper describes a method of increasing the acoustic compliance of a loudspeaker cabinet by introducing activated carbon into the enclosure. The process is explained, and working examples are discussed.

Convention Paper 5421


4:00 pm

C-5 Acoustical Elements for Multi-Band Articulated Line Arrays

Douglas J. Button and Mark E. Engebretson, JBL Professional, Northridge, CA, USA

For large-scale sound reinforcement, due to the limited bandwidth and output capability of typical full range transducers, there is a need to use multiple bands of transducers specifically designed for higher output with adequate bandwidth. The transducers then need to be arranged in a manner that takes advantage of summing effects within the band, yet minimizing acoustical compromises that arise because of physical constraints. It is important that devices not interfere with one another while maintaining the desired horizontal dispersion over as wide a bandwidth as possible. This work outlines a configurational solution along with specific acoustical wave shaping devices that are used to build a large articulated line array with 3 passbands.

No Convention Paper Printed

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