AES Milan, Italy
144th AES Convention in Milan
SEMINAR after AES Milan: "Cone Vibration and Sound Radiation" (May 28th + 29th, 2018 in Loria, Italy)
P01-1 Maximizing Efficiency in Active Loudspeaker Systems (Wolfgang Klippel)
Wednesday, 23rd May 2018 @ 9:30 - 10:00
Increasing the efficiency of the electro-acoustical conversion is the key to modern audio devices generating the required sound output with minimum size, weight, cost and energy. There is unused potential for increasing the efficiency of the electro-dynamical transducer by using a nonlinear motor topology, a soft suspension and cultivating the modal resonances in the mechanical and acoustical system. However, transducers optimized for maximum efficiency are more prone to nonlinear and unstable behavior. Nonlinear adaptive control can compensate for the undesired signal distortion, protect the transducer against overload, stabilize the voice coil position and cope with time varying properties of the suspension. The paper discusses the design of modern active systems that combine the new opportunities provided by software algorithms with the optimization of the hardware components in the transducer and power amplifier.
P05-3 Fast and Sensitive End-of-Line Testing (Stefan Irrgang)
Wednesday, 23rd May 2018 @ 15:15 - 15:45
Measurement time is a crucial factor for the total cost and feasibility of end-of-line quality control. This paper discusses new strategies minimizing the test time for transducers and audio systems while ensuring high sensitivity of defect detection, extracting comprehensive diagnostics information and using available resources in the best possible way. Modern production lines are fully automated and benefit highly from high speed testing. Optimal test stimuli and sophisticated processing in combination with multi-channel test design are the key factors for smart testing. Appropriate acoustical, mechanical and electrical sensors are discussed and suggested. Furthermore, parallel or alternating test schemes reduce the overall test time. Finally, typical concerns and pitfalls when testing at high speed are addressed and illustrated by measurement results.
P05-4 Optimal Material Parameter Estimation by Fitting Finite Element Simulations to Loudspeaker Measurements—William Cardenas
Wednesday, 23rd May 2018 @ 15:45 - 16:15
Important characteristics for the sound quality of loudspeakers like frequency response and directivity are determined by the size, geometry, and material parameters of the components interfacing the acoustic field. The higher-order modes after cone break-up play an important role in wideband transducers and require a careful design of the cone, surround, and other soft parts to achieve the desired performance. Finite Element Analysis is a powerful simulation tool but requires accurate material parameters (complex Young's modulus as a function of frequency) to provide meaningful results. This paper addresses this problem and provides optimal material parameters by fitting the FEA model to an existing loudspeaker prototype measured by Laser vibrometry. This method validates the accuracy of the FEA simulation and gives further information to improve the modeling.
T08 Benefitting from New Loudspeaker Standards (Wolfgang Klippel; Prof. Shen of Nanjing University, PR China)
Wednesday, 23rd May 2018 @ 16:30 - 18:00
This tutorial focuses on the development of new IEC standards, addressing conventional and modern measurement techniques applicable to all kinds of transducers, active and passive loudspeakers and other sound reproduction systems. The first proposed standard (IEC 60268-21) describes important acoustical measurements for evaluating the generated sound field and signal distortion. The second standard (IEC 60268-22) is dedicated to the measurement of electrical and mechanical state variables (e.g. displacement), the identification of lumped and distributed parameters (e.g. T/S) and long-term testing to assess power handling, thermal capabilities, product reliability and climate impact. The third standard (IEC 63034) addresses the particularities of micro-speakers used in mobile and other personal audio devices. The tutorial gives a deeper insight into the background, theory and practical know-how behind those standards.
T14 Perceptual and Physical Evaluation of Guitar Loudspeakers (Wolfgang Klippel)
Thursday, 24th May 2018 @ 10:45 - 12:15
Loudspeaker and headphones generate distortion in the reproduced sound that can be assessed by objective measurements based on a physical or perceptual model or just by a subjective evaluation performed in systematic listening tests. This tutorial gives an overview on the various techniques and discusses the way how measurement and listening can be combined by auralization techniques to give a more reliable and comprehensive picture on the quality of the sound reproduction. The separation of signal distortion in speech signals allows to assess signal distortion which are for most stimuli below the audibility threshold. Further analysis of the separated distortion signals gives clues to identify the physical root cause of loudspeaker defects which is very crucial for fixing design problems.
T06 Optimizing Transducer Design for Systems with Adapative Nonlinear Control (Gregor Höhne)
Friday, 25th May 2018 @ 15:15 - 16:30
Modern loudspeakers increasingly incorporate digital signal processing, amplification and the transducer itself in one unit. The utilized algorithms not only comprise linear filters but adaptively control the system, deploying measured states and complex models. Systems with adaptive nonlinear control can be used to equalize, stabilize, linearize and actively protect the transducer. Thus, more and more demands can be taken care of by digital signal processing than by pure transducer design, opening new degrees of freedom for the latter. The tutorial focuses on how this freedom can be utilized to design smaller and more efficient loudspeaker systems. Examples are given for how existing transducer designs can be altered to increase their efficiency and which new challenges arise when driving speaker design to its limits.