AES San Francisco 2010
Poster Session P14

P14 - Loudspeakers and Microphones

Friday, November 5, 4:30 pm — 6:00 pm (Room 226)

P14-1 Coaxial Flat Panel Loudspeaker System with Dynamic Push-Pull DriveDrazenko Sukalo, DSLab - Device Solution Laboratory - Munich, Germany
After the successful introduction of the flat television, acousticians are concerned with the design of a “full-range” flat panel loudspeaker. A new design with low manufactured depth, consisting of an array of two conventional cone drivers and a transmission line and the method for driving of them is presented. The main aim was to build a small-sized flat panel box but with extended low frequency response and low distortion output because of the extended liner diaphragm excursion. The PSpice-OrCAD® simulator was used to represent a distributed model of a transmission line. The results of the simulation show the influence of the parameters of the transmission-line enclosure on the impedance curve and resonant frequency of the woofer driver. Among others, this paper is concerned with an active filter design for driving loudspeaker drive units in an appropriate phase relationship in the low frequency region, by means of implementing of DPP drive. A prototype of the flat panel loudspeaker is built according to the described design concept and the results of sound pressure level measurement are presented. The design result from work performed for DSLab and is subject to the referenced patent.
Convention Paper 8235 (Purchase now)

P14-2 A Novel Universal-Serial-Bus-Powered Digitally Driven Loudspeaker System with Low Power Dissipation and High FidelityHajime Ohtani, Akira Yasuda, Kenzo Tsuihiji, Ryota Suzuki, Daigo Kuniyoshi, Hosei University - Koganei, Tokyo, Japan; Junichi Okamura, Trigence Semiconductor - Chiyoda, Tokyo, Japan
We propose a novel digitally driven loudspeaker system in which a newly devised mismatch shaper method, multilevel noise shaping dynamic element matching, is used to realize high fidelity, high sound power level, and low power dissipation. The unit used for the mismatch shaper method can easily increase the number of sound pressure levels with the aid of an H-bridge circuit, even when the number of sub-speakers is fixed. Further, it reduces the noise caused by quantization and loudspeaker mismatches and decreases the switching loss. The output sound power level equipped with six voice coils is 94 dB/m when a 3.3-V universal-serial-bus power supply is used exclusively. The power efficiency is 95% at 0 dBFS and 75% at –10 dBFS.
Convention Paper 8236 (Purchase now)

P14-3 Loudspeaker Rub Fault Detection by Means of a New Nonstationary Procedure TestGerman Ruiz, Vicent Sala, Miguel Delgado, Juan Antonio Ortega, UPC-Universitat Politecnica de Catalunya - Terrassa, Spain
This paper addresses rub defect loudspeaker detection. The study includes a simulation with a rub model based on classical static coulomb friction added to the loudspeaker nonlinearities parametric model to demonstrate the current signal viability to rub failure detection. The electric current signal is analyzed by means of Zhao-Atlas-Marks distribution (ZAMD). A failure extractor based on relevant harmonic ZAMD frequency regions segmentation and Mahalanobis distance is presented. The simulation and experimental results show the goodness and reliability of rub detection method presented.
Convention Paper 8237 (Purchase now)

P14-4 Contributions to the Improvement of the Response of a Pleated LoudspeakerJaime Ramis, Rita Martinez, Acustica Beyma S.L. - Moncada, Valencia, Spain; E. Segovia, Obras Públicas e Infraestructura Urbana - Spain; Jesus Carbajo, Jaime Ramis, Universidad de Alicante - Alicante, Spain
In this paper we describe some results that have led to the improvement of the response of an Air Motion Transformer loudspeaker. First, it is noteworthy that it has been found an approximate analytical solution to the differential equations system that governs the behavior of the moving assembly of this type of transducer, being this valid when the length of the pleat is much greater than the radius of the cylindrical part. This solution is valid for any type of analysis (static, modal, and harmonic), and the modes are significantly simplified assuming the hypothesis above mentioned. In addition, we have analyzed the influence of the thickness and the shape of perforation of the pole piece in the frequency response of the loudspeaker.
Convention Paper 8238 (Purchase now)

P14-5 Exploring the Ultra-directional Acoustic Responses of an Electret Cell Array LoudspeakerYu-Chi Chen, Wen-Ching Ko, National Taiwan University - Taipei, Taiwan; Chang-Ho Liou, National Taiwan University - Taipei, Taiwan, Industrial Technology Research Institute, Hsinchu Taiwan; Wen-Hsin Hsiao, Chih-Chiang Cheng, Wen-Jong Wu, Pei-Zen Chang, National Taiwan University - Taipei, Taiwan; Chih-Kung Lee, National Taiwan University - Taipei, Taiwan, Institute for Information Industry, Taipei, Taiwan
In recent years, novel thin-plate loudspeakers have triggered much interest. Applications in areas such as 3C peripherals, automobile audio systems, and home theater have been actively discussed. However, the acoustic directivity of a thin-plate loudspeaker depends on the frequency response. At this time, thin-plate loudspeakers have poor directivity. However, if this limitation can be overcome, thin-plate loudspeakers can find useful applications such as in museums, supermarkets, or exhibition areas that require a channeling the sound to a particular area or location without affecting nearby areas or unintended audiences. From previous studies, electret cell arrays have been confirmed to be an excellent flexible flat loudspeaker since it can create high performance sounds in a mid to high frequency range. An electret loudspeaker can generate ultra-directional audible sound by adjusting the array size, amplitude modulation, and layout structure.
Convention Paper 8239 (Purchase now)

P14-6 A Soundfield Microphone Using Tangential CapsulesEric Benjamin, Suround Research - Pacifica, CA, USA
The traditional soundfield microphone is a tetrahedral array of pressure gradient microphones, the outputs of which are linearly combined in order to realize signals that are proportional to co-located microphones, one with omnidirectional sensitivity and three orthogonal microphones with figure-of-eight sensitivity. This configuration works well and has been the basis of commercial products for a number of years. Recently, an alternative array type has been disclosed [2,3] by Craven, Law, and Travis, comprised of pressure gradient sensors arranged with their principle axes oriented tangentially with respect to the center. Additional analysis has been performed and several prototypes were constructed and evaluated.
Convention Paper 8240 (Purchase now)

P14-7 A 2-Way Loudspeaker Array System with Pseudorandom Spacing for Music ConcertsYuki Ayabe, Saburo Nakano, Tokyo City University - Setagaya-ku, Tokyo, Japan; Kaoru Ashihara, Advanced Industrial Science and Technology - Tsukuba, Japan; Shogo Kiryu, Tokyo City University - Setagaya-ku, Tokyo, Japan
A 96-channel loudspeaker array system that allows real-time control of sound field has been developed for live musical concerts. Multiple sound focused at different points can been generated and controlled independently using the system. The variable delay circuits, the controller of the power amplifier, and the communication circuit between the hardware and the computer are implemented in FPGAs. In order to extend the frequency range and reduce the spatial aliasing, the loudspeaker array is assembled by two-way loudspeakers with pseudorandom spacing.
Convention Paper 8241 (Purchase now)

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