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Bulk download - click topic to download Zip archive of all papers related to that topic:   Applications & Audio Education    Audio Applications    Audio Coding, Analysis, and Synthesis    Audio Education    Audio Processing and Effects – Part 1    Audio Processing and Effects – Part 2    Audio Quality Part 1    Audio Quality Part 2    e-Brief Posters—1    e-Brief Posters—2    Loudspeakers-Part 1    Loudspeakers-Part 2    Measurements    Perception – Part 1    Perception – Part 2    Perception – Part 3    Posters: Analysis/Synthesis    Posters: Applications    Posters: Audio Coding and Quality    Posters: Audio Processing/Audio Education    Posters: Measurement    Posters: Modeling    Posters: Perception    Posters: Spatial Audio    Posters: Transducers    Signal Processing/Audio Effects & Instrumentation/Measurements/Forensics    Spatial Audio    Spatial Audio-Part 1    Spatial Audio-Part 2    Spatial Audio-Part 3    Transducers & Psychoacoustics   

 

Maximizing Efficiency in Active Loudspeaker Systems

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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.

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How Do We Make an Electrostatic Loudspeaker with Constant Directivity?

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The idea of broadening the directivity pattern of a push-pull electrostatic loudspeaker by partitioning the stators into concentric annular rings, which are connected to tappings along a delay line, isn't new. However, the delay line has traditionally been attenuated to avoid response irregularities due to the finite size of the membrane. An alternative approach is presented here whereby a constant-impedance delay line is configured to imitate an oscillating sphere, which is an ideal constant-directivity dipole source that needs no attenuation. Walker's equation for the on-axis pressure does not account for the effect of the delay line without taking the vector sum of the currents though all the rings, so a simple alternative that does is presented here.

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Analysis of Front Loaded Low Frequency Horn Loudspeakers

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The low frequency horn design procedures described by Keele and Leach are extended and generalized to cases where the horn is already specified, or where maximum output or the smoothest response is desired. The impact of finite-length horns is analyzed. A more detailed analysis of the high frequency range is given, where it is shown how the voice coil inductance can be taken into account to create a third order low pass filter of specified shape. A new analysis of reactance annulling is presented that significantly improves the performance above cutoff for a certain class of horns. Large signal behavior is touched upon, and finally, an analysis of the sensitivity of driver and system parameters is given.

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Design and Implementation of a High Efficiency Subwoofer

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The demand for battery driven loudspeakers is increasing but the challenge of efficient low frequency reproduction remains. An alternative approach to the conventional 4th order bandpass enclosure design for a subwoofer to achieve a high peak in the passband and increase voltage sensitivity is investigated. The response is corrected with DSP to ensure a flat response in the passband. The results proved that this approach can increase the voltage sensitivity dramatically, reaching an average sensitivity of over 100 dB in the passband from 45 Hz to 90 Hz. It also showed that the design is sensitive to construction errors. Precise assembling is required to achieve satisfactory results while small errors can ruin the purpose of the design.

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Parameterization of Micro Speakers Used in Cell Phones and Earbuds

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Loudspeaker parameterizations based on measuring a transfer matrix is presented. This approach produces nine complex frequency dependent functions. While Thiele-Small parameters only capture the first piston mode of a moving coil speaker, the transfer matrix approach captures all the linear behavior of the speaker, including the diaphragm modes and internal geometry. Predictions of baffled response of two speakers are presented with the transfer matrix parameters producing better results than the Thiele-Small parameters, especially at high frequencies. The SAATI "Ares" acoustic simulator uses the transfer matrix parameters for effective simulation of complete devices, including proper porting geometry and dampening acoustic meshes for better audio tuning.

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A Fast And Efficient Model for Transmission Line Loudspeakers

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Transmission Line loudspeakers use a tube behind the driver that is lined, or filled, with absorber to remove the rear radiation. They also use the resonances of the pipe to support the radiation of the driver and reduce displacement at low frequencies. While lumped element models are used for modeling sealed and vented box enclosures, they cannot be used for transmission line loudspeakers because they cannot be accurately modeled as a lumped element. Finite Element and Boundary Element models can be used but they are complex and computationally expensive. A cascaded two port method has been developed that can model varying tube area and absorption. It has been evaluated against acoustic measurements and shown to provide accurate predictions.

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Acoustic Power Based Evaluation of Loudspeaker Distortion Measurements

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Traditionally, drive-unit related distortion figures are evaluated “on-axis.” This method leads to straightforward results as long as the frequency of the analyzed distortion component stays below the driver’s modal break-up region. When the distortion component is entering the drive-unit’s break-up region an on-axis based distortion analysis approach can become difficult if not meaningless. Therefore an alternative method is proposed which makes use of acoustic harmonic distortion sound power values, instead of sound pressure levels acquired in a single observation point (on-axis). These acoustic power values are derived from high resolution directivity data for the fundamental-, 2nd- and 3rd-harmonic-distortion components. Results are shown for different kinds of drive-units and the implications are discussed.

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Anti-Rattle System Loudspeaker Device

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On the basis of loudspeaker cabinets and panels vibration problems, this paper deals with a new dynamic loudspeaker device capable to reduce mechanical vibrations transmitted to the panel where it is fixed. Virtual 3D prototype is designed and optimized by simulations. Simulations were carried out using analytical and finite element methods. A working prototype was realized, measured and then tested on a panel, in order to evaluate vibrations reduction.

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FEM Thermal Model of a Compression Driver: Comparison with Experimental Results

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A complete time domain thermal model of a compression driver was developed using COMSOL Multiphysics in order to predict heating phenomena and minimize potential damage. Heat transfer in the model relies on conduction, natural convection, and radiation all together ensuring a rigorous approach. Considerations accounting for power compression are also included in order to provide detail in the temperature prediction through time. Results are satisfactory and represent the outcome of an accurate method to predict operation limits of such devices, together with the change of magnetic induction in the air gap due to thermal effects.

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Dynamic Driver Linearization Using Current Feedback

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It is well known that the electromechanical parameters of a dynamic driver can be modified through current feedback to suit the requirements of the available enclosure size and desired bandwidth, with a reduced distortion as a commonly observed beneficial effect. However, especially when designing sealed enclosures it is possible to select the loudspeaker parameters from a continuum of combinations of effective moving mass, damping resistance, and compliance. This paper describes optimization of electrical source parameters to improve the linearity based on numerical solution of the nonlinear equation of motion of the driver using the measured driver parameters.

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                 Search Results (Displaying 1-10 of 121 matches)
AES - Audio Engineering Society