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There are number of interrelated factors that need to be considered in the design of direct radiator loudspeakers.These include electro-acoustic efficiency, uniformity of frequency response and their dependence on electrical and motional impedance of the system.The major objective our work is to provide engineers with design parameter ranges to optimize to enhance the efficiency of direct radiator loudspeakers. A set of two independent algorithms, concurrently with a set of functions, to generate ready-reckoners that compute an appropriate set of parametersis offered. Parameters are optimized in pairs to enhance efficiency.The parameters viz. diaphragm stiffness, transformation factor and moving mass are optimized in varying combinations. The functions are based on the following characteristic responses: a) variation of efficiency with transformation factor at varying diaphragm stiffness and constant moving mass b) variation of efficiency with moving mass at varying diaphragm stiffness and constant transformation factor. Characteristics of above functions are examined vis-à-vis change in efficiency with pairs of concurrent parameters: i) transformation factor and diaphragm stiffness, and ii) moving mass and diaphragm stiffness.Also, characteristics of above functions (a) and (b) are examined vis-à-vis change in efficiency with change in frequency using appropriate routines. Data obtained using simulationis fitted to appropriate polynomials. Polynomial coefficients are compared and characteristic profiles are obtained over the above range of parameters. Efficiency and the mechanical impedance are examined over a range of randomly generated frequencies.At lower frequencies, the variation of efficiency with moving mass at different diaphragm stiffness, is valuable e.g. at a frequency of 50 Hz and a stiffness of 2000 N/m the efficiency maximum is 33% when the moving mass is 0.015 kg whereas to achieve the same efficiency maximum at a stiffness of 3000 N/m the moving mass needs to be 0.025 kg.The change in efficiency with transformation factor at varying stiffness shows interesting results: For a frequency of 50 Hz and a moving mass of 0.05 kg, the efficiency shows valuesranging from 2.6% to 30% for a transformation factor of 5.5 Wb/m as the diaphragm stiffness varies from 1000 N/m-6000 N/m,whereas the variation in efficiency is 2.6% to 48% within the same stiffness range as the transformation factor changes from 5.5-9.5 Wb/m. However, as we extend the range to 7000 N/m, the efficiency significantly lowers from 30% to 15% for 5.5 Wb/m and from 48% to 32% for 9.5 Wb/m.
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