. Elements of acoustical engineering. Electro-acoustics; Sound. EFFICIENCY 147 where B = flux density, in gausses, / = length of wire in the voice coil, in centimeters, and Zm = mechanical impedance of the vibrating system, in mechanical ohms, at the point/^ Fig, T^aTma ' T hJ VOICE COIL CUECTRICAL CIRCUIT EQUIVALENT CIRCUIT OF THE MECHANICAL SYSTEM. CROSS-SECTIONAl. VIEW Fig. Cross-sectional view of a horn loud speaker, the electrical circuit and equivalent electrical circuit of the mechanical system. In the voice coil circuit: e the internal voltage of the generator, teg the intern
. Elements of acoustical engineering. Electro-acoustics; Sound. EFFICIENCY 147 where B = flux density, in gausses, / = length of wire in the voice coil, in centimeters, and Zm = mechanical impedance of the vibrating system, in mechanical ohms, at the point/^ Fig, T^aTma ' T hJ VOICE COIL CUECTRICAL CIRCUIT EQUIVALENT CIRCUIT OF THE MECHANICAL SYSTEM. CROSS-SECTIONAl. VIEW Fig. Cross-sectional view of a horn loud speaker, the electrical circuit and equivalent electrical circuit of the mechanical system. In the voice coil circuit: e the internal voltage of the generator, teg the internal resistance of the generator. L the inductance of the voice coil. rsD the damped resistance of the voice coil, zem the motional impedance. In the equivalent electrical circuit of the mechanical system: mA and tma the mass and radiation resistance due to the air load on the back of the diaphragm, mc and mD the mass of the voice coil and diaphragm. Cms and Cmi the compliance of the suspension and air chamber, zmh the mechanical impedance at the throat of the horn, zme the mechan- ical impedance due to the electrical circuit, /m the force generated in the voice coil, /mo the force of the mechanical generator. The efficiency jjl, in per cent, is fEM M = rED + rEM X 100 where rsM = resistance component of the motional resistance, in ohms, and rsD = damped resistance of the voice coil, in ohms. In the equivalent electrical circuit, Fig. , the impedance Zm ^.t/m is given by Zm = jo^rriA + Tma + jo)?nc + jc^mo + -. 1 + Zmh JwCms J(^CmiZmh + 1 where pja = mass of the air load on the back of the diaphragm, in grams, mc = mass of the voice coil, in grams, jnr, = mass of the diaphragm, in grams, rMA = resistance load on the back of the diaphragm, in mechanical ohms, Cms — compliance of the suspension, in centimeters per dyne, Cmi = compliance of the air chamber, in centimeters per Please note that these images are extracted from scanned page images that may have been
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