Electromagnetic driving system for telephone receiver

The functional qualities of such a receiver are determined by the efficiency of the electro-acoustical transformation and the frequency band covered. As regards design, there is a definite relationship between these two parameters, and an investigation into the possibility of raising the receiver response for a given band is described. Since the diaphragm is subjected to a constant force of attraction, the response limit will be reached when the diaphragm can just be guaranteed not to stick to the magnet poles. Owing to magnetic saturation, however, the response in practice cannot be raised to the theoretical limit. If q is the response and xi a variable associated with the magnetic properties of the material and its structure, then deltaq/deltax1 = 0, where delta2q/delta xi2 0, represents the condition which should be satisfied and forms the basis of design. Electro-acoustical transformation of magnetic materials, when magnetic saturation is taken into account, is also discussed.