This paper describes the influence of changing similarly the size of magnetic circuit of electromagnetic transducer upon its force factor, inductance of voice coil and negative stiffness , etc. . This principle is helpful not only for the experiment using similar magnetic circuits of different sizes, but also for the design of transducers. Applying this for designing the electromagnetic receiver, we find that the smaller magnetic circuit, or the smaller receiver is the better for increasing specific response, and also that it is preferable that effective mass of armature should not be greater than that of diaphragm.
