An electromagnetic transducer such as an audio speaker which includes an asymmetric diaphragm to deliver smooth frequency response with reduced distortion by reduction of common modes in the diaphragm. The rotary drill bit may include a bit body, a cutting pocket defined in the bit body, and a cutting element rotatably coupled to the bit body. A resistor RF connected between the emitter of said second transistor and the base of said first transistor provides a voltage controlled current feedback from the amplifier output to its input. A second uncured composite layer is assembled on the bond jig over the upper outer surface of the hollow mandrel and at least a portion of the first uncured composite layer, the second uncured composite layer having at least one uncured resin-impregnated layer. 3X and which is selected from a group consisting of LiNiO2, Li2NiO2, LiNi2O4, Li2Ni2O4 and LiNi1xMxO2, whereby it is possible to obtain a nonaqueous electrolyte solution secondary battery which is superior in battery properties, especially charge and discharge cycle properties, retention properties and safety. According to the invention, intensity values of the light of a flame of the combustion chamber are recorded for this purpose via the optical system, and the front lens surface is cleaned if necessary.