RC equalizer - frequency response equalisation for moving magnet cartridges

RC equalizer elektor april 1983 frequency response equalisation for moving magnet cartridges RC equalizer Moving-magnet cartridges must be terminated with the proper impedance in order to achieve optimum sound. This article attempts to clarify the electro-acoustic factors involved and presents a simple and inexpensive method of obtaining a great improvement in sound response. Cause and effect The causes of the differences in sound can be found in the construction of a moving magnet system, and are explained by the equivalent circuit of this type of pick-up in figure 1. The stylus is connected to a small permanent magnet. Coils are arranged in its magnetic field and the field variations caused by stylus movement are converted to a varying voltage by these coils. This type of coil has many turns. Since there is very little space in the cartridge, the wire used for the windings is very thin. In addition to the coil inductance (L: 200 mH . 1 H), this leads to a considerable internal r...