Pickup cartridge, moving-coil  --  A pair of tiny coils are mounted so that they can rock about an axis between the pole pieces of a magnet. Each responds only to one plane of stylus movement. To minimize mass, the coils have few turns and so are low impedance and give low output; they thus need special pre-amps or transformers. Some have been produced using many turns of very fine wire, thereby giving higher impedance and output.