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Phono Cartridges Explained: How They Work

Phono Cartridges Explained: How They Work

Have you ever wondered what is the difference between a MM and MC phono cartridge? In this Expert Advice, we will explain how they work and why you should choose one or the other.

Moving Magnet Cartridge

The cantilever of a moving magnet (MM) cartridge is fitted with a pair of small permanent magnets, positioned at the opposite end to the diamond and placed between two sets of stationary coils. The magnets + coils assembly constitutes a miniature current generator. When the magnets oscillate under the effect of the vibrations transmitted by the stylus through the cantilever, they induce a tiny electric current in the coils.The main advantage of moving magnet cartridges is their high output level (between 2 and 5 mV).

Moving Coil Cartridge

On a moving coil (MC) cartridge, it is the two coils that are attached to the upper end of the cantilever. They move in the air gap of a fixed permanent magnet according to the oscillations of the stylus. These coils are much smaller than on a moving magnet cartridge. They are made with a very thin cable, which has a direct impact on the output level and the impedance, which are lower than on a cartridge with moving magnets. The lightness of the assembly offers finer and more precise tracking. The result is a wider frequency response and a more detailed sound reproduction.

Moving Iron Cartridge

A Moving Iron (MI) cartridge works very similarly to a moving magnet design, except that the magnet is replaced with a magnetic alloy. This has the advantage of lighter and more precise moving parts. This technology is found mainly with Grado phono cartridges. Moving Iron cartridges have a relatively high output making them compatible with the MM phono input found on most integrated amplifiers.