Grado Gold, like most Grado cartridges, is a Moving Iron design.
From Michael Fremer's Stereophile review of Soundsmith SMMC1 moving-iron phono cartridge:
From Michael Fremer's Stereophile review of Soundsmith SMMC1 moving-iron phono cartridge:
In a typical moving-magnet (MM) cartridge, a tiny permanent magnet, attached to the cantilever and positioned between two sets of fixed coils inside the body of the cartridge, induces a tiny current in the coils when it is vibrated by the stylus's motions as it navigates the record groove. In a moving-coil (MC) cartridge, the magnet is fixed; it is the coils attached to the cantilever that move. The mechanical and electrical advantages and disadvantages of both designs are best discussed elsewhere.
Moving-iron designs such as the SMMC1, or the Grados, use stationary coils and magnets and a small piece of "moving iron." In the original B&O design, what moves is a cross-shaped piece of ultra-low-mass, high-purity iron attached to a soft elastomer damper stabilized in a plastic frame. The iron also incorporates a minuscule tube into which the cantilever is inserted. Each arm of the iron cross is associated with a fixed-coil/magnet structure and as the cantilever moves, it varies the distances between the four arms of the iron cross and the four fixed-coil/magnets, thus inducing tiny voltages within the coils. The advantages of this arrangement include ultra-low moving mass, even compared to an MC design; relatively high output (because the stationary magnet/coil structure can be made large); high suspension compliance; and low vertical tracking force (VTF).