Turntables, Arms & Cartridges

Skyanalog is not alone in specifying a high-purity square iron former at the heart of its MC generator – so too do Hana [HFN Dec ’20], Charisma Audio [HFN Feb ’15] and Lyra [HFN Feb ’23]. It’s possible to see this (light grey) square component, overwound with fine copper wire, under the clear plastic cover that protects the magnet’s (gold coloured) poleshoe and yoke [see below]. The higher the permeability of the material chosen for the former, and the coil/former inductance, the higher will be the achievable output voltage as the coils cut the flux lines between the magnet polepiece and yoke.

For the designer this must be judged against the weight – the ‘moving mass’ – that results at the far end of the cantilever. Low mass benefits responsiveness and frequency response but reduced coil turns and thin or lightweight alloy formers will limit the cartridge’s output potential. Cartridge builders must also choose the ideal shape for this former, with square plates and cross-shaped armatures being most popular. Ortofon often uses the latter, for example. Depending on how the magnetic circuit is arranged, one shape or the other will offer the optimum profile to cut the lines of flux. PM