PURPOSE: To obtain extremely good sound quality from low to high tone ranges by using a magnet cont. 33 to 47 atomic % platinum and consisting of the balance iron.

CONSTITUTION: An alloy cont. 33 to 47 atomic % platinum and consisting of the balance iron and more preferably an alloy contg. 37.5 to 42.0 atomic % platinum and consisting of the balance iron are used for the audio cartridge. An iron alloy which contains 35 to 47 atomic % platinum and 0.1 to 10 atomic % ≥1 kinds among Ti, Mo, Nb, Ta, W, Cr, V, etc., and is known as platinum magnet is otherwise used. This magnet has the high performance of 10 to 11 kilogauss residual magnetic flux density and 4.5 to 5.5 kilooersted coercive force and has extremely high corrosion resistance. The surface discoloration is not generated at all. There is no glittering in the sound quality from the low to high tones and particularly the clearness of the high tones is magnificent.