[MrFixr55]

+1, 462 Ron.

I am not sure when AlNiCo was invented, but I think it was likely perfected for WWII. The only pre-WWII PM dynamic speakers that I have ever run into were in battery powered sets and in earlier sets like my 1935 / 36 RCA 5BT and 6BT and Coronado 650 Farm Sets, these magnets were pretty big. I have twin 1933 4 tube lunchboxes, an RCA R-17M and GE BX (Actually the same radio, RCA Made GE and Westinghouse radios from 1930 - 1935. GE and Westinghouse made RCA Radios from 1922 till 1930 till RCA bought Victor Talking Machine who had just starting manufacturing radios), and for a little 5" speaker, the magnet is quite large. The horseshoe magnet in my Radiola 100A magnetic speaker is similar to the type used in the generator of the old hand crank telephones prior to central station phone systems.