![](https://coimages.sciencemuseumgroup.org.uk/37/647/large_thumbnail_1927_0113__0003_.jpg)
Primax moving iron loudspeaker, 1924-1927
1924-1927
1924-1927
1980
1970-1985
1940
1927-1930
1938
1935-1940
1935-02-22
25 June 1934
25 June 1934
1971
1970-1985
25 June 1934
1968
25 June 1934
1950-1970
1960-1970
1960-1970
1960-1975
1940-1970
1960-1980
1970-1985
1980-1985
1986
circa 1955
1932
1932
1980-1985
1950-1970
1950-1970
1945-1960