Never Heard of This

[tannoy man]

http://www.ebay.co.uk/itm/VINTAGE-MOVING-MAGNET-SPEAKER-ORMOND-/120920958428?pt=UK_Collectables_RadioTelevision_Te lephony_SM&hash=item1c277365dc#ht_852wt_989

[BTH K10A]

Early cone loudspeakers were of the moving magnet principle (I think Siemens developed the principle) but were superceded by the moving coil types we see today

1924, two General Electric researchers, Chester W. Rice and Edward Washburn Kellogg patented the modern, moving coil, direct radiator, loudspeaker, based on a prototype Rice had constructed aound 1921, which become the prominent design for all loudspeakers. In 1925 a research paper written by Chester Rice and Edward Kellogg at General Electric established the basic principle of the direct-radiator loudspeaker with a small coil-driven mass-controlled diaphragm in a baffle with a broad midfrequency range of uniform response. Rice and Kellogg loudspeakers were sold to consumers under the name of "Radiola'' loudspeakers beginning in 1926, and were superior to anything previously invented by lowering sound distortion and raising audio quality for the consumer.

In the UK, BTH adopted the "Rice Kellog" principle very early on and probably produced the first british Hi Fi loudspeaker.

[tannoy man]

Comprehensive. Thanks:)