BTH Amplified MC Loudspeaker, 1927

door John Koster

BTH brengt vanaf 1926 elektrodynamische luidsprekers op de markt. Dit type uit 1927 heeft een diameter van circa 6 inch en is voorzien van een ingebouwde versterker en voeding.

Since 1926 BTH manufacures the moving coil loudspeaker. For use with either AC or DC, the unit incorporates the output amplifier as well as the mains equipment giving the necessary high anode voltage, exceeding 400, while the grid bias is also obtained from the mains. The electro-magnet is of large diameter, the pole being about 1 5/8 inch across. A supple centring device holds the coil in position, and the diaphragm is about 6 inch in diameter. Plunger operated contacts break all current supply circuits by the act of removing the unit from its containing cabinet