Very rare & old professional studio collector microphone made in holland art deco period, manufactured from 1925 to 1935 *** philips type 4043 *** suspended hexagonal model (missing suspensions) with carbon granule capsules. Black lacquered solid cast iron body. This is a carbon microphone of the type invented by thomas alva edison in 1878, used first in telephones and then in early radio studios throughout the 1920s. The microphone capsule (or transducer), filled with carbon grains, is subjected to a constant electrical voltage. A metal diaphragm positioned in contact with the grains is free to vibrate. Sound waves (e.g. The speaker's voice) cause the diaphragm to vibrate, causing the pressure on the carbon grains to vary proportionally. In this way, thanks to the physicochemical properties of the coal granules, the electrical resistance undergoes a variation and the circuit is traversed by a variable current which reproduces the tendency of the sound wave which generated the pressure. This signal, after being sufficiently amplified, was used to modulate a high-frequency radio carrier in early broadcast stations. The microphone can be placed on a table or floor stand. Device in excellent aesthetic condition ideal for collectors of old microphones a great gift idea to give or treat yourself dimensions - 14 X 14 cm net weight - 2, 550 kg.