I’ve received a very old pair of mono bakelite headphones that I would like to re-use for demonstration purposes. Just for voice audio and morse code tones.
The writings on the side of each headphone:
SB & CO C.L.R. 1939
This leads me to believe it’s a C-type unit (whatever that means) with Low Resistance (Impedance) from the year 1939. The DC resistance I measured is around 62 Ohms for each headphone and there are no shorts or open circuits. The two earpieces are connected in series and each earpiece has two coils below a thin metal disc.
Image 1: inside closeup of headphone coils (disc removed)
Image 2: wiring
What would be the ideal or maximum signal levels can I drive these headphones with, and what sort of pre-amplifier would I need to make these headphones produce the best possible (probably still awful) sound when driven from a laptop or radio's headphone socket?
Is this where I need to dig up and replicate an old, valve radio's audio output stage? I am hoping to do this with slightly more modern components..