Era
Only one headphone here goes back this far, and it's an important one. Beyerdynamic launched the DT 48 in Berlin in 1937 and kept it in production until the end of 2012, so the pair you find will almost always be much younger than the design. Headphones like this were tools for broadcasting, measurement and hearing tests rather than music at home, and the catalogs sold them by impedance and plug. Check which impedance and plug a listing has, since both changed over the decades.
1 model we cover.