In 1893, Heinrich August Knopf started a Brass Workshop in Markneukirchen to manufacture French Horns.
His oldest son Herbert Fritz started his own independent workshop in 1919, wich still exists and produces French Horns today.
Younger son Kurt took over August Knopf in 1926 and was succeeded by his son Edgar until retirement in 1997, after wich the firm closed.

https://www.knopf-horn.de/e_index.htm