"S.B." could be an American abbreviation for "Saengerbund" (Sängerbund) which was/is a singing group (using the German language) that was very common throughout the US in small and large towns up to ~1915. We have an active "Saengerbund" here in Washington DC and just heard them perform last fall (singing German & Swiss folk songs and "Lieder" (songs) of Schubert, Beethoven, et al.). A singing group of just men would usually be called a "Maennerchor" (Männerchor). Bob in Germantown MD