When the music industry changed in the mid 30's (better recording studios, radio, louder music, Big Band era.... ) the soprano sax didn't fit in. The big band saxsection sat the standard, alto-baritone. And the bandleaders were often piano men. The american big band leader Charlie Barnet played soprano saxes. I think the C soprnos were not so poular as the C tenor/melody. I have a Buescher C soprano and according to a letter from Vincent Bach International (Selmer US export division back in the 80's) Buescher just made around 500 c sopranos.The soprano went "out of fashion" for a long while as a popular instrument although still made by a few companies in the late 1930s to 1965 period. In the 1920s to early 30s it was very popular with lots of C sops besides the Bb.