Public

Public
 

there was few public at the concert or there was a small public at the concert?

There were a few present. (Here, 'few' is a noun, and it takes a plural verb.) (When 'few' is used as an adjective, it modifies a plural noun.)

There was a small public. (The noun 'public' isn't used much. I'd use 'a small group of fans', 'a small fan base,' or 'a small gathering of fans/followers/enthusiasts.')