When I looked at this question which was asked recently about identifying a Marvel superhero's logo, the first thing that I noticed was the fact the A logo was circled, which I suddenly felt was specific to the Marvel Cinematic Universe.
Out of curiosity, I tried checking if the Avengers had a logo of any kind before that, or if all they had was a stylised "Avengers" on the comics cover.
To my disappointment, my searches so far have been moot, because I keep finding images of the Marvel Cinematic Universe's movies title. The only thing I was able to find was that the original "Avengers" stylised title was created by the designer Gasper Saladino in 1972:
Has the Avengers' title and logo changed throughout the years?