ACOUSTIC GUITAR STRING SET String Sets Acoustic Guitar EJ Bronze 80/20 Extra Light Series (010 - 014 - 023 - 030 - 039 - 047). Bronze 80/20, commonly known as brass, is the original alloy of paraacoustic strings selected by John D'Addario Sr. and John D'Angelico in the 1930s. Bronze 80/20 strings are very popular for the recording due to its sharp, deep and projected tone, and appealing to many traditionalists and vintage enthusiasts for its historical significance.