The American Magasine "The Minstrel Tempo" for January 1901 cvarries an advertisment for "Sonoro" guitars, mandolins,and banjos made by Chas F Alberts 205 S 9th Street, Philadelphia. Pa.
Apart from a later reference to Alberts beinmg "Phila's Old Reliable Violin House" we know no more.
Chas F Alberts
Do you have a banjo by this maker? can you supply us some images?