videos in AudioSet
A list of about a million ten-second YouTube clips, each labelled with the sounds in it, that Google published in 2017. Labs use it to train and test general audio and music models.
Including Mandolin Serenade - Sérénade de Mandolines - Classical Mandolin Solo, Our Time / Classical Guitar Solo (Maria Linnemann) - New York 2009, It's going to rain - Mandolin Boogie