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 Quick Tip: How to Tune Kicks and Percussion to the Key of Your Song, Structure and Arrangement in Electronic Music: Creation (Further Processing), Layering in Electronic Music: Synths (Supersaw Punch)