sound check
- https://www.dead.net/archives/1973/photos/way-sound-checka
- https://www.dead.net/archives/1974/photos/jerry-sound-check
- https://www.dead.net/archives/1974/photos/billy-sound-check
- https://www.dead.net/archives/1974/photos/bobby-phil-sound-check
- https://www.dead.net/archives/1978/photos/mickey-hart-campus-stadium
