The musical is required to have live orchestra, which usually consists of these instruments and conductor. For each instrument there is a link either to video with examples how it sounds or to wikipedia.
2 keyboards (stage piano)
2 guitars
5-6 violins
2 violas
2 cellos
Oboe / english horn
2 horns
2 trumpets
2 trombones (posaune)
saxophone
harp (only in Wien?)
drums