Show the iPod generation what nickelodeons were before there was cable TV. Then let them marvel at the ghostly way player pianos pound out Gershwin or a theater organ pulsates with the heart-pumping pace of a movie climax. Renovated barns house an assortment of elaborate automated instruments from the 1870s to the 1930s. Ongoing tours and demonstrations last about 90s minutes and explain how the intricate instruments work. It’s a fresh way to teach a lively dose of American music history.