Roll frame or spoolbox assembly in an electric piano, photoplayer, or orchestrion which accommodates two rolls, so that one roll can play while the other is rewinding or at rest. Made by Hupfeld, Seeburg (for photoplayers), Wurlitzer (photoplayers and band organs), and others. Also, duplex roll changer: two revolver mechanisms or automatic roll changers (also listed in this Glossary) arranged side by side, with several rolls on each changer mechanism. These were made by Hupfeld and Philipps.
MBSI
Musical Box Society International