A soft diapason-like pipe organ stop.
duplex comb(s)
In a disc music box, two identical combs that are played by the same set of star wheels, in which two points on one star wheel pluck the teeth on two combs at once. (In contrast to double combs, also listed in this Glossary.)
duplex roll mechanism
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.
edge drive
The type of drive used to power musical box discs. In the gear type the toothed edge of the metal disc meshes with a toothed drive gear. In the sprocket type a toothed or knobbed sprocket wheel mounted under the disc near its outer rim engages with corresponding slots or holes in the outer edge of the disc.
electric lighting effects
See lighting effects.