Solo section. In an orchestrion, organ, or other instrument a chromatically-tuned (usually) extra instrument (such as a rank of pipes, set of xylophone bars, or bells) which, on occasion, plays the main theme or solo part while the other sections of the instrument play accompaniment. In a fairground organ, a brightly-voiced rank of pipes may play a solo part while other pipes in other sections of the organ provide accompaniment and countermelodies.
MBSI
Musical Box Society International