Table of Contents


20-Note Cobs

32-Note Cobs

*32-Note Cob Diagram:

Alphabetic List

Numeric List

Tuning Scales

Roller Organs were not tuned to standard pitch, so there is great variation. A scale beginning on D will allow D, G, A, C, and E major chords and D, G, and A scales, so it is well-suited to play in the key of D or G. The mean temperament tuning1) allows it to play in almost perfect harmony.

1) Mean temperament was used prior to 1908 (approximately). At that time the Autophone Company switched to equal temperament because the reed sets were slightly less expensive.
2) most Gems after 1888, some Concerts after 1908
3) most Concerts before 1908
4) some Gems after 1908, some Concerts after 1908
5) most Gems before 1888