2-Way Volume Control Switch
and Expression (1921-1926)

(Photograph courtesy of Art Reblitz)

Knob and label used with 2-way (loud and soft) expression system from 1921 through 1926. The same type of knob was also used in the later 3-way system, with a different label. Variations include plain brass or nickel plating on either the knob, the label, or both, and several patterns of knurling on the rim. (Seeburg G #94,919, made in 1921.)

(Photograph courtesy of Art Reblitz)

The paddle-type switch used with the late style knob in the 2-way expression system. The back end of the shaft for the knob is shaped like a little crank, and fits between the two pins. When the switch is set on “soft”, a channel connects atmosphere to the soft mechanism, keeping it on soft. When set on “loud”, the channel is closed, allowing the soft mechanism to work automatically from the music roll. (Early KT Special #159,898, made in 1924.)

(Photograph courtesy of Art Reblitz)

A double switch mechanism for xylophone on-off, and drums on-off in early KT Special 159,898, made in 1924.

(Photograph courtesy of Art Reblitz)

The automatic expression mechanism for the 2-way switch is mounted on the vacuum distribution box. The spring-loaded vacuum regulator (toward the right side this picture) faces the front of the piano, and is adjustable for the soft expression level. The two smaller pneumatics always face the left. The upper one operates a bypass around the expression regulator for loud playing, and is controlled by the music roll. The lower one operates the action cutoff during rewind. This example is from KT Special 159,898, made in 1924, and has the large vacuum reservoir mounted in back, with the open end facing up. Other styles often have the reservoir mounted on the right side (opposite the two smaller pneumatics), with the open end facing down.