Questions about the piano stop

[ChristopherDB113]

I know that theatre organs usually have one or multiple (depending on the size of the room) pianos connected to them and there is a stop which activates them. However, I wanted to know how the volume was controlled since an organ manual is usually not velocity sensitive, and how the sustain pedal was connected (perhaps a dedicated expression pedal for that).

[toodles]

In a theatre installation, the piano would probably have been located inside a swell chamber, so expression would have been accomplished just like for the pipes. Of course, this doesn't provide touch sensitivity, but that's how it is with pipe keyboards.

If sustain control was provided, it could be through a kickswitch or a toe stud.

[AllenAnalog]

Some installations had control of the vacuum level on the note pneumatics in steps. I believe the piano in the Wanamaker organ has that.

Not a theater organ, but my Steinway Duo-Art reproducing piano was once part of a player pipe organ in a residence. It has 16 levels of expression, modulating the vacuum with a 4-bit binary code. A kick switch on one of the expression pedals controlled the sustain. (That type of control can also used for the dampers on a set of tubular chimes.)