I am planning to make a pedal-electric Duo-Art Vorsetzer, and I have
available an original and full upright mechanism, which has the late
2-tier round valve plate stack with 1-inch by 4-1/2-inch pneumatics.

I note that generally Ampico used 1-3/8-inch by 4-inch pneumatics, and
an early British Aeolian upright graduated pneumatic stack goes from a
massive 1-1/2 inches by 5-1/4 inches in the bass down to 1-1/2 inches
by 3-3/4 inches in the treble.

As I want to use the Vorsetzer on a Concert Grand at times, do I need,
or would it be ideal, to have a stack with larger width pneumatics than
1 inch by 4-1/2 inches?

Ian McDonald