Regarding the Ampico with the 1"x1" pneumatics.  Dr. Hickman found that
when the sustain pedal is on, a player piano plays louder than it does
when the sustain is off.  I think we can understand this by observing
that when the pedal is on, all the strings are resonating freely.  When
the pedal is off, only those notes that are playing are resonating.

Dr. Hickman thought that the Ampico should give a boost to the system
when the pedal was on so that the piano would play louder.  Those little
pneumatics are connected to the loud pedal valve or teed to the loud
pedal supply hose such that as suction is applied to the loud pedal, it
is also applied to the little pneumatics.  The system plays a little
louder.

I have wondered whether this really necessary.  A piano naturally plays
louder with the pedal on, why increase it?

Jeff Davis
in sunny Seattle, WA