As I recall this thread started with a question dealing with
initial set-up of the Ampico A after major repair or restoration.
Of course most owners want to go a step further and extract the
best possible performance from their Ampico. But for the sake of
a fair discussion, let's assume that most responses really deal
with initial set-up.
To my knowledge, Larry Givens was first to publish information
about Ampico regulation in the post production, collecting era. In
his 1963 book, he outlines the physical position of the expression
valve and the two components acting on it. With the expression valve
seated, the top moving board is set parallel to the board which holds
the three expression pneumatics. The shaft collar on the expression
valve shaft is set 3/16-inch below the metal bushing. The spring
pneumatic is set 7/8-inch open, inside measurement.
From here, one needs to set the pump spill with the amplifier
deactivated. Usually this is followed with finding the minimum
intensity at which all notes sound softly and evenly. Adjusting the
minimum intensity is by the screw on each crescendo. Finally, the
maximum vacuum is set by adjusting the amplifier stop screw.
At this point, fine regulation begins. MMD readers have already seen
several different techniques surface. My offering at this point is
just one small tidbit as it would take pages for me to describe my
There is some latitude in setting the pump spill valve. Most
literature gives 20 inches vacuum as the desired setting (amplifier
off). Consider reducing the setting to 17-18 inches. Doing so will
make all rolls sound somewhat more mellow, but B coded rolls will sound
much nicer. There is a reason for that, but I will not go into it
The upcoming issue of the AMICA Bulletin contains my article which
discusses the A system characteristics. Graphs are displayed showing
in detail those traits. It is actual data, and not theory. To my
knowledge, no one has ever displayed or fully discussed this material.
It will be an "eye opener" to many Ampico collectors.