The discussion about the restriction found attached to the secondary
valve in the Ampico A system is a bit of a mystery.  From my own
experience, I have _always_ found these restrictions installed on _all_
Mason & Hamlin Ampico A systems.

The restrictions come in two styles.  One is as previously described:
a belly cloth material force fit into the top valve seat.  The other
style is a packing felt punching with a center hole that is fitted with
a rubber tube.  The rubber tube is flush both sides with the punching.

There are only two possible reasons for these additions to the top
valve seat.  One is for restricting the flow as the valve returns to
rest.  The other is to muffle the valve noise.

It is my opinion that, contrary to the heading of this discussion,
the only purpose of these additions, is to make the valve operation
quieter.  All Ampico A systems with the right side up secondary valves
have some form of muffling on the valves.  It is usually a strip of
cloth that covers the entire length of each full deck of secondary
valves.

With the Mason & Hamlin, one always finds an upgrade in the Ampico
installation.  Each valve with its own muffler is part of the upgrade
given this high quality product.  Additionally, one finds the drawer
sides fitted with piano case matching veneers.  Wooden conduits cover
the electrical wiring, and the tubing layout is very well organized.

Other examples of valve muffling are found in all Ampicos.  The loud
and soft pedal valves are covered with felt mufflers.  If my memory
serves me, I think I have found secondary valve mufflers on some Knabe
pianos, too.

Bob Taylor
http://members.socket.net/~rtaylor/aeolian_pipe_organ.html