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MMD > Archives > September 2015 > 2015.09.24 > 07Prev  Next

Mystery of the Missing Ampico Intensity
By Mike Walter

Hi all,  The Mystery of the Missing Ampico Intensity is no mystery at
all!  John Grant goes to great lengths to explain his philosophy about
the Ampico systems and throws in some info about the Duo-Art system and
the Welte system as well.

The information that is printed in the service manuals are guides to
help the repair person in his quest to get a rebuilt instrument to
sound as good as it sounded when it was new.

Art Reblitz and David Saul in their restoration guides give a wonderful
and thorough process for the restoration of an instrument and they
should be followed to the letter for the best results.

Although the Ampico A and Ampico B systems have different functioning
systems, they do both share many similarities.  When a test roll is
placed in an "A" drawer, the Ampico switch should be turned on.  Each
note should play quietly.  This will probably be less exact because
of hammer weight and amount of felt on the hammer as each note is
played up the scale.

To help compensate for this problem, the stack is divided into two
sections, bass and treble.  Each section has a crescendo unit, and on
the crescendo unit is a fairly large spring which can be tightened or
loosened to raise or lower the vacuum level to that section, so that
the softest playing in that section can be obtained.

On many Ampico A rolls there are individual or two notes played
together without any intensities activated.  These notes play very
quietly.  This is the base level for the Ampico A system.  By
introducing the first intensity, the vacuum level is raised, giving
a louder sounding note.

The Ampico "B" system is much different in format, although the results
are fairly similar.  There are two test rolls which are used to regulate
the B system.  The large main roll tests all of the various sub-systems
in the piano.  When the note repetition test appears, the First
Intensity Adjuster (a five position "bleed") is placed in a position
where all first played notes will play quietly and the second note will
play a bit more loudly.

The second test roll is a Note Compensation Test Roll.  The
instructions on the roll direct the user to activate the "0" T and also
the hammer rail lift by pulling the control tubes off of these devices.
Now the process can be started by listening to the loudness of each
note played in comparison to the other notes being played in that

The poppet rods connecting the striker pneumatic to the back of the
piano action have a section of the rod by the pneumatic that is
threaded.  If a note plays too loudly, compared to the other notes
being played in that section, the rod can be turned counter clock-wise
and the threading will shorten the opening of the pneumatic, thereby
reducing its force, and softening the striking blow to the strings of
that note.  If the note sounding is too soft, the opposite approach is
taken and the opening of the pneumatic is increased, thus increasing
the blow by the hammer on the strings.

The "B" system does, verily, have a first intensity that is used quite
often.  There are also two additional devices for softening notes being
played.  These are the hammer rail lift, which is used for softening
certain passages, as the artist probably played them, and the 0T hole,
which reduces, usually, individual notes by perhaps 1/2" of vacuum.

Bob Taylor, a great and knowledgeable Ampico expert, would probably
give a greater and more thorough explanation to both systems.  But,
there is a "first intensity and" it is used very often.

Best wishes,
Mike Walter

(Message sent Thu 24 Sep 2015, 23:32:30 GMT, from time zone GMT-0700.)

Key Words in Subject:  Ampico, Intensity, Missing, Mystery

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