Hello:  My name is Bob Garner.  I am new to this group but have been
interested in mechanical instruments for quite a few years.  I live
in Jackson, Mississippi, and the number of instruments in this area
is very limited.

I read an article several years ago that stated the Ampico A slow and
fast crescendo times changed somewhere during the production from 11
seconds and 2 seconds to 9 seconds and 1 second.  During the years that
have passed since I read that I have only seen technical information to
support the 11 second and 2 second durations.  This is in the 1919
Ampico manual with the 1920 supplement.  As the years went by I forgot
about the 9 second and 1 second durations that I had read about many
years ago.

Recently I was surfing the net and came across an article by Craig
Brougher, Re: Ampico Crescendo, and in this article he states that the
later model Ampico had a crescendo of 9 sec slow and 1.5 to 2 sec fast.
Could someone in this group please let me know where/what the
documentation for this information is and what year these speeds were
first used?

Thank you,

Bob Garner
tippyg@aol.com.geentroep [delete ".geentroep" to reply]

 [ Documentation of the Ampico B system, which was designed especially
 [ for compatibility with earlier "A" rolls, is presented at the MMD
 [ Tech pages, http://mmd.foxtail.com/Tech/Ampico/index.html
 [
 [ Contemporary emulators for MIDI file renditions of Ampico rolls
 [ generally implement the crescendo rates implied in the Ampico B
 [ 1929 service manual: the slow crescendo rate is 6 decibels in
 [ 4 seconds and the fast crescendo rate is 6 decibels in one-half
 [ second.  6 decibels sound increase results when the hammer velocity
 [ is doubled.  The relation of hammer velocity to action stack suction
 [ is non-linear and is greatly affected by the friction in the piano
 [ action.
 [
 [ The Ampico B slow and fast crescendo rates are consistent with
 [ your recollection of slow and fast crescendo durations.  (The rates
 [ of the earlier Stoddard Ampico system were a bit less.)  See also
 [ the technical paper about the spark chronograph, reproduced at
 [ http://mmd.foxtail.com/Tech/Ampico/jasa.html
 [
 [ -- Robbie