[ Ref. Bill Koenigsberg in 200727 MMDigest ]

I find the spill valve of the Duo-Art "fan system" expression unit
most interesting.  It is pneumatically operated, and each "step" is
individually adjustable.

It is operable from either Theme or Accompaniment or both.  All of it
can be operated from the Accomp side, changing any coding for Theme.
Or also level A-16, operated by power 8 Accomp, can be changed to be
operated by Theme 16 only, thus giving the "Crash" different top
values depending on whether or not level A-16 is on or off.

The whole spill can be operated by the Theme, giving different values
for the Accomp, particularly at higher settings.  This seems to give
the overall playing volume the possibility of being "fitted" to the
room.

I have a Steinway "D" (9-1/2-feet long) and I appreciate being able
to change the curves and to have the volume as I have preset it for
my room.  Pianos with automatic crescendos are susceptible to volume
alterations due to differing playing Tempos, whether intended or not.
One need only to drop or raise the Tempo on a Frank Milne Medley roll
to hear the effect.  I grew up with an Ampico, which did it.

I have a half dozen or so "fan systems" in my shop and they have
several slightly different internal lay-outs.  Some are the "long
end on-end" Theme-Accomp style.  Three systems are the same square
shape as earlier Duo-Art expression units, but with fan accordions
and a completely redesigned interior and the very adjustable vacuum
operated spill.

I have a long system operating a small grand piano, and the big square
ones are operating a 7'6" Steinway and the 9'6" Steinway.  Both of the
latter are really good pianos, so I dare believe they play as Aeolian
intended in my 20- by 40-foot living room.  I also think they could be
set up to dominate a concert stage -- and run me out of my house!

Geoffrey Kaiser [a.k.a. Tockhwockh]

 [ A photo of an above-keyboard "drawer" model fan system is at
 [ https://www.mmdigest.com/Tech/DuoArt/grimes_fan1.html 
 [ MMD articles about the Duo-Art fan accordion system are indexed
 [ at https://www.mmdigest.com/archives/KWIC/F/fan-accordion.html 
 [ and https://www.mmdigest.com/archives/KWIC/F/fan.html  -- Robbie