Realizing that the audience for this posting will be quite limited,
I will try not to bore the rest of you too much.  My fascination of
roll coding now includes the Aeolian Duo-Art Pipe Organ roll, also
known as the 176-note roll.  Since there is no one to talk to about
how "the factory did it", we are left to discover on our own.

One of my goals is to capture the data on these rolls and to create
MIDI files.  There are listed in various catalogs, 539 titles available
for the Duo-Art roll.  Once I have all of them in MIDI format, I will
no longer have to worry about torn paper and other paper issues.

Secondary to this transcribing effort, is the ability to "see" how
the factory used the resources available in the Duo-Art system by
"searching" the files.

In various reference works, the tracker scales of many instruments are
available.  Common in many of these scales are unknown uses of various
tracker holes.  The Aeolian Duo-Art organ roll is no exception.  Those
of you who are also interested in the meaning of "L. C. W" assigned to
several tracker holes, don't hold your breath because I still don't
know.  But, as I study the rolls so far, I am able to conclude several
things about coding.  Ultimately, when all 539 rolls are recorded,
I can tally how times a certain hole function is used, and thus rank
its importance.  Some holes may never be used.

Depending on which reference work is used, "L. C. W." may be found on
tracker hole #171.  Also, this hole is listed as Echo Coupler.  I can
say that the hole #171 is used to couple the "echo" to the "great" or
lower manual.  So far, I have found only one roll that couples the echo
to the great.

The "jackbox" is the control center for changing holes in rolls to
electrical outputs for stops, swell shutters, and various couplers.
Corresponding to each control hole in the roll is a toggle switch or
a "jack" switch.  The hole causes the switch to move, first to on, and
the next occurrence will cause the switch to then move off.  A few
control holes bypass the jackbox. but most operate this way.

Each of the jack switches has a wiring post array with the minimum
number of wiring posts being two.  Many of them have four posts.  The
jacks that correspond to the Echo couplers have the most with eight
wiring posts.  From this, one concludes that Aeolian wanted the jack
assigned to echo operation to have multiple output capability.  Some
of the possibilities are turning on multiple echo stops, coupling the
echo shutters to shutters for great or swell, and of course coupling
the echo to the appropriate manual.  My web site shows the completed
jackbox wiring posts.

At this point in my research, I have already concluded that Aeolian was
letting the Duo-Art scheme evolve.  Where the early efforts followed
closely the scheme used in non-automatic 116-note rolls, soon the
Duo-Art roll abandoned those constraints.

As an example, the 116-note roll players have a lever that selects
which row of holes in the two row tracker bar activates the two
keyboards.  That scheme is also found in early Duo-Art rolls, but later
consoles abandon that control lever.  After all, the same result can be
accomplished by just changing the perforations and eliminating all that
switching.

Backing up this conclusion is the fact very early production rolls are
issued in the newer format in later years -- the same roll exists in
two formats.  If you think Ampico A and B compatibility issues are bad,
just play the old version of one of these rolls on a newer Duo-Art
installation: where the roll goes into the "Unison" section for maximum
volume, the newer organ will fall totally silent in the Swell division!

The involvement of pedal notes which share the same holes used for the
manuals brings up a whole chapter of discussion, which I'll omit.  But
the Duo-Art pedal assignment hole, #176, is much more complex than what
meets the eye.

My last morsel is the fact that early Duo-Art rolls have printed
instructions throughout, just like the earlier 116-note roll.  Rolls
in which the echo is used have the instructions at the beginning,
"Prepare Echo", and then list the stops to be drawn.  Obviously, the
roll couldn't turn on the stops.  But what about later, when the rolls
were loaded in a closed cabinet Concertola?  (And maybe with no printed
instructions on the roll.)  Who draws the Echo stops then?

These are all very weighty issues.

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