[ Ref. 130406 MMDigest, "Aeolian 116-note Pipe Organ Rolls" ]

Upgrading the 116-note roll

I would not say the process is difficult, it is just tedious and
requires a great deal of patience.  Also, a thorough understanding
of how the Duo-Art pipe organ roll (176 note) controls all organ
functions is necessary.  Reviewing that system first will help
understanding of this posting.

Like most players, the Duo-Art organ roll reader uses vacuum to read
the paper roll.  A pouch rises when a note hole opens, but it makes an
electric contact rather than moving a valve.  The electric signal then
activates the organ just as the keys would.  Stops and other controls
are activated in a similar manner, but often a stop is on for an entire
roll.  If several perforations were the length of the entire roll,
paper structure problems would make the roll fail in a short period
of time.

Aeolian solved the problem of super long perforations by a set of
toggle switches that control the stops.  It only takes a brief
perforation to move the switch.  The switch remains on until another
brief perforation occurs, then it turns off.  A box that contains all
these toggle switches, over fifty of them, is called a "jack box".
Adding code to the 116-note roll is adding the inputs necessary to
control this jack box.

It seems simple enough.  If the organ has a MIDI system, one need only
to establish a separate MIDI channel to control the jack box.  Each
toggle on the jack box would be assigned a note on the keyboard for
MIDI identification.  Perhaps middle C would control the "String F"
stop on the lower keyboard.  If that stop needs to be turned on, a
brief perforation, Middle C, is entered on the channel for stops, at
the correct point in the music.  That perforation causes the toggle to
flip on, and notes played on the lower keyboard will now speak on the
"String F" rank.

Using an edit table, the roll could be slowly moved until the next
printed instructions come into view.  Turning on more stops would be
more MIDI notes entered on the stop channel.  To turn off the stop, the
same MIDI note is applied that correlates to the "on" event, but this
second application will move the jack box toggle to off.

The process gets a bit muddy when the roll instructions direct the use
of the "Tonal" pedal.  "Tonal" is Aeolian speak for "Crescendo".  Organ
crescendo pedals bring on stops of progressive loudness as the pedal is
depressed.  Depressing the pedal fully usually turns on everything.

So the instructions say "Tonal 1/2".  But we can't physically move
the pedal, so we have to enter code for what the pedal does.  For the
coding to continue, one must know which stops are turned on in the
standard Aeolian console by pressing the tonal pedal.  One makes a
"sequential pedal chart" showing how the stops come on in order.  When
the "Tonal 1/2" instruction appears, the stops that must be turned on
are found on the sequential pedal chart.  But if some of those stops
are already turned on by prior instructions, entering a new perforation
to code for the "Tonal 1/2" instruction will actually turn off those
stops.

A tally sheet can be used to keep score of what is on and off.  So when
the "Tonal 1/2" instruction includes turning on Middle C, the "String
F" on the lower manual, reference to the tally sheet shows that it is
already on so no perforation is entered for it again.  Think of the
Tonal as being superimposed on what is already set.

While the music plays on with the "Tonal" at 1/2, a set of instructions
comes along saying "String F lower manual" off.  If you were hand
controlling the organ you would indeed turn off that stop, but nothing
would happen as the "Tonal 1/2" position is giving that stop an "on"
command.  What the instructions are doing is setting up the stop
configuration when the tonal pedal is returned to off.  So in coding
for the MIDI, that stop is turned off at the same time the codes for
tonal off are entered.  The MIDI code must emulate what the tonal pedal
does.

What we have now are two sets of roll instructions that have to be
ignored to get the right results.  First, we can't really code the
"Tonal 1/2" action because doing so will turn off something that should
be on.  Second, when the instructions say turn off the "String F", they
really mean "turn it off when the Tonal is moved to off," and we must
delay our code until that point.

The result of all this is when the off codes are entered when the
"Tonal off" command is given, one actually has to turn off more than
what was turned on with the "Tonal 1/2" command.  A system such as the
tally sheet is mandatory to keep track of the stop status.

If you have followed all this, congratulations!  But this is just the
easy stuff with only one stop change.  Often numerous stops are turned
off or on while the Tonal is fully depressed.  This results in delayed
MIDI entries and considerable bookkeeping on the tally sheet.  My
system uses green ink for "on", red for "off", and blue for "Tonal on".
Stop changes made while the Tonal is on are circled in pencil.

An example of a tally sheet is on my old web site that hasn't been
updated in years: http://members.socket.net/%7Ertaylor/tally_sheet.html 

I'll post a second installment later that will deal with the music
found on the Romeo and Juliet roll.

Bob Taylor
Missouri

 [ Bob's earlier article describing this procedure is available at
 [ http://members.socket.net/~rtaylor/convert_116_to_duoart.html 
 [   "Converting Aeolian pipe organ rolls (116-note rolls)
 [   to fully automatic Duo-Art music (176-note rolls)"
 [ An audio recording of the "Bells Of Rheims" music roll is at
 [ http://www.aeolianorgan.com/aeolian/Podcast_4/Entries/2007/3/11_Bells_of_Rheims,_roll_1268.html 
 [ -- Robbie