I am writing in answer to a query placed several days ago, regarding
the Duo-Art organ tracker scale [020625 MMDigest].

Since my recent initiation, I have learnt not to be to authoritative
regarding just what the Aeolian company always did in a given set of
circumstances, since you often find that there were so many exceptions
to rules you thought you had discovered.   The tracker scale for 176
"note" rolls is no exception.   Here is how I think it was intended:

From 58-note Orchestrelle days, holes 1-13 were designated "pedal
notes" and, in addition to playing the lowest manual notes, they played
16' C chromatically up to the octave above, using reeds in a special
sub-bass section (usually at the back of the instrument).  The many
Orchestrelles that were equipped to play 116-note rolls used the bottom
13 holes (whilst on normal coupling) to do exactly the same thing.
(My model F Orchestrelle cannot actually cause the top row of holes to
play these pedal notes, but I have seen some which were tubed for it.)

The Duo-Art is a refinement of the above scheme, and by use of special
coupling switches and appropriate activating holes cut in the roll,
plays all 32 notes of the pedal keyboard.  It had to be able to do
this in order to record human organists who are known (sometimes) to
use all of the pedal keyboard.

In order to see how the Duo-Art does this, and to write this article,
I studied an original tester roll, and this is what we see.   All
thirteen holes of the pedal section are used (now, in fact, numbers
31-43 since the first 30 holes correspond to Duo-Art functions) but in
the "not immediately obvious" way which follows.

Pedal  hole  coupler hole
note   cut   cut

First octave
C      31    none
C#     32
D      33
D#     34
E      35
F      36
F#     37
G      38
G#     39
A      40
A#     41
B      42

Second octave
C      43
C#     32    9
D      33    9
D#     34    9
E      35    9
F      36    9
F#     37    9
G      38    9
G#     39    9
A      40    9
A#     41    9
B      42    9

Third octave
C      43    11
C#     32    11
D      33    11
D#     34    11
E      35    11
F      36    11
F#     37    11
G      38    11

To add to the complexity, Duo-Art players always seemed to have a
coupler which allowed manual 2 holes also to play the pedal notes:
the "pedal upper" function hole, number 176.  No surprise in that,
but not all players had the necessary coupler switches to act with
holes 9 and 11.

Of the three cabinet type players I've owned, only one does.   My
Concertola, however, has these couplers and quite a few other devices
besides, awaiting exploration.   I hope this helps.

Paul Morris