Author's Subject: Getting a Duo Art to Play More Than 80 Notes

     Ted Baxter, in the 980522 MMD, posed an interesting question about
coming up with a way to play more than 80 notes from a Duo Art roll.
I'd suggest the way to approach this is to use the shut-off port to
trigger a device to shift the bottom 4 notes of the Duo Art roll, that
is C#, D, D#, & E, to play the bottom 4 notes on the piano: A, A#, B,
& C.  Musically, using a chord with an interval of less that an octave
in the extreme bass is not very satisfactory so it should be extremely
rare to have any need for two notes to sound simultaneously in the
lowest 8 notes of the scale.

     There's probably many ways to do this.  One way would be to get an
extra cut out block like the one used to either shut off the bottom
4 notes or the accompaniment accordion dynamics, tube that up to either
play the bottom 4 notes of the piano from the bottom 4 notes of the Duo
Art roll when there's a perforation opening the shut-off port or play
the bottom 4 notes of the roll when the shut-off port is covered.  The
shut-off port would have to operate two valves to do this:  one valve
would supply vacuum awhile the other supplied atmosphere when the port
was closed and they have to reverse their positions when the port was
open.  This should be quick acting and would not require in interruption
of the expression coding.

     I don't know if there's much reason to extend the treble end of
the range because missing a note up there is not nearly as devastating
to the performance as the lack of a needed low bass note.  However, a
second device identical to that used to shift the bass notes could be
rigged up and simultaneously triggered with the bass device by the
shut-off port.  You also have a little different musical situation in
the extreme treble, however, as it is quite musically successfully to
play chords involving 2 or 3 notes in the top 8 notes of the piano
making the simple shifting of the top 4 notes less useful.  This,
coupled with the fact that you often may not want to shift the treble
notes simultaneously with the bass notes, leads me to feel like it'd
be better to leave the top four notes alone.

Regards, Dick
Carlsbad, NM