A test roll is badly needed that will include diagnostic patterns.
For example--something to test leakage of the bass and treble theme
valves.  This could be done by playing a repeated note(s) in the bass
at a fixed level of loudness while actuating the treble theme at ppp
and then fff (probably with level 2 and 15 Themed alternately in the
treble).  Of course the sustain pedal must not be actuated because it
would allow the volume to build, making it hard to listen for changes
in the bass loudness.

Another test could be to devised to see how fast the level drops from a
louder accent to a softer note.  A series of notes Themed and then
without would be a starting place.  The same could be done for the
Accompaniment.

Linearity of the cresendos is largely omitted in the existing test
rolls, and it probably the most critical to adjustment.  A series of
notes AND chords needs to be taken up though the dynamic range, AND back
down. Further, comparisons between Themed notes and Accompaniment notes
needs to be made throughout this cresendo and decresendo.

Since the ear is not linear in any respect, it is in my opinion, the
least addressed and most critical aspect of Duo-Art engineering.  Room
dynamics aren't taken into account to a sufficient degree.  But that
would mean "tampering" with the sacred factory settings of the
accordians blocks.

I would be interested in other's ideas about effective DA adjustments.

Bill Chapman, in Sunny Santa Rosa