Robbie,  I believe the concept of the "half" Duo-Art was stated
backwards, or maybe the one that I have used was backwards.  As far
as I know, the accomp is regulated and the theme follows the reservoir
suction.  This allows for regulation of the base level and for accents
whenever the theme perforations occur.

The theme is completely under foot control. If it were the other way,
with the accomp unregulated, you couldn't have the theme higher because
the accomp would always be at reservoir suction.  By adding another
regulator for the theme you are losing this control, the coding cannot
be overridden except by excessive pedaling, with unpredictable results.
Actually it might be easier to act as a spill valve than as a theme
regulator, but not for overriding the theme coding.  Please let me know
if I have this backwards.

My information is based on one "half" Duo-Art and what I thought was a
logical understanding of the concept.

Spencer Chase

 [ Well, gosh ... My 1917 American-built Themodist has a knife-regulator
 [ which keeps the accomp pressure constant (lower than the theme), and
 [ my pumping controls the theme pressure (always louder than the
 [ accompaniment).  I must study the articles  about the UK versions
 [ of the Themodist; the differences may be significant.   -- Robbie