I would like to add in a different point of view to Julian Dyer's
answer to the question of adding foot bellows to an electric Duo-Art.
Contrary to Mr. Dyer's explanation of "expression boxes with three sets
of valves', "isolating the theme side", "two sets of theme primary
valves" and "crossover switches", I say just connect foot bellows and
you're ready to play -- simple as that.

The one problem that I can foresee is that with the foot bellows, one
is no longer able to control the damper pedal except by the perfs in
the roll.  No need for any backcheck valves since the foot bellows and
rotary pump are assumed to be airtight.  I must say that I am wondering
why Mr. Dyer thinks all this work would have to be done.

Randolph Herr