One of my customers wanted to be able to play 88-note rolls on his
Ampico.  I modified the Ampico on/off switch by fitting it with two
extra nipples which opened to atmosphere with the Ampico switch turned
to the off position.  I connected the nipples to expression holes #4,
one each to bass and treble expression units.  You need two tubes, one
for bass, one for treble expression mechanisms to eliminate cross
signals.  The tubes can be connected to #6 or #4, which ever sounds
best.

Paul Manganaro