In response to Terry Smythe's query on the 9-holes-to-the-inch
15.25 inch wide rolls he has encountered, these were made to play on
a Melville Clark piano which had two independent pneumatics stacks,
one of 88 notes and one of slightly less than 65.  Each had its own
expression regulator of the Apollo X or Amphion DynaChord type.

The supply spindles and the take-up spool telescoped so as to be able
to play standard width rolls.  The tubing to the tracker bar was such
that the middle was laid out exactly as the tracker of an Apollo X or
other piano designed to play QRS "expression" rolls (not Recordo rolls).
The additional holes on the wide tracker were tubed to the second stack
and expression regulator.

The piano was able to play the two stacks simultaneously at different
intensities.  In the note range where both stacks covered most of the
keyboard, notes could be played at different intensities even when
struck concurrently, something no other reproducing system at that
time could claim.  The particular instrument I repaired was a
combination electric and foot pumped upright with the Melville Clark
spring motor for roll drive.  Even though it was thirty years ago,
I can still recall many of the details if there is further interest.

God, that makes me feel old!

Bob Hunt

 [ We have a new web page for the 15.25-inch-wide piano rolls,
 [ visit http://mmd.foxtail.com/MMMedia/QRS/Apollo/index.html
 [ -- Robbie