Gentlemen,  In the regular Aeolian Duo-Art pipe organ rolls, the
roll tempo was stamped at the beginning of the roll and you manually
set your player accordingly.  In some late rolls, after the Concertola
was available, Aeolian put a punched code, just a few holes, at the
beginning of the roll.  The Concertola could read them and interpret
the tempo from them.

Does anyone know the code for re-punching these temp holes?  Which
combination of holes set up what tempo?

Also, how did the Concertola interpret these tempo holes from what
tracker bar holes, lower or upper, and in what combination.  I presume
that the appropriate tracker bar holes had parallel tubing to some
special valve box that would then set some form of speed control.
Can anyone enlighten me on this?

Jim Crank