It has been brought out that there is a delay factor involving
extended lengths of tubing in a tubular-pneumatic pipe organ action.
However, the original inquiry had to do with repetition alone, and
that is what I am taking up here and now.

I think that would be a good question to ask the owner of a Link
photoplayer.  One that I heard years ago had a separate cabinet
containing four endless roll trackers all teed into the lines leading
to the piano.  Even with the tracker cabinet snuggled up next to the
piano (which it wasn't), the length of its tubing was phenomenal,
especially considering that no less than four tracker bars were all
tied in together.  It seemed amazing that it worked at all, but
unfortunately I don't recall how good or bad the repetition was.

Once I worked on a European machine (a Bursens, I think) that had the
bleeds (vents) right in the wooden tracker bar itself.  At the rear of
the spoolbox was a gasketed strip to permit easy cleaning.  I think
this would be a great design for any instrument, especially one with
long runs of tubing.  This way, when a tracker bar port is opened, all
the air passing through the tubing goes to inflate the pouch.  Then,
as the pouch deflates, air passes to the bleed through the tubing,
going in the opposite direction.  Thus, the flow is divided for greater
efficiency and faster repetition.

In a double-valve player action, the primary pouches are generally
a lot smaller than those of the single-valve, thus requiring less air
to inflate and deflate.  The whole point of the (single) cross-valves
in the Duo-Art action is to allow a smaller pouch to control a larger
volume of air flowing out of and into the striking pneumatics.  (Early
Duo-Art grands had longer tubing because the stack was mounted farther
back.)  Still, most any double-valve action will out-perform the
single-valve action at low suction levels, and is far more tolerant
of poorly regulated piano actions.

Jeffrey R. Wood