Phil Dayson (MMD 971210) referred to the lost motion problem which
causes Duo-Art upright players to miss notes when the soft pedal is on
combined with minimum intensity.

Aeolian must have been aware of this right from the start since my 1914
Stroud has a pallet valve attached to the soft pedal pneumatic which
opens to atmosphere a line teed to intensity 1 from the accompaniment
side of the tracker bar.  A second port on the valve was not used.

This arrangement appears on the published 1918 upright tubing diagram
and guarantees a minimum expression level of 1 when the pedal is on and
seems to me to be a neat solution.  If it wasn't used on later models,
I can't think why unless it was the slight loss of resolution (the
steps are now at level 2 increments but only while the soft pedal is
on).

It wouldn't be hard to retrofit a pallet valve where it isn't already
there.  The loss of notes is much more audible than the coarser reso-
lution.  The fifth step level mentioned by Phil is a complex way of
avoiding that probably inaudible resolution effect.

I experimented with my own player and found that turning on level 2
rather than 1 gave more reliable results but that was probably due to
the less than perfect performance of the mechanism.  This would affect
the linearity somewhat more and I would only suggest that as a
temporary fix where missing notes is a big problem.

Since many grand actions use a hammer rail lift for soft pedal, I would
expect to see a certain amount of lost motion before the player action
starts to lift the hammers but I haven't looked into this yet.
Possibly the same approach might work here too.

Perfect reproduction is a laudable goal and judging by the criticisms
of the various CD recordings of piano rolls, it is very hard to tell
how far you are from achieving it.  And that totally ignores the
limitations, errors and editing of the original roll recording.  It
will keep many of us occupied for as long as our enthusiasm can last!

Cheers,
Darrell Clarke
Adelaide, Australia