Actually, the Ampico B did not use sustain pedal compensation.  That was
used only for a time in the 1927-28 Ampicos, and I suspect it was put
there, not by Dr. Hickman who may have brought the "idea" to Stoddard's
attention, but undoubtedly by Charles Stoddard.  Robbie wrote:

>[ In 1927 Ampico also began coding rolls for the forthcoming model
>[ 'B' reproducing system which employed sustaining pedal compensation.
>[ Descriptions of the Ampico B intensity control system and the
>[ loud pedal valve block are at the MMD Tech site, at
>[ http://mmd.foxtail.com/Tech/Ampico/index.html  -- Robbie

The compensator was a "gimcrack" for selling pianos and made no
difference, one way or the other, musically.  I have a good ear for
intensities, and I cannot tell the difference when I've got a roll
on that you should be able to hear the difference.  One reason it's
nonsense is that regardless of the changing pressures in the spring
pneumatic, the pressure (negative) in the compensators remain the same,
which would actually subtract a lot more percentage of force from the
spring pneumatic at low intensities than at high intensities.

Luckily, the compensator is so small it doesn't make any difference,
and a person claiming to hear the difference would immediately ask,
"Why is the degree of compensation so much greater when the piano is
playing softly, than when the piano is playing normally or loudly?"
It makes more sense musically to remove it, than to keep it.

There was no sustain pedal compensator in the model B Ampico.  Hickman
knew by then at least, that compensating the sustain pedal for what
was normal and expected was redundant and incorrect.  Good, bad, or
indifferent, you don't fix cracks in a Rembrandt with putty.

The only sustain pedal regulation is that it was driven by a pressure
regulator to keep it from operating too quickly and thumping.  That is
not compensation.  There was absolutely no other feedback at all
between the expression system and the sustain.

Craig Brougher