Dr. Clarence Hickman of Ampico Laboratories published this data which
relates Ampico B stack pressure to hammer velocity.  (C. N. Hickman,
"A Spark Chronograph Developed for Measuring Intensity of Percussion
Instrument Tones", Journal of the Acoustical Society of America,
Vol. 1, No. 1, Oct. 1929, pp. 138-146.)

code = command code of Ampico B piano
step = "Ampico intensity step"
gage = stack suction, inches of water
 vel = hammer velocity, cm/sec (geometric average of bass & treble)
  SU = Sound Units, decibels

code step    gage       vel     SU

      000    4.25     41.35    30.0
       00    4.65     48.84    31.5
sub     0    5.25     59.33    33.0
canc    1    6.00     71.65    34.6
  2     2    6.80     84.71    36.1
  4     3    7.80    100.41    37.6
  6     4    9.40    119.58    39.1
 26     5   11.60    143.04    40.6
 46     6   15.10    171.43    42.1
246     7   19.5     202.83    43.7
        8   26.00    241.17    45.2
        9   34.9     288.08    46.7
       10   46.25    341.39    48.2

The dynamic range of one hammer is 18.2 decibels, according to
Dr. Hickman's data.

Robbie Rhodes
Etiwanda CA