Pete, something else is also wrong besides the fact that your expression
box is not set up properly. I noticed it when you said, "It's still
playing too loudly" even though your top power is only 20.5 inches.

In the first place, your accordions are to be set according to the book,
to start with.  #1 = 1/16", #2 = 1/8", #3 = 1/4", #4 = 1/2", both sides.
The Theme spring should be a heavier spring than the Accomp spring.  You
don't need measurements in the thousandths because that box would never
recognize such hair-splitting accuracy, anyway; also, the accordion
measurements are given as a starting point.  You may end up "adjusting
them a little."

You should plot a curve, using your stack as the "bleed."  Your felt
muffler will never work the way you have it, so do it right or you'll
never get it adjusted.  A 1/4" hole in a flat piece of felt is not the
same as a 1/4" hole through a rolled up 1"-long piece of muffler felt
stuffed into a hole.  So the first thing you will have to do is change it.
It is the "pivot" around which all the intensities from 0 to 10 revolve.

Your chart should be linear.  With 5" as a #0 accomp. intensity, and your
top intensity (#15, no crash)  draw a straight line.  The pressures are
plotted on the Y axis and the intensity steps on the X axis.  Forget the
db meter.  I suggest first setting up the piano intensities the way they
were originally done, then using the db meter if you wish.

Your top pressure should be about 35" or a little more, with a reasonably
tight system, for the Theme response line.  First, adjust the #10
intensity.  The way you do that is, remove the felt muffler and slap a
"Post-It" note over the hole so that its own natural curve allows a little
gap.  It won't be smack-tight.  Operate accordions #2 and #8 and adjust
the foot on that (accompaniment) side to just close the spill.  When you
see the paper pop off the hole by its own curl, then you have it.  Replace
the wad of muffler felt.  Chart the box by beginning with a straight line
between end points.  Then plot your actual response by using all 14
combinations in-between.  Don't fudge it, and you will see exactly how
linear the box really is.

Another thing I am suspecting is that your pump is not doing its job. It
seems to leak at high pressure and can't make it. That can either be the
fault of the pump or the stack valves, or a combination of both.

When your pump is able to plot 35" or more at crash, that does not mean
that your piano will play even louder than before!  That means that now
your piano has full control and will play everything correctly, from very
soft to very loud, but the boring quality will have vanished.

Craig B.