[ Wayne Lincoln wrote in 190130 MMDigest --

> I have an Ampico A in a Fischer baby grand that plays too softly.
> All parts have been rebuilt on this unit, but I'm having trouble
> regulating the "regulating valves" to play loud enough.

The most important part of Ampico expression is setting the intensities
properly.  Before doing this, it is also important to check the Modify
switch for subdued playing.  Often there is a leak in the switch, or a
hose becomes dislodged and the subdued pneumatics are activated without
your knowledge.

You will also need an accurate vacuum gauge.  Connect gauge at the
bass end of the action stack, by attaching hose to any bass unit valve.
Place ["low tack"] masking tape over the entire tracker bar.  Set the
transmission lever to "Play" and the Repeat lever to "On", set the
Tempo at 80.  Turn on the motor.

Disconnect the two slow crescendo hoses, 1B and 1T, so to allow the
bass and treble crescendo pneumatics to fully collapse.  Set the
Modify switch to medium.  The vacuum gauge should read 20 inches.
If it doesn't, increase the spring tension on the pump (by rotating
the spring, closest to amplify pneumatic) until the gauge reaches
20 inches suction.

Once that is accomplished, set the Modify switch to "Brilliant"; the
gauge should read between 27 and 30 inches.  If not, rotate the screw
in the amplify pneumatic until it reaches 27 to 30.  Repeat the whole
process for the treble end of the system.

To adjust the lowest (softest) intensity, adjust the spring tension of
the crescendo pneumatics.  It should read about 7 inches, or reduce the
tension until the softest notes do not drop out when soft pedal is on.

If this does not solve the problem, there are leaks somewhere.  Check
the ends of the pneumatic stack where they are fastened together by
a long screw.  Often dry conditions will cause leaks at the end joints
of the stack.  In addition, check the unit valves for cracks in the
seams where they are glued together.  Small cracks can be filled in
with hot glue.

It is best to keep the humidity steady, year round, in the room where
the piano is located.  Wide variations in the percentage of relative
humidity is the cause of many problems, including tuning instability.

Often it is nearly impossible to accurately control year round the
humidity in the room where the piano is located. especially in an old
house during the dry heating season.  A room humidifier during the dry
season can do more damage than good!  The excess humidity can condense
somewhere where it is cooler and can cause structural damage to the
house.

I solved this problem by covering the entire piano with plastic sheeting
($2.00 plastic sheeting for painters) and adjusting the humidity under
the plastic cover by a series of wet sponges and water in pans on the
floor.  I agree it is a bit unsightly, but knowing this is protecting
your piano is more important.  In summer I remove the plastic and use
a room dehumidifier 24/7, keeping all doors and windows to the room
closed.

Keeping the humidity steady as possible -- year round -- will produce
rewarding results.  Avoid modern automatic humidity control attachments
on the piano.

Bruce Clark
Interlaken, New York
ampico@ottcmail.com.geentroep [delete ".geentroep" to reply]

 [ The thoughtful piano technicians I know believe the humidity control
 [ attachments give the piano owner a false sense of security.  Better,
 [ they advise, is to monitor the relative humidity with a good quality
 [ instrument and then adjust the moisture with a room humidifier (away
 [ from the piano).  Of course, a whole house temperature and humidity
 [ regulating system is ideal if you have the money.  -- Robbie