I read with great interest (as is the case with all of Craig Brougher's
submissions) the article on appropriate leakage in the Duo-Art.  It
encouraged me to mention a modification to my Duo-Art that I have made
that I know will elicit much criticism, but here goes.  It is time for
some debate on the MMD.

I have a fine, well-restored and never abused 1914 Steinway Duo-Art
upright.  Due to the fact that it lives in the mountains of Northern
California in a house heated primarily with wood, there has been a
self-imposed limit to the degree to which this piano can be regulated.

Every season presents a different challenge and in spite of my
obsession with perfection, I have given up on the idea of a note-to-
note regulation with respect to the player.  My piano technician is an
excellent voicer and the player is very good (I have heard few better
pianos), producing truly enjoyable music.  Having said all this, I will
mention the modification which I believe produces good results, but
which I can't evaluate completely due to the limitations mentioned
above.

I installed a remote pump, which I feel is a great improvement to the
overall musical experience.  It is possibly the best improvement one
can make to an otherwise fine instrument.  The pump, which is an Ampico
box pump, is located below the house and is driven by a variable speed
motor that allows matching the pump capacity to the seasonal demands of
the piano.  The only remaining noise with this system was the damn
noisy spill valve that was used in the uprights.

I decided to try improving this.  I have a late model Duo-Art regulator
of the fan pneumatic type (not installed in this piano) and I copied
the spill valve from it.  It uses a double check valve, connected to
the accomp and theme regulators, whose output is the greater vacuum
level of the two.  This output is used to control an Ampico type
amplifier valve.  As the vacuum increases, the closing force on the
valve increases and the leakage therefore decreases.

It acts very similarly to the original spill valve but is much quieter
and is easier to adjust.  If you need more leakage at low stack levels,
you can get it and still have a tight stack at the higher levels where
the effect of a bleed would be to limit the top range.  Of course, you
are on your own to regulate a piano with this modification, since the
effect of the original spill valve needs to be mimicked properly.

I hope to not be apprehended by the restoration police for this heresy.
Everything is easily reversible, no parts were removed, destroyed or
modified other than a 1/8" hole in the in the theme side of the
expression box.  The result is that I can have a player that plays very
well during the entire year without the need for constant adjustments.
I just turn a single screw and adjust a knob every now and then if
needed.

Spencer Chase