[ John Buscemi wrote in 141104 MMDigest:

> The question is, when the zero is set it drops out notes on the later
> Duo-Art recordings and on earlier recordings the louder passages are
> _really_ loud -- they rattle the windows.

There are lots of things to say about the Duo-Art and its regulation,
an interesting device to study and enjoy.  I find one of the biggest
problems with the expression box is that the knife valve drive shafts
have considerable friction on account of the felt bushings in the
valve box have swollen, perhaps.  This will make the zero setting
behave poorly as the drive shafts are giving too much resistance.
Try measuring the piano zero gauge reading often and see if you are
getting the same readings.

If any trouble with the box is found, remove the unit from the piano to
work on it.  If it plays the test roll poorly you will have to, anyway.

I would also point out that the chord tests on the test roll are perhaps
more critical than the first test.  Those chords will indeed play and not
play with the intensities on and off.  It's, in fact, an audio test to
see if the gaps in the accordions are correct.  The total movement is
15/16" for the accordions.

Once you get the zero setting nice, try using a water gauge to set the
Theme to, say, 3/4" higher than the Accompaniment suction, for starters.
The gauge is good to use, because when you tighten that pesky set screw,
the setting you thought you had is gone.  Check the gauge as you tighten
the screw.

I set the spill on the bench so that it cuts out with 4 and 2 intensities
on both sides.  If the felt in the side of the grand box or back on the
upright has been changed or replaced, you cannot assume the ambient spill
with the unit spilling is correct.  I guess maybe there is an ideal
reading, probably 20" or so.

I am sure many people who work on the Duo-Art will chuckle because you
know how important to the performance of a Duo is that felt they shoved
in there at the factory!

Ben Gottfried - Ben's Player Piano Service
Richfield Springs, New York
http://www.bensplayerservice.com/