Thanks for replies. My brevity misled Piotr Barcz. The manual volume
controls are the usual two levers, accompaniment and theme, but they
then each are linked to and rotate a thin brass disc which has holes
and slots so that as each rotates it progressively opens holes and slots
connected to the pouches in the dynamic control box. Then the accordions
operate the knife valve(s) as if the Duo-Art is on but controlled by the
rotating discs instead of the intensity holes in a D-A roll.

I advise Ben Gottfried that the quoted serial number is very clear and
is 69257. The other identical piano in this locality in clearly numbered
69284.

I believe we can be confident that the two pianos are from the late
1920s or very early 1930s. There is some anomaly, maybe allocation
of a block of numbers for player grands.

There must be many such Duo-Art grands in the USA. Can we please have
some serial numbers from owners of these "late style" Steck grands?

Harold Ball
Melbourne
hball19@optusnet.com.au.geentroep [delete ".geentroep" to reply]