[ Ref. Karl Juelg in 230911 MMDigest ]



If this is like my Gotha Steck Pedal Duo-Art it has an 88- or 85-note

stack, and uses cutout boxes to switch the top and bottom four notes

between operating the notes and operating the Duo-Art primary valves.

There is one of these blocks each side of the spoolbox in an upright.



The cutouts operate pneumatically. Admitting air to the reverse of

the cutout pouches in the box will block the signal from the tracker

bar, and applying suction will let the signal pass through. One set

of cutouts is on the notes and another on the expression, so one has

suction and the other air according to the chosen operating mode.

The switching of the air/suction is done by the selector switch in

the spool box.



The problem of hearing notes play when Duo-Art is selected indicates

that the cutout isn't working properly -- and given that only some of

the notes are sounding it's probably dirt or damage to the pouches,

rather than the air/suction control logic. The first thing to try is

to take the tubes off and blow through, but it may require the unit

to be dismantled. The cutout pouches are simply pouch leather, easy

to replace.



This pneumatic switch technology was favoured by Aeolian and is seen

in various places in Pianola and Duo-Art actions.



Julian Dyer

Wokingham, Berkshire, UK