Hi, I currently own three Duo-Art grands with the around the action
tubing, and also a fourth "spare" upper action and tubing blocks.
The two Weber grands, 1929 and 1930, have similar tubing around the
ends, although the stacks are entirely different. One is basically
a "standard" three-tier stack, and the other stack is a two-tier metal
valve stack. The Weber grands only use the Soft Pedal perforation for
the una corda sliding piano action. The "soft" on the spoolbox only
operates the hammer rail lift.
I also own a 1934 Stroud grand with the late upper action. That piano
has also a smaller two-tier stack but standard valves. Plus I have
the spare action which I may use to convert my standard Steinway XR.
The beauty of the "around the keyboard" tubing is that it takes perhaps
ten minutes and you can have the upper action out, and ready to pull
out the piano action for regulation.
If you have access to the AMICA Technicalities Volume V, there is an
article and a diagram of the tubing. If you do not have that available,
I can make a copy of it.
As Bruce Grimes stated, there are several variations of those, however
all of mine have 40 tubes for the stack on the left connection block,
and 40 tubes for the right side of the stack on the right side. _All_
of them are the same in that on the right connection, the first 8 tubes
are for the accordion intensity steps. Also, all of the them have the
soft pedal tubing on the right side.
The left side has the Accomp and Solo Theme tubing, as well as the
sustaining pedal and Duo-Art "on". Two slightly larger tubes are for
the vacuum supply. Again, privately email me and I can send pictures
and other information.