Duo-Art Questions
By Spencer Chase
How about some opinions on the following Duo-Art questions:
What is the correct (original) material and configuration of the upright spill valve muffler felt? Can the material usually found there offer the same resistance and flow limitation of the grand spill muffler felt?
How much does the vacuum drop for each note played (at low vacuum levels like 5 to 10 wci), and does it recover all or in part while the notes stay on? Ampicos drop very little and recover very quickly. I believe that properly restored Duo-Arts drop 0.25 to 0.5 wci per note and recover perhaps half of that, but stay low as long as the notes are on. I have measured several pianos so far. What are your values?
I remember hearing a rumor about what the editors used as a value when coding rolls. Does anyone know what this value is supposed to be?
Many rolls have themodist coding (snakebites) with the theme set at 0 or some other level which is lower than the active accompaniement level. Is this a vestige of the editing process which produces no effect and was therefore not removed, or was this used to achieve a desired effect? I have heard many opinions but can't recall any that made much sense.
All that opening the theme valve does (when the theme regulator is lower than accompaniment) is connect a small volume of expression box passageways and theme regulator pneumatic to the stack through the theme valve. Is this used to drop stack vacuum quickly? Duo-Art stacks drop very quickly anyway. I have measured stack vacuum while these strange codings are playing and have not noticed anything happening. Maybe if I know what is supposed to happen, I can watch more closely for it. Examples from particular rolls would be helpful.
Spencer Chase
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(Message sent Wed 4 Sep 1996, 07:30:48 GMT, from time zone GMT-0700.) |
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