Jim, I am not very well acquainted with upright pianos so I am assuming you are referring to some sort of dumb bar where the corner of the soundboard is cut off. As grand pianos get bigger a dumb bar is used to cut off the bass corner. I can think of an other reason why this is done (better support of crown) but you may be right in thinking it helps prevent damping problems. One interesting observation is the use of the "pulsator" on the S&S B (who thinks up these gimmicky names?). This strange arrangement acts sort of like a dumb bar. If you think about it, it stiffens the corner of the board with out adding much mass. Apparently, the thing to avoid is an area of the soundboard remote from the bridges that has a low resident frequency. If this happens an area of the board can act like a sound trap (your term). The reason could be two fold: one, this area being remote from the bridges can not be bridled (damped?) by the strings, two, the lower frequency response could hinder the transmission of sound waves to the air. As usual, Just speculating here. Is it just me or do others notice poor damping on older pianos with tired soundboards that lack crown and downbearing? Maybe lack of compression can cause the problem or make it worse. In some cases it may be caused by the design and in others by a deterioration of the soundboard, or, if you are un-lucky, both. John Hartman RPT NYC Chapter PTG
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