Richard and Brian, Del is the brighter (and noisier) experimenter of this bunch and knows far more than I about this subject so I will stick to some generalities. > Is there an ideal shape / size of termination? The consensus is round with a 1/16" radius If you carefully examine a good agraffe you will see the inside is shaped like a nicely rounded doughnut. This is critical to know if you are going to "reshape" agraffe holes. There is always going to be some leakage across terminal points simply by the nature of energy flowing through a spring. Energy going past a terminal point is energy lost for our purpose, volume and sustain. There may well be a "best" form of termination but I don't know what it would be since you can find two and three types of front "bearing" types on one piano. I have know several outstanding pianos that used agraffes throughout and some that were not so outstanding that did as well. I believe the capo de tasto bar was invented to save time and effort and a stronger system mechanically and not because it is inherently superior. My opinion. Just consider the amount of work involved in 88 agraffes!! I have also observed that what the person at the front of the piano can hear is very different that heard just five feet away. By the time the sound reaches the back of a hall it is nearly impossible to tell one brand of piano from another brand if they are voiced similarly. Instead of concentrating on duplex termination I think a greater return would be in concentrating on soundboard and bridge performance. The less compliant the bridge the more noise beyond terminations. Duplex bars should not be made of steel because the electrostatic bonding of similar metals can cause rust bonding and certain metals gall when under stress. These are the reasons brass nuts are used to hold exhaust headers on, they will not bond to the cast iron. Brass is a good material because it is available in many types, sizes and styles, does not gall, looks pretty, does not corrode the same as steel and is easy to work. The lower the angle of deflection after terminal points the more noise can occur especially under heavy blows. The high the angle the harder the tuning because of rendering problems and ultimately tuning stability. I think anything under 12 and over 15 degrees will cause problems. Look through the archives for past mumblings from Del and get copies of his articles on the subject from the Journal. On those noise duplex systems, I have fond that careful unison tuning and non speaking string tension can help a lot. Look at the situation and see how you might change the system without tear down. It may not be possible but sometimes the duplexes are movable. Not likely with the strings on but it may be possible. I have exhausted what I think I know although there may be a nugget or two buried somewhere down there in the empty well. Newton
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