On Feb 25, 2011, at 10:23 AM, Fred Sturm wrote: > But the element of hammer string contact is king, when it comes to > consistency of voice over a range of force, and that part of the > foundation is critical. A couple more words on this topic of hammer/string contact. The classic situation, which has been measured electronically and also shown visually in high speed videography (I think it was a Kawai film I saw) can be described as follows: The hammer strikes the string String is driven upward by the impact, and actually loses contact with the hammer At this same point of impact, the hammer's upward motion is slowed almost to a stop, but not quite, still rising a bit String wave is reflected back from the front termination (agraffe or capo), reversed (downward rather than upward) and comes back and hits the hammer, or at any rate the two collide a second time by moving towards one another The hammer's upward motion is likely stopped or at least almost, and the second collision produces a second wave toward the front termination. This scenario recurs one or two times, until one of the returning waves actually pushes the hammer off on its downward trajectory. All this happens within maybe three milliseconds, and generally is complete before the first wave toward the bridge reaches it. The result is the timbre of the blow, the mix of partials that will resolve after the initial attack sound has passed. The repeated contacts with the string damp upper partials - the faster the hammer gets away, the more upper partials are generated (and/or the stronger they will be relative to the fundamental). Now if we introduce some chaos to this scenario, in the form of the hammer wobbling side to side as it approaches the string (travel/ square), the hammer hitting one or two strings before the other two or one (mating or result of travel/square), the whole interaction becomes far less predictable. Different forces of blow will produce different results in somewhat random ways: if the hammer is wobbling (vibrating) side to side, sometimes it will hit square on, sometimes the left will hit first, sometimes right, sometimes in between, depending on the precise timing of the velocity of the hammer. Each of these scenarios will change the force applied to the strings and affect the timbre because of the resulting interaction, and it will not be lined up with the force applied to the key. SImilarly with the out of phase caused by lack of mating, with the reflecting waves having different amplitudes and having an unpredictable interaction with the hammer. In any case, the above is what I picture in my mind's eye. Experience shows clearly that refining travel/square/mate yields an enormous improvement in focus of tone, and in predictability of voice. When you play a series of notes at pp, at mp, at F, etc and some stand out at one level, others at another, I believe it usually has something to do with this factor, not to gremlins in the felt. When you continually insert needles to even things out in this situation, often the results become worse and worse rather than improving (the particular hammer may be somewhat better at that level, but other problems emerge at other levels, including often the result that that hammer is lacking at FF). As I have continued to focus on these aspects, I have found that when I sit down to play, there is far more confidence that what I want to do will actually happen, that the piano will suddenly "start to speak": I think what I want to hear and I hear it, it happens. There is less of an uncertainty, where I do what I need to do but don't know precisely what to expect, and then I hear something a little different and try to adjust. It isn't just me. I have done this on a number of clients' pianos (serious pianist, mostly professional), that is to say, taken a "good ball park specs piano" and refined these factors, and their response has been amazement: Wow, I really like to play my piano now, so much more than before. What did you do? Regards, Fred Sturm fssturm at unm.edu http://www.youtube.com/fredsturm
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