I've hesitated to say too much about the testing we've been doing here with the "Wurzen whites" because it's still quite preliminary. I certainly wouldn't claim we've come anywhere close to a definitive result, or even a controlled experiment. That's going to have to wait until: (a) I have a grad student who can take the time to do a thorough study, and (b) a new fancy pants micro-tensile testing machine is installed in the lab in June. Note that secondary effects, such as noise contributions from impact, or feel of the key bottom to the pianist, are beyond the scope of this premilinary experiment. Also, instead of trying to observe differences in tone, I was simply looking for a mechanical mechanism that would ALLOW the properties of the punching to directly influence the tone, as well as demonstrating that the key actually does behave very differently on impact with the two kinds of punching. On the second point I will put a couple of video clips on my website to illustrate, showing the key impact with standard green woven and Wurzen white punching (I'll pass on the links when I've got the videos into a manageable size for web-viewing). These don't prove anything, of course, other than showing the felt properties of the Wurzen punchings prevent the sloppiness seen in the decelerating key with the green punching. In other words, the two types of punchings cause a clearly different impact response from the key. Now, on the first point, a static viewpoint (as derived from knowledge of standard regulation procedure and configuration) suggests there is a clear association between aftertouch and the front punching compression phase. However, dynamically (at least in the action configuration I tested) this is far from a clear, or even fixed, relationship. In fact, the simultaneity of statically adjusted events can, and does, change quite dramatically under dynamic conditions. This is really the most important point that leads astray when trying to make arguments for or against a particular explanation of the behaviour of a piano action. For example, in this case, the non-rigidity of the action mechanism allows it to take on a configuration where the key bottom has touched the top of the punching, while the jack is still well under the knuckle, and has barely reached the letoff button. Consequently, a direct mechanical link exists (for about 2.5ms) during the escapement phase, i.e. PRIOR to any string contact, between the pianist's arm, finger, key front, compressing front punching, and through the key and action assembly all the way to the hammer. This is what I meant by demonstrating a mechanism whereby the properties of the front punching can directly influence the behaviour of the hammer before it strikes the string. This doesn't prove an effect on tone, just that it is clearly mechanically possible for tone to be influenced in a significant way by changing the properties of the punchings, consistent with the observations of Andre and others who've tried the Wurzen punchings. Moreover, this explanation would suggest the effect should occur under forte playing, and only with a very well regulated action, consistent with Andre's frequently repeated observations from his experience using the punchings in pianos. Stephen -- Dr Stephen Birkett, Associate Professor Department of Systems Design Engineering University of Waterloo, Waterloo ON Canada N2L 3G1 Director, Waterloo Piano Systems Group Associate Member, Piano Technician's Guild E3 Room 3158 tel: 519-888-4567 Ext. 3792 fax: 519-746-4791 PianoTech Lab Room E3-3160 Ext. 7115 mailto: sbirkett[at]real.uwaterloo.ca http://real.uwaterloo.ca/~sbirkett
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