Kent Swafford wrote: >I'm not usually one for puzzlers, but I think this one is interesting; >I'll post later why I think so. > >This week I was getting a Steinway D ready for a concert that was >tonight. I put a fairly complete regulation on the action. I found that >the sostenuto was working poorly and regulated it, but the pianist >complained of a cracking sound upon release. This is a first-rate pianist >and I knew that the complaint was likely to be valid. Here is what I >found: > >Hold some notes down, engage the sostenuto, play other notes and engage >the damper pedal, release the sostenuto pedal. At this point the monkey >does not descend, but stays up. When the damper pedal is released, the >monkey comes down with the "crack" that the pianist complained about. (I >noticed that when the damper pedal is keeping the sostenuto engaged, one >can engage the una corde with no effect on the sostenuto; the monkey >stays up.) > >How can this be? How can the damper pedal keep the sostenuto monkey and >blade in the engaged position? > >Kent Swafford I failed to correct this problem before the Saturday night concert; the pianist was forced to change fingerings to deal with the situation. I was very unhappy. On Monday there was a voice mail waiting for me from the pianist in which he consoled _me_. This was not cool. (It is little consolation if one thinks of the solution to a technical problem after the fact, like 20 minutes after being presented with the problem while the doors were opened for the audience _10_ minutes after being presented with the technical problem.) Newton wrote: >Some things come immediately to mind: > >1: the blade bushings are too tight so [the blade] will not rotate freely. Bingo. Newton knows; it's _always_ the basics, even when you think it's not. The first step in piano work is to take care of the basics. The second step is to make sure the basics are taken care of. I forgot the second step. Jon Page wrote: >Is it the solid tabs in the vertical flange holding up the sos. blade? >Any notes held down while the sos. is released causes a knock in the key as >well. > >This is why the spring type tabs are better. Good point. Read on. Jim Harvey wrote: >(a) Action position, due to keyframe guide pins/plates shifting or being >worn out; >(b) Failed to do inventory before closing the patient -- something left in >the cavity; >(c) Performer exercising system in a manner that God (or S&S) never intended; >(d) I had adjusted blade bearing points (pivots) too tight; >(e) While "reaching over" blindly, I had positioned the monkey spring >offsides; >(f) The blade in/out adjustment screws were not on the "magic" moment of >torque, and subsequent handling caused the blade to shift; >(g) Any and everything dealing with trapwork underlever spring placement, >orientation, and seating; >(h) Damper stop rail had (once again) been 'hammered' out of position; >(i) Monkey actually was damaged (cracked), and failed to follow the same >path twice in succession, especially when under load. >(j) Monkey "keeper" (tab that's attached to blade) was bent (see item C). > >Moral: there may have been a pre-existing condition that you wouldn't have >noticed during the regulation process. When you regulated the sos properly, >the condition was exacerbated. This is quite a list and shows some of the complexity of dealing with this mechanism. There were signs that the sostenuto had been a problem for some time in this piano. The leather punching was missing from the trap above the pedal rod; the blade brackets were bent upwards leaving the blade too far high. Regulation was sorely needed, but I missed an underlying problem. Del wrote: >I don't know what it was that your pianist was doing, but unless I'm missing >something, using the sostenuto and damper pedals as you describe is not >normal >to the mechanism. In fact, it sounds to me as if the mechanism is working >pretty much as would be expected when used in this manner: > 1) Play some notes and hold them down, engage the sostenuto. Normal >operation, the sostenuto rod rotates and contacts the damper lever sostenuto >tabs and suspends the damper levers associated with the keys being held down. > 2) Play some other notes. The damper levers start to rise and their >sostenuto tabs contact the sostenuto rod lip and rotate, allowing the damper >lever to continue rising without binding. The tabs do not engage the >sostenuto rod lip, but bear against it. > 3) Engage the damper pedal. All of the remaining damper levers rise >and all of the damper lever sostenuto tabs contact the sostenuto rod lip. >The >damper lever tabs function in the normal manner by rotating away from the >sostenuto rod lip, but they do apply an upward force against the lip. The >sostenuto rod lip is now caught between tabs both above and below. > 4) Release the sostenuto pedal and the pedal and trapwork assembly >returns to the normal rest position. There is a trap spring that assures >this. But there is only the monkey spring to return the sostenuto rod to >rest >position. It is not strong enough to overcome the friction of the >brackets as >well as the spring pressure from all of the damper lever tabs holding it up. >As the damper lift pedal is released the sostenuto rod lip is released >suddenly allowing it to snap back into place and allows all of those damper >lever tabs to snap back all at once. They make a "cracking" sound in the >process. As would be expected under the circumstances. > >Steinway did not expect that the sostenuto pedal/rod would be used in this >manner, I think. Does it work normally when used normally and correctly? If >so, you might consider a demonstration using a model action showing the >pianist what is happening. I.e., teaching him/her how to use the mechanism. This is what I would have thought also, but I must have been wrong. Why would Steinway have gone to the trouble and expense of moving from solid tabs to spring-loaded flange tabs as Jon Page noted if not to allow the tabs and blade to better co-exist, to both let the tabs turn down when coming up underneath the blade and then allow the blade to flip the tabs out of the way and return to the at-rest position in the above described situation? There is no way that the tab springs (even 67 or so of them) could hold the blade up against the monkey return spring without assistance. Extra friction in the blade bushings _could_ provide that extra assistance, resisting the push of the monkey return spring and "assisting" the tab springs in holding the blade in place. I'm just saying that the blade bushings should not provide this assistance. Ed Foote wrote: >Time to ask a few questions: > On this clacking sostenuto, is this a worn part, or is the answer totally >in adjustment? Also, will the sos. cam stay held up by the damper pedal if >there are no notes played? If so, it is like Del said, the monkey spring is >not strong enough to overcome all the tabs on the underlevers. > If not, then we need another clue.... >Is this a worn part, or is the answer totally in adjustment? >Still wondering, There will always be a clatter sound if the sostenuto is released when tabs are on the underside of the blade. Apparently this sound was not objectionable to the pianist I was trying to serve last week. The objectionable sound happened when the sostenuto pedal was released but the monkey and blade were not released, introducing a gap in the trapwork above or below the sostenuto pitman. When the damper pedal was released the monkey spring would pop the monkey down with an objectionable "crack." I have tested all the Steinways I could since Saturday. Here is what I have found: Passed = tabs unable to hold blade Failed = tabs hold blade Concert artist's home B, 25 years old, rebuilt here in KC, assumed to have passed since this is where he worked up these pieces. A new CD in St. Louis, assumed to have passed since the pianist had no problems with his pedaling at his warm-up concert the weekend before. CD95, failed at Saturday's concert. My M, passed. Customer's L, recently expertly rebuilt in KC, failed. Customer's M, independently rebuilt in NY state 2 years ago, failed. Customer's M, rebuilt in KC several years ago, passed. Every new Steinway grand currently on the dealer's floor here in KC, passed. My conclusions are: 1) Pianists should expect to be able to release the sostenuto when tabs are against the underside of the blade; this is within acceptable practice if they are willing to accept the clattering of the tabs. 2) Technicians don't pay any attention to this but should. I think we are messing up these mechanisms. To all the other tests of proper sostenuto functioning, we should include the following: Depress the sostenuto, depress the damper pedal, release the sostenuto; the immediate sound of flipping tabs will be the sign of proper operation. If the monkey and blade do not release until the damper pedal is released, fix it. Kent Swafford
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