Last night I tuned a Yamaha CFIII 9ft. grand for a concert. This is a new piano and is on loan from Yamaha Artist Services. The pianist was having an occasional problem with the sostenuto which made a loud slap under the following condition: First the sostenuto pedal is depressed holding the appropriate notes. With the sostenuto still depressed, she would use the damper pedal. So far no problem. Then with the damper pedal still depressed, she would release the sostenuto pedal. Finally when the damper pedal is released, a loud slap occurs. What I found is when the sostenuto pedal is released with the damper pedal engaged, the sostenuto blade cannot rotate back to its rest position because the spring tension from 70 sostenuto tabs collectively are locking the blade up. Finally when the dampers are released, the blade can rotate back, along with the free falling linkage which makes the slap. With only minutes before the start of the concert, I could not try any adjustments. Last February, Kent Swafford presented a very detailed check out for the sostenuto system, and he described exactly this condition which I quote. "Depress sostenuto pedal. While continuing to hold the sostenuto pedal down, depress the damper pedal. While continuing to hold the damper pedal down, release the sostenuto pedal. The immediate flipping of tabs should make a noticeable sound as the blade returns to its rest position. (If the blade is held too tightly in its mounting brackets, there might be an inappropriate delay in the return of the blade to its rest position. The tabs should not be able to keep the blade from returning to its rest position.)" I have a few questions regarding this condition. Since the blade could not return to its rest position with the dampers engaged, does this mean the sostenuto rail was positioned too far in, thus overlapping too much of the tabs? >From a piano performance point of view, is this a "legal" use of the sostenuto? After all, even if the blade could return to rest, there would still be the ugly noise from all the individual tabs flipping. I tune this piano every week, so next week I could have a chance to make some adjustments. In every other way (I think), the sostenuto was working perfectly. I would appreciate any advice. Jerry Cohen, RPT NJ Chapter
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