Mark Graham wrote >I have the Steinway manual, and have always read about levelling strings >but have never had time to get to it. I've seen a few of you mention it >recently, and I had a day to mess with the piano, so I tried it. I was >amazed to find, first, how many unisons were not level, and second, what a >dramatic improvement in sound resulted from correcting the situation. I >will never again underestimate the importance of this step. Halleluiah. Bro', step forward and join the saved. The business of fitting the hammer contact surface to the string it's hitting is the sine qua non of solid tone. You describe cleaning up your own work. The real gravy hits when you get to clean up after other people. Robin Fox wrote: > My thought has always been that the hammers would have mated to the >string heights so that leveling them would disrupt that relationship. So >what >does happen to the string-hammer relations on leveling, or, why does it work? Good, logical question, and one which I have yet to find an answer for myself. The best I can offer is that if you have strings in a unison maybe 20-25 mils apart vertically (-I used to do my string leveling with a dial indidcator), that by the time the string cuts have progressed far enough so that high string is finally getting hit when the low string does, the low string is being hit by a strike surface considerably flatter than the high string (which at this point is a pristine curve). I was called in to listen to the voicing on a newly installed action of a '39 B, and was told by the owner that the tech (a well-respected senior) was going to complete the voicing after the hammers had worn in. Certainly there's nothing wrong with waiting for a little "work-hardening" for a stable voicing, but the apparent absence of any "open-string work" (as Franz Mohr calls it) signaled to me that the tech was hoping that the open strings would disappear once the hammers got cut into. For the meantime it whined badly. Joel Rappaport, joelr@flash.net wrote: >It is most adviseable to do string leveling at the time that you are >doing some maintenance on the action, i.e. lightly filing the hammers >and going over the regulation and voicing for the very reason that Robin >points out. Make that, anytime you you set about to voice. Open strings have a recognizable sound, and any acupuncture on a hammer while open strings still exist is (IMHHHHO) malpractise. If I may ramble further, I'm glad that Claire Davies is focusing on the Una Corda as the key to open strings (or I assume he is based on the convetion brochure description of his minitech and the teaser for it posted here last month by a colleague who'd seen it demo'd.) In 5/96, I posted here an encounter with pianist Anton Kuerti, who was surprized to see me leveling strings (saying he didn't think that it was good for the strings, and that open string work was done by filing the hammer crown). I asked him how anyone could get a good UC sound without insuring that the open string work stayed solid when the action shifted. He said, "Oh I never use the UC, they all sound so awful." (BTW, he's a wonderful pianist and human being, and I enjoyed working with him.) The UC's unique role in open string work rests on this basic principle. You have two surfaces to mate: the line across the hammer's crown and the line across the trichord's three strings (*at the strike point*). You do your best work with each and assume that produces the desired straight lines. But how do you know? Check the pattern of the fit (open/closed/open, c/o/o, whatever). Shift the xn with the UC. If the pattern stays the same (albeit without the participation of the LH string), the lack of straight line is in the string leveling. If it shifts, the out-of-level is with the hammer filing. (In shorthand, if o/o/c becomes .../o/c, string level. If o/o/c becomes .../o/o, check the squarenes of the crown.) There are a few curve balls (as there are in fitting a block to a plate), but it's the UC which squares away the open string work, and in short order. Assuming I arrive at this step with correctly filed hammers, I usually find that that assumption is 95% correct. (And I am grateful to this technique for the 5% correction in my hammer filing.) This subject was covered in the 10/90 PTJ, and I'm sure it'll be covered again. Ed Foote <A440A@aol.com> wrote: >It is not a beat, but a sound that my recording engineer friends all >recognize instantly as a phasing change. Since what affects the unison also >affects all intervals built with it, it only takes a handfull of unmated >notes to alter the entire sound of the piano,and, as was noted earlier, the >change is very noticeable when you get all the strings mated. I've puzzed over this for years. Is the degree of out-of-phase a function of when each string starts its oscillation? Would that imply that the important instant is not when the three unlevel strings get hit by the hammer, but when the hammer in its rebound leaves contact? Certainly unlevel strings would be unequally displaced by the hammer, and would be restoring themselves with unequal force. Certainly the timing of the initial contact by the hammer of unlevel strings would be a function of the vertical distance involved in the out-of-level and the speed of the hammer at impact (ie., the time interval required during the decceleration at this contact for the hammer to contact all three strings). All this being applied to the period of the oscillation. This is how I imagine the timing of hammer contact (the engage-phase). How does the behavior of dis-engaging strings affect the phase differences thereamongst? I'd love for someone to shine a flashlight on all this. Certainly, the RCT could measure our favorite attributes of string vibration (decay, inharmonicity, frequency) in a set of unlevel strings accurately enough to get us started, assuming that the business of isolating each string doesn't itself affect the individual vibrations. In 10/96, Barney Ricca (Mr. "Think Like a String") was readying a device to measure both vertical and horizontal modes of vibration of three strings in a unison ..simultaneously (-that's right, six readings). But even he, physicist that he is, would tell you that such measuring devices will yield far more questions than answers. I gotta go ta woik....
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