I also, think that this is the most plausible possibility. I kind of remember trying to get a false beat on my monochord with no success. My method was to raise the string off the bridge. I also, have had several conversations with Harold Conklin about this. He felt rather strongly that the technicians practice of tapping the string down was detrimental to the piano. I didn't believe him. But with the passing of time his voice has haunted my consciousness and I have felt a little twinge of insecurity every time I do it. Ron's explanation is well thought out. Perhaps with a little time on my hands I will attempt to do something similar on my monochord. This bridge surface deformation is a serious thing. We have purchased instruments from some foreign makers over the last ten years. Most of them sound very good at the time of purchase but give it two cycles of seasons or so and the sound quality tends to deteriorate. The decline is very noticeable and has nothing to do with the amount of use. I have often suspected that the caps on these bridges were not hard enough. >On Mon, 14 Apr 1997, Ron Nossaman wrote: > >> Interested participants, >> >> I'd have to go with Bob Davis and Jim Coleman Sr. on this one. >> >> Further thoughts: Playing with my third tuning today (K.Kawai grand), I was dinking around with the false beats I was getting in octave 6. ALL of the beating strings cleared up with a slight pressure on the side of the bridge pin opposite the string. Gotta be loose pins. Light seating helped on SOME of the beaters, not all. Probably floaters, got them down where the horizontal scrub on the bridge overcame pin flex. While playing with this, I thought of another possibility as to how strings get up on bridge pins. >> >> When a pin is originally driven into the bridge, the part of the hole that has had the least amount of pin pushed through it is the very bottom. Since the bottom of the hole experienced the least wear and trauma with pin insertion, it ought to have the tightest grip on the pin, with the loosest fit occurring at the top, or entry point. The piano is strung and the strings are seated on the bridge. With high summer humidity, the bridge swells. It grows taller, the pin does not! The pin, gripped most firmly at the bottom, has the top of the bridge literally sliding up it, taking the string with it. Since the extreme side bearing of the string on the pin puts the net (side&down) bearing angle at something near horizontal and probably not far from 20 degrees from PERPENDICULAR (thanks Mike) to the pin, when the bridge dries and shrinks, the string stays up. Meanwhile, the extreme sidebearing makes the string very hard to push up the pin and mashes a GROOVE in the top of the bridge. This movement also saws the bridge pin against the top of the hole, at a side pressure somewhat less then the string sidebearing force (minus spring of pin), with each cycle. No wonder the holes oval out and the pins get loose at the top! If the strings are tapped down when they are noisiest ( Winter, pianos get really clear and sweet when the humidity's high and don't need it ), the bridge top will again be more deeply grooved with the next high humidity cycle. Even if they are tapped down as gently as possible, they will damage the bridge on the next cycle! Epoxying the bridge pins in solidifies the column of wood immediately around the pin and severely limits it's vertical movement, relative to the pin, with humidity changes. If this is a good model, the tapping isn't what does the damage, it just makes it possible for the bridge to crush itself. I like this explanation. I think it's logical and simple - Ocham's Razor -. The simplest explanation is probably the correct one. What do you think? >> >> With some trepidation, Ron (simple, ask anyone) Nossaman >> **************************************************************************** Michael J. Wathen Phone: 513-556-9565 Piano Technician Fax: 513-556-3399 College-Consevatory of Music Email: Michael.Wathen@UC.Edu University of Cincinnati Cincinnati, OH 45221-0096 http://www.uc.edu/~wathenmj
This PTG archive page provided courtesy of Moy Piano Service, LLC