The first line of my post below should have read: "With all due respect to Hal Lyne, soundboards with that style of rib installation are no MORE prone to loss of crown than are any other." Sorry about that... a loose connection between the brain and the send button. -- ddf -------------------------------------------------------- Delwin D Fandrich wrote: > robert moffatt piano service wrote: > > > This bit 'o wisdom was passed on to me from my mentor's mentor, Hal T. > > M. Lyne. Hal noticed the same problem in Wurlitzers that are 20+ years > > old. The problem, in Hal's experience, was that the ribs which support > > the soundboard (giving it its 'crown') are not embedded in the case; > > they are simply slapped onto the back of the soundboard. After time, > > because there is no additional reinforcement from the case, the wood of > > the ribs and soundboard simply 'gives out' and the downbearing on the > > bridges flatten the soundboard. Ergo, the whole danged thing goes flat. > > So, check the ribs and see if in fact they are just slapped on the > > soundboard. If so, then that's probably why the thing has started to go > > flat in odd places. > > > > How do you fix it? Don't ask me. I'm just an apprentice and have > > enough trouble setting a concert temperament. Of course, I don't have > > any flashing lights to help me out so it's taking me a little longer to > > learn. Then again, I hope to be a better tuner for it, neh? > > > > If you've any questions about possible repairs, you can E-mail my boss > > directly. > > > > Cheers! > > > > Scott Pickett > > Philosopher, Projectionist & > > Apprentice Piano Tech. > > > > From: Robert Moffatt Piano Service > > Calgary, Alberta, Canada > > ----------------------------------------------------- > > With all due respect to Hal Lyne, soundboards with that style of rib installation are no less prone to loss of crown than are > any other. The practice of notching the soundboard liner and insetting the rib to the notch is simply insurance against glue > failure. That the industry still insists on promoting -- and even featuring -- this practice as gospel has as much to say > about its worship of tradition as it does about its general lack of understanding about how soundboard systems actually work. > > As I've said before, in simplistic terms, the soundboard system functions as a two-dimensional, wave-carrying panel. > Acoustically, it would be desirable for this panel to have a "hinged" parameter. At least through most of the scale. (An > argument could be made that the additional stiffness gained by insetting ribs to the liner might be beneficial through the > treble section -- i.e., approximately the upper third of the scale.) In the bass and tenor sections, however, the practice is > generally detrimental to the sound of the piano. More than once I've puzzled over the marketing hype that promotes both > tapered (i.e., "diaphragmed") soundboards and inset ribs at the same time. The two ideas are contradictory. > > The practice does, of course, demand good gluing practices. Practices Wurlitzer had only a loose acquaintance with. I once > purchased an unstrung back assembly from Wurlitzer for some experiments. I got really busy just after receiving it and didn't > get to it for a couple of years. By then the back assembly was already showing signs of disintegration. Glue joints were > already failing, and the back hadn't even been strung yet. > > -- ddf
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