> At the California Conference, I attended a grand piano maintenance class > sponsored and run by Steinway techs. I was surprised when they made a > specific point of telling us that a piano under tension does not have to > exhibit any crown, yet still sound and work just fine. That's true, there doesn't have to be positive crown under bearing for a piano to sound acceptable through varying dynamic ranges. If the assembly is stiff enough, it will work. What this doesn't tell you is the relationship between crown and bearing. Since crown under compression (from bearing) serves to stiffen the assembly, it's quite possible for a positive bearing load to have reached equilibrium with soundboard crown deflection at a point of zero, or even negative crown. Typically, the only reason crown and bearing are checked at all in field work is if the sound of the piano indicates a problem you are expected to fix. You and I have no idea how many pianos we've heard that performed adequately for their use, but had flat boards. It's when you start measuring crown and bearing and correlating this against sound quality that you start to get a picture of how it works. > This wasn't in response to any questions, it was a topic on their agenda! Baldwin tech always said the same thing. The above being the case makes this a very handy escape clause. Since you can't tell much about the condition of the soundboard by measuring crown (ignoring bearing), the sound production problems in octave 5 that you are phoning tech support about, must be hammer voicing problems. When voicing doesn't get it, it must need the attention of a REAL Steinway tech. > They also said that it might explain why some pianos are so reactive to > seasonal changes while others, e.g. Acrosonic, tend to be more stable. > > Hmmmm .... > > Alan R. Barnard It might? What might that explanation be? Ron N
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