>This was their mistake. They should have done this before embarking >on the design. We'll probably never know for sure. >You at least have to give them credit for originality and for giving the >marketing department something to work with. Most other makers would >have said let's go get drunk and leave it the way it is, who's going to >notice anyway. Oh absolutely, and a post design fix is still a fix if it works. Considering that this design wasn't a run of the mill clone of something else, if they got that far with it they probably had enough collective hard headed ego to insist that it work - whatever it took. People were people then, just like people are people now. >Ron, I pasted this bit into another e-mail and started a new thread. You can >have a look if you like. Oh may I? <G> I await its showing up in my "in" box. >You may be right. I was thinking of the bridge stiffness as part of the >assembly >stiffness. If you can achieve whatever assembly stiffness you want by >rib and soundboard manipulation then there is no need to vary the bridge >stiffness. I was thinking that at the bottom end if you made the bridge too >stiff you might not be able to achieve the flexibility that you wanted even >by spacing out the ribs and reducing their dimensions. At the top end perhaps >it is more efficient to get assembly stiffness by adding soundboard thickness >or rib height rather than bridge height since maple is heavier than spruce >or pine. Ok, here's the deal. I don't consider the bridge to be a rib, and don't really want it to be. I want it stiff enough that it is the stiffest component in the assembly (rim et al aside) so it isn't a variable in the system impedance control. I don't want to have to worry about it, since there are plenty of other attention holders inherent in the process. With the bridge safely and comfortably in the "stiff enough" category, I can juggle the rib scale and bridge placement without having to factor in (engineering euphemism for SWAG) a vastly (that's VASTLY!!!) more complicated interaction of a flexible bridge modifying all my other accountable parameters and shooting me in the foot by producing an effect I didn't anticipate. It gets strange enough without adding dice to the roll. So my approach is that if the bridge stiffness is a design factor, then the bridge isn't stiff enough. If I was producing one design that I could tweak endlessly toward Nirvana over a period of time, it might be a different story, but I don't think so. As it is, I'm doing one-off acoustic re-designs with little or no backlog of refinement history, and one shot at producing the best result I can with the information I have before me - the piano. A whole lot of changes are made all at once, and a whole lot of time and cash are invested before the preliminary results are available for evaluation to see if the results approached the expectation. Under the circumstances, I want bridge stiffness out of the equation, and making them plenty stiff does that for me. >However, as Del has pointed out stiffening the board at the top end has more >effect than stiffening the ribs. I'm not sure where the bridge fits in this >picture. It doesn't, if it's adequately stiff, and that's the point. > That's why pianos like >the Mehlin are interesting, even though I didn't hold out much hope that it >would be a shining example of what could be achieved by unconventional design. I didn't get a chance to hear the finished Mehlin I saw torn down, so I can't say one way or another. I'd gladly buy as many rounds as it took, however, to pick the brains of the designer(s) as to what the thinking and intent was behind all those marketable features. Someone surely had a plan, and I'd love to know the details. >>It's a lovely concept, and a potentially valuable >>forensic tool, but it would sure surprise me to find there was any use at >>all for it in the design process. > >There may never be a place for it in practical design, but I'm not giving up >hope yet. Good for you. Don't... ever. >Control is always a problem when trying to >compare >two complicated things with lots of variables. It's usually almost >impossible to >change only one variable at a time. So drawing conclusions is a dicey >proposition. >However, it's really the only method we have. If we give up on it, we have >no way >of drawing any conclusions or making any meaningful changes. This is where we have to venture into uncharted territory. Best evidence, reasonable adherence to the principals you have already proven to yourself as workable, and the willingness to change your mind if better evidence comes along. The KISS principal is gold in these situations. Ron N
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