At 19:13 -0500 23/3/09, Will Truitt wrote: >Well, JD, you certainly are a good salesman for the concept... ... Maybe, but I'm not sure how much improvement you would effect in a Steinway by the modification you envisage except perhaps in the treble. Every few millimetres in total bridge height will make a little difference and, by simple mechanical laws, increase the stiffness by more than the proportion of the added height to the original, but you will not achieve a step change by so small an increase. As Ron says, the string height in the Steinway is likely to be lower at note 88 than in the middle. There's good reason for this in pianos with studs (agraffes), as I explained recently. Why Steinway continued the practice, using the capo bar, heaven knows. Raising the string height is not the only way to increase the effective bridge height. One alternative is to lower the inner rim/soundboard, possibly necessitating cut-outs in the framing to allow the passage of the bars. I've done this a couple of times with experimental models, and it's a lot of work without a good set-up. A simpler way is to do what Grotrian, Rittmüller and others did and add to the bridge height from underneath. I've never been impressed with the result Grotrian achieved with the double bridge, but I think that's because of their actual design rather than a fault in the principle. This way you have a far simpler task and can increase the effective bridge height as much as you like without changing the string heights and getting all the bother that ensues from this. If I were doing this, I would calculate (or get a better engineer to calculate!) what _width_ of under-bridge would be required for a given under-bridge depth (which must be 1/4" greater than the depth of the bars) to produce a structure that is as stiff as a simple 45-50 mm over-bridge. This would almost certainly result in an under-bridge narrower than the over-bridge. I guess that Grotrian's 'mistake', as I would call it, was to over-egg the pudding. One day I must sit down and do the calcs. Rittmüller, by the look of it, put more thought into the matter. As a man with a very limited admiration for Steinway's supposed genius, I myself would start with a better piano! JD
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