>>Yo - action dudes: >> >>Well it's about time I earned those oatmeal chocolate chip cookies which >>Bill very kindly sent mmmm. Thanks much Bill for the treat. >> >>I have revised the slides (on my website), converting into a very brief >>article about inertia/leads, adding some discussion about the general >>case of a real piano [as opposed to ye massless beam etc.], and clarified >>the concept of breakpoint. I also included a page with the simple >>derivation of the relevant formulas on which the graphs are based, in >>case anyone wants to go through those - nothing more than simple high >>school physics here. http://real.uwaterloo.ca/~sbirkett/key_balance.pdf Stephen, Thanks for sharing this with us. I like to think that some of what we discussed here influenced the article. >>.............. >>>Ric B wrote: This seems at odds with the idea that the key would be >>>more difficult to control in the soft zones for the balanced key then >>>the non balanced key. >>>It would seem (intuitively) to me that one would have better control >>>when the slope of the acceleration is slight. And this regardless of >>>which zone we are in. .... >> >>another someone (Phil F) commented on this: >>>This is an interesting point. I have to agree with you that intuitively >>>it would seem to me that the action setup with the most shallow slope >>>would be easiest to control. Less change in acceleration per change in >>>force. The action would be less 'touchy', so to speak. >> >>Yes. This is one certainly possible interpretation - I added some >>comments on the subject of control in the article version. I did say in >>the original slides that the question of "more or less difficult" control >>was "arguable" ["some might believe" etc.] It really depends on whether >>it's easier to control smaller absolute forces over a shallower slope vs >>larger forces over a steeper slope [this in the soft zone]. The answer is >>not unequivocal and needs investigation. >> >>Stephen I think this question of slope is important and would be interesting to investigate. It would be interesting to know if the desired course is to have the steepest slope, the shallowest slope, or something in between. Also, whether this seems to be something universally agreed upon by pianists, or is something that is very pianist dependent. To quote from the article: --- 'In the soft zone the leaded key permits a greater range of force to be used to effect a smaller change in acceleration. In practice this may be considered to make the key less sensitive to variation in applied force, i.e. easier to control. Alternatively, the leaded key requires control of smaller absolute forces, which might imply that it is more sensitive, but harder to control. The interpretation of key control in the soft zone is therefore not unequivocal, and may depend on a pianist's degree of training, skill, and other factors. Experimental investigation would be interesting. In the hard zone the results are not ambiguous, since fine control becomes less of an issue and the leaded key is always physically more difficult to accelerate to achieve a given volume level, i.e. requires more force for the same volume.' --- As you say, in the hard zone the results seem unambiguous. In the hard zone the unbalanced key seems to represent the ideal, or to say it another way, the steepest slope is the most desirable. I suppose the investigation of the slope in the soft zone could yield two results: 1. The steepest slope is the most desirable. If this is the case then what we need to do is I think clear - put whatever balancing lead as close as possible to the fulcrum point. This would yield the best results in the soft zone and the hard zone. 2. Something other than the steepest slope is most desirable. This gives us a predicament. We then have to choose between biasing towards optimizing soft zone play or optimizing hard zone play. Or we have to come up with a new action design or balancing scheme that allows us to have a different slope in the soft zone and the hard zone. Another point to come out of this slope investigation - if it turns out that the steepest slope is most desirable, then this would indicate that we would get some return from reducing the inertia of the key itself. Some clever engineering of the keys might yield positive results. If it turns out that something other than the steepest slope is most desirable, this would indicate that the time and expense of doing this would probably be wasted. Also, on the next revision of your article perhaps you will include the idea of magnetic balancing and compare this to lead balancing. I think balancing with magnets should keep the slope of the line the same as the line for the unbalanced key but shift it to the left a bit. If the steepest slope is the most desirable, then this would appear to be a good way to go. If not, then perhaps leads would be better. Regards, Phil F Phillip Ford Piano Service & Restoration 1777 Yosemite Ave - 130 San Francisco, CA 94124
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