>>Phil F wrote: This gives us a predicament. We then have to choose >>between biasing towards optimizing soft zone play or optimizing hard zone play. > >Bill Ballard wrote: The original choice is not between steep or shallow, >it is between choosing or not choosing. Like the original sin, it's not >which sin you'd pick, but whether you're going to be a "sinner". Or perhaps whether you're going to knowingly be a sinner. If this concept of soft zone and hard zone turns out to be important then by putting leads in the key in a somewhat arbitrary fashion we have already sinned, but we may not be aware of it. I suppose this study will be the fruit of the tree of knowledge. Once you partake thereof, you can't go back. >>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. > >A two-speed transmission, the second taking over after the breakpoint. >this whole system begins to resemble a torque converter. > >At 12:45 PM -0700 6/2/03, Phillip Ford wrote: >>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. > >Don't forget the rep and the shank. If you don't want mass in the key, you >don't need it in these either. I would like to see a real hammer out on >the business end of this action. Right. Some people tend to dismiss the whippens since changing their weight doesn't affect static touch weight very much. But they have inertia of their own and if we treat them as a mass applied to the key then they're also affecting the inertia of the key assembly. This may significantly affect the dynamic response of the action. The shanks are a little trickier, since it's not clear to me how their flexibility affects the tone. So while reducing their weight might be desirable, it might have to be done with specific stiffness parameters also taken into account. >>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. > >As soon as the optimal slop has been decided upon, designing the action >should be straight forward. > >At 12:45 PM -0700 6/2/03, Phillip Ford wrote: >>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. > >Here, here. Phil, let's both send him cookies. If this continues, the action may not be the only thing that has a weight problem. > I have two concerns with magnets. > >1.) As long as it is a Fazioli action being set up, one could trust that >the work being asked of the magnets moving conventional amounts of weight >in the action. With Mr. Chris's Aeolian grand, the magnets could also be >pressed into service on inertia problems which should have been dealt with >mechanically (ie., SWs, Fws, SBRs etc.) OK. But you could say the same thing about leads. >2.) I don't know how the coupling of parts operates during the return >stroke. This a complaint similar to that of helper springs, in that both >introduce a counterbalancing force with is separate from (and independent >of) the forces based on mass (gravity and inertia). During the down >stroke, the key is the driver and everything above it is coupled by >gravity and inertia. On the way back, the force of magnets (as does force >of springs) is working against the mass-based forces. BTW, both the helper >springs and the magnets grow weaker, the higher the hammer lifts, and >stronger as the key returns. As I see it, if I understand correctly the way the magnets work, then it would be similar to applying a helping force in the front of the key (sort of like the helping force from the weight of a lead) but without any additional mass or inertia being applied to the key. Since the inertia hasn't changed, the slope of the acceleration curve should be the same as for the unbalanced key. But less initial finger force would be needed to get it started. So the entire curve would be shifted to the left on Stephen's chart. It seems to me that the key would feel like an unbalanced key, only lighter. Whether this steep sloped curve is the desirable one will have to be determined by tests. It could be that pianists prefer more inertia, and the magnets aren't giving them that. Also, as you say, there is a curve for downward movement, and a curve for upward movement. Stephen's charts are only addressing downward movement. Perhaps we also need to be looking at upward movement. The upweight of a key and the way it works against the pianist's finger on the upward stroke is very important to the way the action feels. In this case he can make the key go down just as fast as the unbalanced key by applying the appropriate force, which would be less than that required for the unbalanced key. But if he reduces his finger pressure to what he normally would to let the key up, then the magnetically balanced key is not going to come back up as fast. Or another way to put it, if he raises his hand up at a certain velocity the magnetically balanced key will not put the same pressure on his finger as the unbalanced key. So, in this sense the magnetically balanced key would not feel like an unbalanced key, in spite of what I said earlier. The helper springs are reducing the weight of the action components being applied at the capstans. But they haven't reduced the mass or effective inertia of these components that the key 'sees'. This would seem to me to be another situation where you get help on slow playing but you get penalized on fast playing. And that seems like it would apply in both directions. Harder to accelerate the components up and for them to accelerate themselves back down. I'll give some thought to what that curve would look like, both on the downward key movement, and its return. Phil F Phillip Ford Piano Service & Restoration 1777 Yosemite Ave - 130 San Francisco, CA 94124
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