To develop a bit more what I commented on previously, I've done both RC&S and retained original CC boards both with modified front duplexes and without. Similarly I have done (or had done) RC&S boards with modified backscales and without, with modified and radial rib arrays and with original rib positions, with bass floats and without bass floats, with transition bridges and without transition bridges (and with various styles), and with treble fish and without them, and with varying degrees of changed grain angle so that I could see for myself what contributions each of those changes make. I have come to some conclusions but I'm not really ready to share everything yet as the jury is still out on some things. However, with respect to modified strike lines I can say that the RC&S board generally, no matter what the other changes might or might not be, seems not to require changing the strike line the same way it does with the CC pianos that I've encountered. The fact that Dale has found a consistent reason to go so far as to teach a class on finding the "sweet spot" suggests to me that a compensation for inadequate tonal production is often necessary on that style piano (cc) and that it's most evident in the killer octave (not surprisingly since the problems of compression crowning seem to exhibit themselves most in that area). I don't have an explanation as to why the biggest modifications of the strike line seems to be on Steinway B's and to a slightly lesser extent Steinway Ds except to say that it probably has something to do with the particular dimensions including rib layout and soundboard shape and width on those models. Smaller models and pianos built by other manufacturers may require a change in the strike line in the upper sections, a little in or a little out, but I haven't found them to be nearly as idiosyncratic as those two models with a curved line. I've not really collected any real data on the differences in modified strike line requirements between makes and models, maybe Dale has and can offer some input. Suffice it to say that the modified strike line seems to be a requirement of cc boards and not pure RC&S boards, at least in my experience. One other comment, the RC&S boards that I'm doing are all calculated in terms of stiffness in each section of the piano (Ron has touched on that method in other threads on the subject) so there's no by the seat of the pants reckoning in terms of the rib dimensions. Pianos that are hybrid designs or where the stiffness of the board in different areas is done more by feel aren't part of my experience and are probably not good candidates for drawing conclusions from since the stiffness in each section can't be quantified in the same way. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of William Truitt Sent: Monday, February 08, 2010 3:44 AM To: pianotech at ptg.org Subject: Re: [pianotech] Hammer strike line. Was-----Yamaha Hammer Suggestion HI Ron: If David's pianos had retained the original front duplexes, then that would allow him to isolate the phenomena observed a little more. The changed front duplexes are not offered here as an alternative explanation per se. Pertinent to this discussion, I am noting only that the changed front duplexes muddy the waters of our observations, in that we have another change to contend with, when we would prefer to isolate the observed phenomena as much as possible. Come to think of it, I know that you replace the short back scale string lengths inherent to the Steinway rear duplexing with a vertical hitch pin that allows a longer back scale length, which I believe has a positive effect on the amount of energy that the system retains and also assists in the improvements that you observe in the killer octave area. Doesn't mean you are wrong, only that the waters are muddied still a little more. Those changes are not taking place in the soundboard per se, but as part of a system. David can answer this question perhaps. I think he retains the rear duplexes on some of his R, C, & S designs, and perhaps he has done R, C, & S boards where both the front and rear duplexes are retained, and not felt the need to move the strike line. If so, his observations have the luxury of being more isolated from other phenomena than yours. And now, if I may throw my last monkey wrench into the gears. I had the great pleasure of attending the 2006 National in Rochester and spending a lot of time in the Rebuilder's Showcase. I was very favorably impressed with the two R, C, & S pianos there from the Rons - Overs and Nossaman. And I was impressed by all the other pianos there, which rounded out the continuum of soundboard construction methods, with CC boards and rib crowned boards. While every piano was different and reflected the personality of the rebuilder, the unifying element was the very high quality of these instruments. They all were really wonderful instruments. I could not resist the impression that a strong part of the success of each was the very high quality of workmanship, the attention to every detail and the superb execution of the work. Which points to the difficulty that we always seem to face in our work, the significant difficulty of isolating the things we observe from other causal agents. How many of us have made a change in a particular area and had a positive result, come to the belief that our change was the cause of the improvement, only to have that not borne out as a consistent improvement as we continued the change in subsequent pianos? Still, we all have to stumble along. If the change we make seems to make an improvement that is consistent, we keep it in our subsequent work. And you have offered your own observation that it is consistent from board to board in the killer octave area, and obviates the need to move the strike line. That's good enough for now and as much as we can do anyway. Will -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Ron Nossaman Sent: Sunday, February 07, 2010 11:17 PM To: pianotech at ptg.org Subject: Re: [pianotech] Hammer strike line. Was-----Yamaha Hammer Suggestion William Truitt wrote: > A little curve ball question to go along with this: Aren’t you and > Ron and a few others getting rid of the front duplexes and replacing in > with a  single bar with a shorter length between the v bar and the > string rest? There won’t be the kind of energy losses with that > configuration as there are with the duplexes, which would also > contribute to an improvement in tone in the killer section. Quite possibly. A plausible contender. The next question would be to David L as to whether the pianos in which he found it unnecessary to bend the strike line had original duplex scales or not. Mine did not. Good question. Ron N
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