A few other observations and comments. I really don't think that there is much difference in tone output by virtue of RC&S versus CC if the designs and executions produce similar stiffness outcomes. In other words I don't think the piano will sound different because it has one or the other. The issues of predictability, controllability, longevity, warts and such I think are separate issues and certainly become part of the overall mix and decision making as to which way to go. But this contributes more in the details than the overall impression--at least that's my experience. At least when I'm comparing an RC&S board to what I would consider a successful CC board. That being said, clearly there are lots of options to consider when building an RC&S board that will impact the tonal impression. Rib scales and grain angle are two major factors. My own experience is that the number of ribs or the particular array doesn't really contribute to the overall impression assuming that the stiffness coefficients are the same. Whether there's more ribs that are smaller or fewer ribs that are larger doesn't impact the overall sound that much. It does make a difference in the number of soundboard resonances that occur. More and smaller ribs in a radial array will reduce the incidence of soundboard resonances. Some, like Darrell Fandrich, opt to reduce the soundboard resonances by the installation of riblets between the ribs. That seems to reduce the tonal differences where the strings attach to the bridge right over the ribs versus between them. At least, I believe, that's the reasoning and the claim. It's interesting to think about what it is that we are actually using to define the tonal character. We all tend to talk about sustain phase when referring to these boards but really the tonal impression, in my view, comes just as much (if not more) from the attack portion of the tonal envelope. Both are clearly important. The impact "thump" does serve a purpose and when I have heard pianos whose soundboard weighting reduces that thump to a minimum in favor of an enhanced development of upper partials and sustain there can be something lacking in the piano. Finding a balance between attack and sustain is always the goal whether it's in designing the soundboard or choosing a hammer (or both) and that balance, I believe, is what differentiates two particular pianos with the same string scale (since the string scale itself is really at the heart of what defines the differences). But since we're talking about RC&S versus CC and if the goal was to create a similar tonal impression but with a design that was, say, more predictable, controllable, longer lasting and without the warts, then attention should be paid to the attack phase as well and what the particular RC&S design yields. In this case, rib scales and grain angles are at the heart of what needs to be considered. There's no reason that I can see (or hear) that you can't create in a Steinway, for example, a classic Steinway sound using RC&S methods. It just requires a careful consideration of the factors (rib scale, grain angle, accompanying downbearing settings--and hammer selection, of course) that contribute and clearly defining your goal. The beauty of the RC&S method is that creating variations in designs yields results in which the specific contribution of the inputs are much more evident. That being said, there's still a lot of work to do. David Love www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of jimialeggio Sent: Wednesday, July 14, 2010 6:23 AM To: pianotech Subject: [pianotech] soundboard grain angle vs "faux"stiffness I've been thinking a bit about how the calculated rib scale allows you to design a spring with known stiffness, and have setup my spreadsheets and belly experiments to predict and adjust this quantifiable stiffness/flexibility (spring). As has been mentioned, there are other parameters such as back scale and grain angle, panel tapering or not tapering which also effect "stiffness". I put "stiffness" in quotes because ribs design targets and creates a spring while these other parameters, backscale etc either restrict or avoid restricting that spring...they don,t create spring. They are often referred to as having "stiffening" qualities but I'm thinking that there is a structural and tonal distinction between stiffening as the result of spring rate of a rib and "stiffening" as the result of limiting movement of the rib spring. David Love, it sounds like you've played around with various grain angles on calculated rib boards. Have you experimented with the traditional 45ish degrees, ie somewhat parallel to the long bridge, board angle? Most of the rc&s boards I seen or hear about assume that the slightly greater 50-55 to more is an improvement, while some push 70deg. It seems as if the tenor and bass would appreciate the near full crossgrain effect of grain parallel to the tenor in the long bridge. As in most belly issues, I suspect that the tradeoff was made to help out the treble, ie keep the rib weight down in killer octave by "stiffening" the board in that area. Are there any calculated string load/rib scale folks working with low grain angles? Jim I -- Jim Ialeggio grandpianosolutions.com 978- 425-9026 Shirley, MA
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