Have at it. Long wind always welcome. David Love www.davidlovepianos.com -----Original Message----- From: Nicholas Gravagne <ngravagne at gmail.com> Sender: pianotech-bounces at ptg.org Date: Wed, 14 Jul 2010 16:21:48 To: <pianotech at ptg.org> Reply-To: pianotech at ptg.org Subject: Re: [pianotech] soundboard grain angle vs "faux"stiffness Nice posts, David, and some of the more balanced on the subject. I hope to respond to some of your observations soon, as well as post a concise (hopefully, I do get long-winded) separate piece on the major points of impedance, as this is really the overriding principle involved. Thanks Nick On Wed, Jul 14, 2010 at 2:52 PM, David Love <davidlovepianos at comcast.net>wrote: > 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 > > -- Nick Gravagne, RPT AST Mechanical Engineering -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100715/f20cdc34/attachment.htm>
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