> All I was saying was that my spreadsheet works with the other
> features in the designs that I do and if those features were to
> change so might the way in which the rib scale is calculated. Of
> course any change in the number of ribs or the length of the ribs
> will change their dimensions. That's a given. I'm talking about the
> criteria that is used to determine how much the rib scale should
> contribute to the support when other features might change just what
> the ribs need to contribute. For example:
>
> I understand the reasoning for the radial rib pattern and where it
> comes from. However, it also places the ribs closer together on one
> side (bent side) and farther apart on the other. How does that
> affect the stiffness of the assembly or how does one side of the
> assembly being stiffer than the other affect the tonal response or,
> more to the point, how would it affect my rib scale design. Can't
> say.
That's right, you can't say. You can't say if it matters or if it
doesn't. When you or anyone else can tell by listening if the piano has
a radial rib layout, it will then be a concern. Until then, it's
something you don't do because you don't know if it matters tonally. I
don't either, but I accept Conklin's research as to resonance control,
and if I can't detect a tonal penalty any more than anyone else can,
I'll take the benefit offered without hinting at mysterious possible
consequences that are undetectable. What's the point of doing that? Why
can't we offer practical and beneficial alternatives rather than vague
hints of doom for deviating from your approach. This is exactly why I
advocate that people read up on the science and do their own thinking
instead of following others' advice without explanation. This is why I
also offer reasons behind why I do things, whenever I can, to give them
some place to start.
> I think you're being a bit defensive on the rib radii.
No, I saw yet another vague caution about radical construction, and
offered my reasons for doing what I do. Again, reasons. When someone can
recite rib radii from the sound produced from the piano, I'll believe
that it's critical. Until then, I'll do what works for me for the
reasons I've given, and others now know my reasons too, so they can
decide for themselves what is right and proper.
> I wasn't
> being critical of that decision to go 4-9M But making the rib with a
> tighter radius probably makes the assembly stiffer and I don't have a
> handle how that would change my rib design exactly.
No, it doesn't make the assembly stiffer. And no, in spite of your
continual hammering at it, my soundboards aren't "overly" stiff. As I
have pointed out (reasons) my rib scales are heavier than yours because
I keep the panel compression much lower than you do in your boards.
Speaking of which, Ron Overs makes the stiffest soundboard assembly I've
ever seen, and a pretty damned fine sounding piano. So I don't see the
point of your repeated warnings about overly stiff soundboards except
possibly hinting that everyone else does it wrong except you. Have you
heard one of Ron Overs' pianos? Have you heard one of mine? I haven't
heard one of yours, so I can't say how you're doing, but Ron O is doing
just fine.
> From my own
> experience and experiments I think it would though. Additionally,
> how does making the ribs from a laminate impact the performance.
It certainly makes the MOE more uniformly predictable. More vague hints
of doom? Again, when you can tell if a piano has laminated ribs by
listening to it, that will answer the question.
> Again, I don't know the answer to that. I'd have to look into it
> further.
Further?
> Cutoff bars that are placed to remove enough area from the bass
> corner and the area behind the bridge to essentially place the bridge
> in the middle (for the most part) of the panel while maintaining a
> standard 8 mm panel thickness create a stiffer panel and one with
> less overall mass.
Overall assembly stiffness is controlled mostly by the rib scale.
Shorter ribs mean you can make them less stiff and they will still do
the same job as a longer stiffer rib. You should know that. I consider
less overall mass in the assembly a good thing. Mass distribution is
something to look at though. Less mass in the bass, and more in the
treble works quite well.
> When you combine that with no panel thinning at
> the perimeter (which at last reporting you didn't do) then you have
> again something that reacts differently--it will effectively be
> stiffer again. How that would impact my rib design considerations I
> can't say exactly except that it would likely push it in yet a
> lighter direction.
I don't typically thin 8mm panels. Why is that so offensive to you when
you haven't heard my results?
> Some people I've spoken to who are making these designs and having
> them come out stiffer than expected are backing off on the
> downbearing.
I'm not. Trot these people out and let's talk to them to find out what
they are really doing. Some people are making really nasty sounding RC
boards too. If they would discuss it honestly, we could probably learn why.
> I don't know if that's the right thing to do or not.
> Some of the problems that we have heard reported on this list
> (nasally sounding low tenor comes to mind) are a function of too much
> stiffness, in my opinion.
The 19% break% in the low tenor scaling has nothing to do with it, I
guess. How did panel stiffness become your universal fault for all piano
tonal problems? This never did make sense, and it's getting way out in
left field here.
> So my point is that my spreadsheet and the way I use it takes into
> consideration the features that accompany it. If you change those
> features you may well have to reconsider the criteria that you use to
> calculate the rib scale.
That's how I took it. I certainly know of no spreadsheet that designs
scales, strings or ribs, at the push of a button, but it does need to
give you meaningful output.
> That's all, I wouldn't read anything more
> into that statement than there is, unless you want to, of course.
> You may have the last word. I expect you will.
I have no use for the last word, but I do try to make sense.
Ron N
Original Message------
All I was saying was that my spreadsheet works with the other features in the designs that I do and if those features were to change so might the way in which the rib scale is calculated. Of course any change in the number of ribs or the length of the ribs will change their dimensions. That's a given. I'm talking about the criteria that is used to determine how much the rib scale should contribute to the support when other features might change just what the ribs need to contribute. For example:
I understand the reasoning for the radial rib pattern and where it comes from. However, it also places the ribs closer together on one side (bent side) and farther apart on the other. How does that affect the stiffness of the assembly or how does one side of the assembly being stiffer than the other affect the tonal response or, more to the point, how would it affect my rib scale design. Can't say.
I think you're being a bit defensive on the rib radii. I wasn't being critical of that decision to go 4-9M But making the rib with a tighter radius probably makes the assembly stiffer and I don't have a handle how that would change my rib design exactly. From my own experience and experiments I think it would though. Additionally, how does making the ribs from a laminate impact the performance. Again, I don't know the answer to that. I'd have to look into it further.
Cutoff bars that are placed to remove enough area from the bass corner and the area behind the bridge to essentially place the bridge in the middle (for the most part) of the panel while maintaining a standard 8 mm panel thickness create a stiffer panel and one with less overall mass. When you combine that with no panel thinning at the perimeter (which at last reporting you didn't do) then you have again something that reacts differently--it will effectively be stiffer again. How that would impact my rib design considerations I can't say exactly except that it would likely push it in yet a lighter direction.
Some people I've spoken to who are making these designs and having them come out stiffer than expected are backing off on the downbearing. I don't know if that's the right thing to do or not. Some of the problems that we have heard reported on this list (nasally sounding low tenor comes to mind) are a function of too much stiffness, in my opinion. Too stiff or not stiff enough? Well if I had to err on one side I would certainly choose too stiff than not stiff enough but it's not without consequences.
When all is said and done with those features I outlined above you will likely have an assembly with less mass and generally stiffer and has all the performance characteristics that go with that. My own personal experience demonstrates that employing all of these features certainly "works", the sound is good,though the result is different (and no, not all designs that don't use these features have killer octave problems or short term soundboard failure issues), but I can't say that I prefer it and I guess that's the bottom line.
So my point is that my spreadsheet and the way I use it takes into consideration the features that accompany it. If you change those features you may well have to reconsider the criteria that you use to calculate the rib scale. That's all, I wouldn't read anything more into that statement than there is, unless you want to, of course. You may have the last word. I expect you will.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
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