Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Question about Fandrich epoxy soundboard repair

William,
I enjoy discussing these types of things with you, as i find opposing view points very valuable. But i often only have time to address one or two points as my schedule is crazy busy.
Just because a timpani is round and the piano has another shape, does not mean the principle does not apply. With any shape there is a geographical point called the center of gravity, if a bridge goes over that point there will be a dead zone. The cut-off bar can make that happen.
The chladi "sand" will also avoid the cut-off bar, thus all that was done was reduce the size of the board.

I agree, the cut-off bar may just come down to personal preference of tone color. My choice is for getting as much depth in the tone as possible, hence my propensity for methods to accomplish that i.e. large boards, lightweight, long ribs, and techniques to assure that the bridge has maximum transfer of energy. So in my way of thinking why compare a small efficient board to a larger inefficient one? I would opt for making the larger board more efficient.

-chris

So are you talking about the center of gravity as in meaning the center of mass for an object? That is an often used meaning for center of gravity.

One can think of the cut off bar as being part of the rim, particularly if it is massive and bedded on the beams. Where a well-designed curved cut-off bar is implemented, the maximum number of ribs can center the bridge between the rim on one side and the cut-off bar on the other. In this circumstance, it seems to me that the center of mass will correspond to the location of the bridge, given that each side of the rib is of equal length and presumably equal mass. If the center of mass is at the activation point (in this case, the strings bearing down on the bridge), I think that might be preferable, because the forces are introduced so directly. Why would it be a dead zone? Explain that.


Yes, the chladni sand would congregate near the cut-off bar, in much the same manner as it congregates near the rim. These are stiff and massive terminations, so the sand won't move around them. But that's the whole point, to reflect the energy back into the panel. And very little energy goes past the cut-off bar to be lost, so that energy remains in the system as a gain.

A good soundboard system is designed to practice energy conservation at every place in the design. That is not mutually exclusive to either soundboards with or without cut-off bars. A great many gains would improve either system. We should remember that cut-off bars are used in rib-crowned and compression-crowned boards. Same for thick or thin, light or heavy.

Oops, wrong link to the Overs I-rib:

http://www.overspianos.com.au/iribbd1.html

This should get you there.

William, lots of interesting ideas and concepts on Overs page, and didn't stay by ideas also made (or makes?) pianos!

What happened, seems like the page is not updated in a very long time?

William, lots of interesting ideas and concepts on Overs page, and didn't stay by ideas also made (or makes?) pianos!

What happened, seems like the page is not updated in a very long time?

Clearly, Ron has not updated his web page in a very long time. I don't think he is making new pianos at present, but is still rebuilding.

I don't want to get into all the parameters that determine the tone and sustain of a soundboard, but I guarantee there are many. What I will say is that a rib-crowned board can be as light as a compression-crowned board, and can be so made with equivalent stiffness. Of course, there are many stiffnesses in a soundboard, i.e., various portions of the board will have measurable stiffness, and the stiffness won't be the same across the whole board. Soundboards are complex transducers with many subtleties.

Theoretically perhaps, but it practice not so much. And BTW, thanks for acknowledging the importance of weight. I am the only piano technician that has been an advocate for the importance of the effects of weight in a soundboard. If not true please show me the writings of others prior to 2017. I have documented how soundboards of the same size can vary in weight by 3- 5 pounds. I have a video showing 3 Baldwin R's and 1 Steinway M (same size boards) the lightest was 15.8 lbs and the heaviest was 18.7 pounds.

Here are couple rough rules of thumb I discovered. Maybe just Mathematical coincidences?

Lets take a 5'8" Grand:

1) Add a 1 it becomes 15.8 The weight of the soundboard (What it should be?).

2) Multiply by 2 it becomes 11.6 The number of ribs (Not quite 12, so 11 it is)

3) Total width of ribs should equal rib count(determined by size x 2) in CC boards.

Following these rough guidelines Steinways M's are 1 rib short with a rib count of 10. If you believe that SS suffer from dead octaves, this may be the root cause as the second section is not well supported (where the bridge has a bend) some would say.

There is a limit to the weight reduction, but my experience, too much weight is the main problem i observe.

Interesting side story:
When i built my Nuclear Fallout shelter I used the 1987 FEMA Plans (available as a free pdf online) It used 8x8x16 inch concrete blocks. The rooms are 8' x 16', the ceiling is 8" thick, and the rebar layout 8" x 16". More mathematical coincidences?

-chris

1) Why add a 1? Because.
My answer to the question. If you add 1 to 5' 8" (68 inches), it becomes 69 inches, or 5' 9".
What should the weight of soundboard be? Answer: Whatever Chris wants it to be. Why? Because.

2) Multiply by 2. What? I don't know. Why? Because. I will take a stab, though. 15.9 x 2 = 31.8. The number of ribs. 31 (Seems like a lot, though).

3) Total width of ribs = rib count, so 31 inches. Seems a bit on the light side.

It's not a coincidence, Chris. It's a conspiracy concocted by the Intergalactic Insect Brain Trust, cooked up in the restaurant at the end of the universe. Just head out to Alpha Centauri and go hard right, which I am certain you know how to do.

I wanted to donate my brain for them to study, but I was told that it just wasn't that interesting....

I can't imagine anyone thinking weight in a soundboard doesn't matter. Perhaps many people follow accepted rules of thumb that result in a reasonable weight. I have heard many people talk of soundboard impedance, which is a function of both weight and stiffness. If rib-crowned boards often aren't as light as CC boards, I suspect that's just because the person or people designing the board either didn't know how to make it lighter while maintaining stiffness, or thought the board's weight was OK, or just didn't think about it.
As to your other mathematical manipulations, I suspect they all would start to fall apart the further one goes from the 5'8" grand you use as an example. For example, if 5'8" grand should have a 15.8 pound soundboard, would it make sense for a 9' grand to have an 19 pound soundboard--that's a piano about 1.6 times as long, with a soundboard only 1.2 times as heavy? Should total rib width equal rib count? Maybe for CC boards, but perhaps not for RC boards, or maybe that number varies as a function of piano length. There are many little math tricks like those you mentioned that don't work over a wide range of variables, because the math relationships involved are not linear, but may be functions of squares, cubes, logs, etc.

As to your final example of the fallout shelter, yes, pure coincidence.

Dear Chris,

I recall several times in past years you called me to ask Questions about soundboards and I obliged you in spite of some of your nonsense. I know I instructed about the importance of soundboard weight. That however does not make me the first person to "discover" the importance of soundboard weight.

I certainly hope you can make an aQuaintance with the logical rules for inQuiry. You could contribute so much more if you could Quit the crazy.

Dear Ed,

We only had one conversation regarding soundboards back in 1998, and I remember our conversation well, because of the answer.


Ed said "Sorry it's Proprietary"

You NEVER talked about soundboard weight. Even in your simplistic class your description of bellywork was "It's easy as 1-2-3"

And never over the past few years did you once talk about soundboard weight in any of the other formats we debate on.

So no UN-TRUTHS please.


If soundboard weight was important, then all the Baldwin R boards i have done would weight the same.
As would all the Steinway boards, Weber boards, Chickering boards, Mason and Hamlin boards and all the others.

But they are not even close.


Thanks for not very much though.

-chris

Chris you are wrong.

The only thing I told you was proprietary was wound string scaling when you asked me to help you with your absurdly tall upright.

I talked about stiffness to weight elements from before you ever worked on pianos. And so have many, many other people.

Go gaslight someone else dude.

Dear Ed,
I scaled my Vertical Concert Grand all by myself. You told me a large upright like i described was impossible. So i don't understand why you want to take credit for something you had nothing to do with?

And we have never discussed soundboard related stuff, you must be talking about someone else.

-chris

It seems inconceivable that no piano maker or designer has talked about soundboard weight in the 300 years since Cristofori invented the piano, but Chris says he is the first so it must be true.

Chris, I think you would be really good at selling real estate and should consider running for high office.

William,
Then you should very easily be able to recite source material.

-chris

Chris,
I told you the action you were making for your super tall upright would not work without carbon fiber action parts because the wood scaled up to that size would make the inertia unmanageable.

You asked me to help you scale the wound section. I declined, because at that time I didn't want to instruct anyone what I was doing with wound strings.

You are calling me a liar. You should stop right now buddy.

Tell you what, Chris. I will meet the same standard of proof that you offer: I will claim that at least one piano builder/maker has talked/written about the weight of piano soundboards in the last 300 years, before you ever spoke about it. I will offer no evidence, as the claim is sufficient to make it true.

This standard surely reflects the times that we live in.

Dear Ed,

You Never gave me soundboard advice, your answer was always "It's Proprietary"
If I asked you about string scaling, "You declined to answer"
You said my action would only work with carbon fiber parts. I didn't use any.

So again thank you for not very much.


William,
I offered much proof, even made a video comparing soundboard weights of the same size board. One was 15lbs another was 18lbs.
Look at one of the first posts in this thread. Someone said that 400g of finish will not matter much. BTW, 400g is the weight of a violin. I say it matters because reducing weight makes a significant improvement in tone quality. I wish someone had published an article on the importance of soundboard weight because i would have gone in that direction much sooner.

You made a claim, i made a request to see the article, and you retorted with a dodge.
I'd really like to read the prior art that you were referring to.
-chris

Roy123,
Thank you for your insight regarding the exponential factor of my rough rules of thumb when it comes to 9' grands. You may be right. I just have not collected enough data on 9 footers to make a valuation like i could with smaller grands.

-chris