Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum 112 year old Steinway repaired soundboard a worry?

Hmm. Have you ever considered that you might actually be wrong and that I, along with most piano researchers and rebuilders—and along with the various wood technologists—who have studied the subject might be right?

Your analogies make no sense. Compression-crowned soundboards lose their crown, and a certain amount of stiffness, due to perpendicular-to-grain, time-dependent compression set within the soundboard panel. An old house withstanding an earthquake is not subject to perpendicular-to-grain, time-dependent compression-set; after all, how long does an earthquake last? (Time-dependent compression-set is a factor in why those old houses have “settled” over the years, however.) Introducing ships masts and bent harpsichord rims into the discussion further illustrates your lack of understanding about how the compression-crowned soundboard actually works.

I have repeatedly explained these phenomena and have provided various technical references explaining and supporting my explanations. So, please, don’t tell me I’m unwilling to examine the physics of my theories. I dismiss my critics only when they are thick-headed and simply wrong.

ddf

Huh? I'm not sure I understand this comment.

Remember there are two distinctly different systems in common use and the explanation for how they work is a little different for each. (As well, there is a certain amount of overlap between the two in many pianos.)

In the pure compression-crowned system the ribs actually resist the formation of crown. When string bearing is applied and the assembly is forced “down”—flat—the compression within the soundboard panel increases slightly resisting that force. The ribs actually relax somewhat—remember, they started out flat and they would like to return to that flat state.

Eventually when the initial perpendicular-to-grain panel compression has dissipated due to long-term compression-set the assembly will be back to its flat condition; the perpendicular-to-grain compression will be gone and there is no longer any stress interface between the tops of the ribs and the bottom of the soundboard panel.

In this state if the relative humidity goes high enough to develop some amount of perpendicular-to-grain compression within the soundboard panel then it will again belly up. By this time the wood fibers within the soundboard panel will have established equilibrium in a moderately compressed state so the amount of crown that be induced by this change in moisture content will be nominal, but there will be some.

If the ribs were originally machined to a crown they are normally in a relaxed state before any string down force is applied. As is the soundboard panel, assuming a pure rib-crowned system. As string down force presses the assembly down the ribs act like structural beams with the top developing some compression stress and the bottom developing some tensile stress. The soundboard panel will also develop some amount of perpendicular-to-grain compression but it will be a relatively small amount.



I don’t understand the question. What do you mean by, “how much is the crown likely to increase from say 0.001” in its dry state?”

ddf

I'm sorry that was shorthand for what happens to the forces at play when the moisture content of the wood goes up in high humidity?

The idea was that if the ribs and the down-bearing were to have equal and opposite effects on the board when it is flat and dry then it would be in unstable equilibrium and could move in either direction. The down-bearing might even cause it to belly out to a reverse crown if the increase in moisture had sufficient effect the properties of the wood. In practice, presumably, the ribs will be a bit more substantial than that and, as you point out, their presence also ensures the board will expand into a positive crown.

Thanks to your exposition on compression and rib crowned systems, I, for one, understand what happens much better than before.


This came from a post earlier today, which I may have misunderstood, where you wrote:


Since we had been talking about a flat board I took the lower figure of 0.001" as being the lower end of reality. I was asking about the the dimensional change in the crown in Arkansas and, aside from pitch, do swings of temperature and humidity have a noticeable effect on tone?

Ah…it’s impossible to tell what effect changes in relative humidity, and subsequent changes in wood moisture content, will have on actual soundboard crown. There are simply too many variables. Among them the strength characteristic of the specific wood involved, the design of the soundboard assembly, string bearing, etc. As well, soundboard assemblies do not necessarily crown and decrown (is that a new word?) in a uniform manner; they distort. That is, as a soundboard panel takes on moisture and attempts to force a crown into a system that is loaded with string bearing, the bridge may not move much but the areas on either side of the bridge might well belly up some. In cross-section this looks like a very wide, but shallow, “m.”

Changes in moisture content can have an effect on piano tone. Aside from the influence of water vapor on wool piano hammers, the assembly stiffness of a soundboard structure changes with variations in the wood’s moisture content. A very dry soundboard assembly will have less panel compression and less stiffness while the same soundboard assembly will have somewhat more panel compress and more stiffness when it has absorbed more water vapor during humid weather. In areas where climate swings are extreme it is not unusual for pianists and technicians to notice these changes. Some pianos exhibit virtually no discernible change while others are more obvious about it. I suspect it has to do with the thickness of the soundboard panel but it’s not something I’ve studied.

(The figure, 0.001”, did not refer to an amount of crown but to the hypothetical distance the ends of the ribs might want to move in if they were not restrained by the rim and if the wood from which the ribs were made exhibited no tensile strain at all when subjected to tensile stress.)

ddf

Having worked in construction and remodeling, I can tell you that Douglas fir gets harder and stiffer with age. Nail a new sole plate to an old floor, do some hand sawing, and you'll see the difference. Same for spruce?

If there's any relevance to soundboards, it might be the behaviour of joists and rafters. Usually they last just fine, and retain their original shape and strength. Sometimes, if they were a little too small for the load to begin with, you'll see them sagging in the middle. I've seen tile roofs on 2x4's 24" O.C. that got a definite sag after 80 years, while the joists stayed fine.

Bottom line, my guess is that it'll vary from piano to piano. Some soundboards may fail in 80 years, others may go a few hundred, depending on the material and the load.

About 4 years ago I bought a restored 1905 Steinway "A" art case piano. Most parts replaced except the soundboard. Sounded good, huge improvement over my 1908 "M" that definitely needed a total rebuild. But as I had the opportunity to play other fine pianos I realized that it was lacking in several aspects of its sound.

After deliberating for about two years (I liked the idea of keeping the piano as original as possible), and trying various methods to improve what I had, I finally succumed and went for the installation of a new soundboard. I just received it back from Cunningham Piano Company. It made a world of difference! If you buy this piano I'll bet you'll be looking at replacing the board in a few years.

I don't want to get into the technical aspects, just the results. Truly a transformation. Can't say enough about the quality of the work done by Cunningham under the sterwarship of Rich Galassini. I'll post more about it later, after I've lived with it for awhile and can share other reactions.

Almost all of that DF was at or near saturation moisture content, 28 percent EMC or better, when it was bought and made into a house originally. That is why you sometimes get wet from the spray when you're driving in those nails. Drying out for some months would make it both harder and stiffer than a piece that was saturated at initial construction. Take a hard, older piece and float it in the holding pond for a couple weeks and it will get more pliable and softer again. It will also weigh a bunch more.

Or in six months.

I often hear about how some woods—Douglas fir, in this example—get harder and stiffer with age. Always this assertion is based on anecdotal observation; never by actual test. As far as I have been able to determine, there is no scientific evidence that supports this belief. To be sure, if wood is protected from adverse climate conditions and from excessive heat exposure and from abnormal stresses—whether short-term or long-term—that cause irreversible damage, it can maintain something close to its initial strength characteristics for decades, if not centuries. According to The Wood Handbook—Chapter 5 Mechanical Properties of Wood:

Notice there is no mention of gains in durability and strength, only losses.

There are many explanations for the belief that wood gets harder and/or stiffer with age. One of them—the variation in moisture content—Dale has already mentioned. Another is simply that we don’t know what the strength was in that piece of old wood back when it was first cut and assembled into that house. We do know that it was probably old-growth timber. We also know that second-growth and plantation-growth timber does not produce wood that is as strong as the original old-growth wood. There are several other environmental factors that can also affect both the long-term and the short-term strength characteristics of wood.

ddf

Del,

A bit off topic, but I would like to know
at what point will a piano manufacturer put serious R&D dollars into developing a composite soundboard material that is reasonably impervious to humidity, has a low temperature coefficient, and actually resembles wood in it's tonal qualities. I would think the supply problem and inconsistencies in what can be supplied would eventually force bbuilders to come up with something.

As soon as they start loosing sales for the lack....

ddf

Done - Steingraeber has it now. During last year's Piano World piano tour we visited the factory. There were four indentical pinaos except one had a composite soundboard. About 20 of us tried them, no one could say with certainty which had the composite board.

Thanks Dell, all extremely interesting and, as I read it, all part of the argument for laminated/composite soundboards in the future. But that is definitely OT and I think it has been covered before.

I'd be happy with a piano with a 112 year old soundboard if it stood out against other pianos I might buy and if I knew who had restored it.

PS Saw Daifanshi's post about composite soundboards after posting.

This is good news. Maybe the biggest thing to happen to pianos since the Erard action.

But it troubles me a bit that it takes one of the "microbrews" of piano manufacturing to do this. Why big builders like Yamaha, Kawai, or Samick hasn't jumped in with a composite board means they've done their cost analysis and wood is still cheaper. Since it is obviously not a lack of technical resources.

Not necessarily, see this link about the inception of this soundboard.

If you have the desire and money you can do anything. I mean Yamaha or Kawai could just outright buy the Steingraeber company just for their soundboard. Or hire the entire team that did that soundboard. It might be expensive, but it's all about money.

The difficulties are not technical, they are societal and marketing. Right now Steingraeber is the only company making and selling a piano with a composite soundboard panel. And it ain’t cheap.

This is not the only way to achieve essentially the same results, however. Laminated soundboard panels give very similar results—good voice, better stability, resistance to cracking, etc.—at far less cost. It’s a well-developed and proven technology that is available immediately. The problem is not with making the things and it is not with market acceptance among the actual buyers. It is with the marketing and sales organizations in between. So many of them have been attacking and criticizing the technology for so long they now find themselves in a quandary; how can they admit they might have been wrong about these things without loosing face?

ddf

Del,

In a laminate constructed soundboard, are the layers of wood arranged so that each additional layer has it's grain perpendicular to the previous layer? Or something else? And how many layers can there be in a typical soundboard?

You've mentioned in this thread that soundboard compression over age is primarily in the cross grain direction. I can see how it is nearly impossible to prevent this in a single layer soundboard. But does a laminated soundboard with perpendicular oriented layers mitigate the forces involved in the compression to any appreciable degree? Or since the layers are thinner, there is no net improvement?

Cross-banded lamination has its long-term pitfalls, as well. The constant fight between two different rates of expansion in the layers tends to break down the glue joints. This same stress tends to tear at the wood fibers and challenges the glue itself. Some of our best glues may still have a definite life span chemically. On some of these glues, who knows how long they can last.

Some of the earliest laminated boards were not intended to be high end products (a Kimball studio, for example). Now, we have much more serious attempts. What we don't have are examples of laminated, high-end boards which have passed that 60-year range which others on this forum have mentioned previously as being the point at which many sound boards begin to "lose it."

It's been done. The question with laminated boards is, "How long can it stay done?"

Well, I've got a client with a 1968 Story & Clark console with a laminated board that's functioning perfectly after 44 years - not an insignificant amount of time. And it sounds good! So good, in fact, that the piano warranted a Dampp-Chaser, hammer reshaping and a full regulation. I can't see or hear any degradation whatsoever, and the piano was basically neglected for 20 years with no servicing done to it. It has responded beautifully to all the work, and has very good tonal characteristics and sustain, even with the somewhat crappy original hammers.

I think that I have serviced some Story & Clark of roughly that vintage, but the hammers and strings (false beats) were so bad that I couldn't really judge the sound board. Was that the laminated mahogany version?