I'm not quite sure how one makes an action too powerful or even what that means. In my view an action would be too powerful when it breaks strings.
I think what was meant here is that an action can be too stiff.
Wood action components—most noticeably hammershanks—inherently have a certain amount of compliance. This compliance is something pianists are used to and adjust for as they play the piano.
Along with the compliance of the keys these are the two most significant factors in determining an action’s saturation level and, by extension, its ability to drive a piano to high levels of acoustic power. A piano action with flexible keys and hammershanks will reach saturation with only moderate key force. Steinway Ds from the 1960 (give or take a decade) are classic examples of this. Well before the playing level reached forte
those actions ran out of “power.” No matter how much harder the keys were pressed there was simply no more acoustical power to be had. They clearly demonstrated that piano actions can have too much compliance; i.e., they can be too flexible. In this case the chief culprit was the spectacularly inept Pratt, Read keyset that made the piano virtually unplayable as a concert instrument. It did, however, have the unintended benefit of teaching us at least the basics of piano action energy transfer.
Encouraged by our experience with these actions we just had to find out just where the opposite limits might be; if keys could be too flexible was it possible that they could also be too stiff? And, indeed, subsequent lab experiments using aluminum keys taught us that actions can also be too stiff. When they are too stiff the transfer of energy from the human finger to the hammer striking the strings is very fast and efficient but it is also very hard on the finger. No human pianist could play this piano for any length of time.
And this brings up Kamin’s
point which is, I think, that piano actions using carbon fiber hammershanks might be too stiff. I think, though, that this observation is based on acoustical concerns, not purely physical ones. The assumption seems to be that because carbon fiber composites are reputed to be very stiff then any hammer shank made of carbon fiber is going to be stiffer and therefore less than optimal at transferring energy from the wippen to the hammer when compared to traditional wood hammershanks. “Optimal” in this case being exactly identical to wood. Exactly which wood hammershank might be selected as the
standard might present a challenge since there is rather a lot of variability to choose from. In other words, there can be rather a lot of variability in wood-based hammershanks.
No matter. Wood is a natural material and is therefore perceived as inherently superior carbon fiber which, as we all know, is an artificial material. The bigger problem here, I think, is that wood is a familiar material. It is traditional. It is organic and comfortable. Carbon fiber, on the other hand, is new. It is exotic, unknown and unfamiliar. Most of us don’t really know much about it except for what we might have read about it in the popular press. We might know it is used in airplane wings or sailboats. From these sources we know that carbon fiber is incredibly stiff, right? Few of us have any hands-on practical experience with the stuff. We've never gone out to the shop and cut into a piece of carbon fiber. But we do know that it is inherently much stiffer than natural wood—everybody says so—so we can be certain that any hammershank made of carbon fiber is going to be much, much
stiffer than its wood counterpart. Right?
And now to burst this little fantasy—and please correct me if I’m wrong here—aren’t the current Wessel, Nickel & Gross hammershanks sized to approximate the average stiffness of their wood counterparts? Though without the variability common to the wood shanks? I’m not the most experienced Wessel, Nickel & Gross action installer here—and I’ve done no exhaustive testing—but based on my simple “feel” test they certainly “feel” about the same. And if one takes the trouble to weigh them it will quickly be seen that their weight is much more consistent.
Most of our fears about these new actions—be it the now almost traditional Kawai or the new Wessel, Nickel & Gross—are based partly on our popular, but incomplete, perceptions of the materials from which they are made and on our still-limited experience with them.
Any new material or technology is at an initial disadvantage when compared with a traditional material or technology. In the case of wood action components the industry has something over 300 years of experience with the stuff. Wood piano actions have evolved about as far as they are going to. We are not going to get much more precision out of the machinery. Nor would it do much to improve the performance of wood-based actions if we could. We’re not going to be able to do anything—at least not in practical terms—to improve their stability in varying climate conditions; wood is hygroscopic and there is nothing we’re going to be able to do about that. As well, we’re probably not going to be able to do anything to solve the variability inherent in felt bushings. And we’re probably not going to go down the road of plastic bushings in wood parts again; Steinway’s mishandling of the Teflon fiasco pretty much took care of that. So the wood-based piano action is now what is called “a mature technology.” It’s not going anywhere soon.
In contrast we’re still on a learning curve with actions made of alternate materials. In spite of Kawai’s now forty years of successful experience with them most pianists (and many piano technicians) have never encountered piano actions made of anything but wood. This is especially true with those whose experience is with and whose preference is for those instruments made in the 1800s and early 1900s. Here anything that smacks of “modern” is to be rejected simply because it is, well, modern. Specifically developments such as this are seen as attempts to draw even more power
out of an instrument that has already been pushed to levels of power that can, over the long term, be damaging to human hearing.
Anyone who has followed my work over the years knows that I have taken another path. For some decades now I’ve been preaching the benefits of toning down the harsh and strident sounds of pianos that have been pushed beyond what I see as their natural limits. In my work I stress the importance of reliable performance at the softest limits of pianissimo
. And it is for precisely this reason that I welcome the Wessel, Nickel & Gross action. At forte
levels of play even relatively large variations in the stiffness of materials are of little consequence. If they are extreme—which is rare—they might be noticed but for the most part the pianist just plays along at levels often exceeding action saturation. It is at pianissimo
where even slight variations is regulation consistency and materials consistency become critical. And it is here that I find the Wessel, Nickel & Gross action to be superior to any wood action I’ve ever used. (I would like to have one more hammershank tube with an even thinner wall, though, for those really light treble hammers I usually use.)
My advice to the critics is simply this: Don’t write these things off without a fair trial. You don’t have to give up your acoustical goals no matter what they are. I know some rebuilders who use these parts because they can get more power out the piano. I know others, myself included, who use them because they allow me to further expand the low end of the spectrum. In either case you will find improved consistency and stability.