I don't know if I want to go through the entire discussion we just had again. Many of the questions and premises that you mention below I've covered already in the voicing with lacquer discussion. A rereading of that to clarify might be in order but I'll mention a few things.
The "a" in F = ma is limited by the fact that the action must regulate within a fairly narrow range, say a distance ratio of 5.5 - 5.9.
Mass of the hammer, on the other hand, is not so limited. While the tendency is to link higher mass with lower ratios, we're not forced to do that. If you do the Stanwood math on weight and balance using certain balance weight targets, front weight percentages of maximum, action ratios (SWR in his case) and plug in number you see that there is quite a range of possibilities for strike weight, for example on note #1, Ao:
BW = 36, SWR = 5.9, FW% of max = 75, yields a SW of 9.8
BW = 42, SWR = 5.5, FW% of max = 95, yields a SW of 13.1
Standard wippen SW and a Key Ratio of about 2:1, or .5 in Stanwood terms (my numbers may differ slightly from DS's but that's the basic idea).
Both of those fall within the range of "normal". So the mass of the hammer can vary considerably even if I wouldn't necessarily target the extremes.
Heavier hammers are not our reality. That's like saying the only store in town only sells TV dinners so I shall assess the range of my cuisine experiences as either fried chicken, turkey and stuffing, or Salisbury steak (though I did like those turkey TV dinners when I was a kid). We do have other choices and can order hammers to our own specification if we know what to order. A hammer that is a close match to the 1920's Steinway hammers is available if you know how to order it (not from Steinway). The specifications of the hammer are critical and each of the attributes that I outlined in several previous posts on this subject must be considered in balance with each other. It is not currently a "stock" hammer, your are correct. But it should be and may be in the near future.
More mass in hammers is a trend, I acknowledge, but it's not just more mass that is at issue, it's where you put the mass, in what part of the scale. In the lower part of the piano it can be a benefit, in the upper part of the piano it is a detriment. Depending on the soundboard impedance it can be either a benefit or a detriment. A lightweight hammer won't likely sound good on a Ron Overs concert grand. But the hammer that does drive that system won't sound good on a Steinway M.
I can't speak for what David Stanwood or Dale Erwin advocate or if what you report about what they do or say is even true. If it is something that they said I would ask several questions, on what piano did you increase the mass (scale, soundboard impedance characteristics are very important), what was the starting point, where did you end up, what do you mean by better, to name a few? More mass in a hammer sounds better is a meaningless statement on its own.
I have put clips on hammer shanks for customers who wanted more weight. I'm thinking of one piano teacher I have who has a Hamburg Steinway A. We put on clips to increase the weight for her quite a bit. The piano sounds ghastly. It is louder, and horrible. She now plays it with the lid closed, completely closed. Her colleagues, of whom several are customers of mine, ask me when I will do something about her awful piano. Is that what you mean by better? Louder? It is that.
The best fix would be to remove the clips, reduce the mass and bring the energy input back to some range that the piano can handle. But she wanted to save money and not remove leads from the keys and rebalance. Finally, I have talked her into taking off the clips and removing some lead. We'll see if she actually follows through. The piano sounded fine before.
I would probably dispute what you refer to as "Dale Erwin's notion of action geometry". I know Dale quite well and while we may approach these things differently I think his notion would be if you put on a heavier hammer then you better reduce the action ratio. He would be correct on that account. The choice of hammer mass for tone is a different matter. I can't speak for what Dale does on each piano because I don't see every piano that he does. However, I have seen some pianos that use 16 lb Ronsen hammers, something he does use at least at times, which are very heavy through the treble as they are typically delivered. I recently took a set of Ronsen 16 lb Weickert hammer off of a Steinway B (not Dale's project) on which the strike weight at note 88 was 6.9 grams--that's massive to put things in perspective. I also recently removed a set of original Steinway hammers from a B of the same vintage, strike weight at note 88 was 3.7 grams. SW includes the shank weight of course. That's more than 3 grams difference, more than double the total weight of the hammer on the original. Needless to say, the clarity and power, defined as energy left in the string, by the original was like night and day. The 6.7 gram hammer, filled with lacquer btw, was muddied and without any appreciable string energy at all. It delivered quite a whumpy splat at impact, but I wouldn't call that better, or even tone. More mass and more bulk on a hammer that is low on density is asking for trouble, or lacquer, and then it's asking for a different kind of trouble. That seems obvious to me. If you want a lower density hammer then you have to match it with other attributes that make sense: lower profile, lower weight, in particular.
That was generally representative of that entire set, btw. I replaced the set with the same hammer (Ronsen Weickert), at least two grams lighter in every part of the piano with a much trimmer profile (see my previous posts to know what I mean by profile) and the piano delivered more power, with greater clarity, better partial development, better tone. Just my opinion? The customer who had just bought that piano was on the verge of selling it, didn't play it and was quite depressed about it (not a small purchase). Of course there were weight problems too, as you can imagine. Well, she's keeping it and you can't get her away from it (sounds like the Checker's speech). More mass is better??? I don't think so.
Ed McMorrow has for some time advocated for very light hammers and, in the past, has a method of lacquering them as well which is somewhat uniquely his. On several fronts that's not what I'm advocating. You can go too light (especially in the lower part of the piano) and I don't care for lacquer. It's damaging to the hammer and not necessary if you order the hammers properly dimensioned for the place in the scale where they fall. Again, something I covered in the lacquer posts.
I don't know what drives what, honestly. Although what continues to perpetuate it is our complacence about asking for what we want and need. Part of that is, of course, knowing what we want, admittedly not an easy task. We take the medications that the pharmaceutical sales people tell us will work. We donât ask, they must know best, after all, they are making the stuff--and selling it too, I might add.
You wrote: "I would tend to argue against the notion that denser or stiffer hammers should be voiced in a "layered gradient" as the whole story of treatment. That is certainly one approach and a philosophy that many have espoused, but I think it is a mistaken one, that deep shoulder treatment should be the basis, then a little surface gradient for attack sound at lower volumes."
This is a bigger subject and speaks to my concept of Structural Voicing, but I just completely disagree with you. Re the "layered gradient" I didn't say this was the "whole story" but it is a major part of it. Also, be aware that I have repeatedly discussed that there are differences in how hammers that have a lot of tension versus ones that don't react. My voicing experiences over several decades continue to reinforce that. Controlling loudness is a primary function of voicing--loudness when you want it and not when you don't want it. I believe the hammer should gain density as it compresses, progressively in a controlled way. That not only gives you stepwise dynamics but progressive development of timbral dynamics.
You are advocating the old notion of the iron fist in the velvet glove. A model that was used for decades but is incomplete as a mental construct, if you ask me. Unfortunately, once you get past the velvet it is simply an iron fist. Surface voicing, even if you prepare it with some shoulder needling, will not yield anything progressive. Moreover, shoulder needling is often useless on certain hammers whose inner structure often never allows anything to move as low as the lower shoulder. Those hammers, characterized by a lack of tension, must be addressed higher in the shoulder, even very near the crow, to introduce greater flexibility at the crown when force is applied in the direction of the molding. A *heavily* lacquered hammer is the epitome of that in which low shoulder needling is of no consequence whatsoever and any needle treatment must go directly into or alongside the strike point.
I prefer a dynamic range that is progressive, not off and then suddenly on. Your concept may work well in a concert venue where you *may* need to climb the dynamic ladder more quickly. But for 99.9% of everything else, a progressive dynamic range accompanied by a progressive development of more and more partials is the goal and, in my view, is a critical characteristic of quality tone and a quality voicing job that will deliver more dynamic variety and timbral dynamic variety as well. Of course, this is a discussion of defining esthetics and is difficult but probably necessary at some point. Unless we have similar tonal goals then trying to make a decision about what we need to support that is fairly meaningless. Personally, I think a consensus is achievable in spite of differences in taste. If that's not the case, then we may have to agree to disagree.
So to your last question, what mass matches what impedance level? It's an incomplete question. It's not only mass. As I've said over and over on previous posts, there are several dimensions on which a hammer can be measured: tension, density, weight, profile, being the main ones. Quality of felt is important as is manufacturing procedures because they dictate what is possible in the tension/density arena especially.
The short answer to your question is this, higher impedance systems need more energy, low impedance systems need less. How you achieve that by virtue of how you combine the various dimension listed above will have other consequences as I tried to describe in my first post on this subject. Putting the whole package together in a balanced way is something that can be done (I've done it, and continue to do it) by careful ordering and preparation along those lines. Fortunately, we don't have to worry about hitting every little minor variation because we can rely on judicious voicing or simple manipulation of strike weights to make *minor* changes to our hammer set for impedance matching (emphasis on minor).
The hammer, as delivered out of the box, if well made from quality materials has a lot of structural integrity--it has as much as it will ever have, in fact. There is nothing you can do to the hammer at that point to increase its structural integrity. Quality felt is meticulously prepared, graded, blended, interlocked and if the hammer maker doesn't make a mess of it, it gets to us just that way. Anything we do to it after that is a disruption to that structural integrity. That's a simple fact. You may argue that the manipulations you make are necessary for the tone to become what you want and that may be true. I would say it's a matter of degree. We will always have to do some fine tuning of the set for various reasons. But if you have to make major manipulations then the hammer was ill suited to the piano that you ordered it for. Still, any manipulations you make do attack the structural integrity of the hammer. Our goal should be to minimize the intrusions.
I firmly believe that a hammer can be delivered that has the inner structure necessary to produce something very close to the tone that we want and need for a given instrument if we understand the instrument and the hammer requirements and how they must work together. I believe that because it does happen. Not always, not always on the whole piano and not always in the same sections. But it does happen. When it doesn't we need to understand why and what accounts for that. There's more to it than just the vagaries of natural products and manufacturing processes.
Getting there is a challenge and requires a careful analysis of all the dimensions on which a hammer can be produced and understanding how those balance each other in terms of what we need the hammer to do along with the particular impedance characteristics of the piano (have I repeated that enough?). I have ordered them that way and received them that way. There is still some work to be done to cover what I think is our basic range of requirements but I think it's eminently doable and don't believe it requires that many iterations.
I guess that was more than a few things. That's it for me on this, for now anyway.
P.S. I'd like to have attached some images to illustrate some of the points I was making but having to go back into the website, download, attach, label, describe, wait, come back, reference...too much trouble, so little time. It would be nice if that could change but I'm not holding my breath.
David Love
www.davidlovepianos.com
Original Message-----
From: Fred Sturm [mailto:noreply@egroups.ptg.org]
Sent: Thursday, April 11, 2013 7:19 AM
To: David Love
Subject: Voicing: RE:hammer design
What I am gathering from your response is that it is less a matter of impedance and more a matter of mass. The first question to be asked is how much mass is "ideal" to drive a given system. Having established that, a certain small range of action ratios becomes necessary to match that mass to the pianist's fingers. A higher mass means a lower ratio, hence lower acceleration and end-velocity, and lesser range of possible velocities.
Lower end-velocity means (leaving out the precise details of why, but essentially more "dwell" on the string, slower reversal of direction) more lower partials and less higher. So if we want the characteristic range of partial mixes that is essential to the quality of piano tone, meaning more higher partials at louder volumes, we need a denser or stiffer hammer. I would tend to argue against the notion that that denser or stiffer hammer should be voiced in a "layered gradient" as the whole story of treatment.
That is certainly one approach and a philosophy that many have espoused, but I think it is a mistaken one, that deep shoulder treatment should be the basis, then a little surface gradient for attack sound at lower volumes.
Practically speaking, heavier hammers are our reality. Does anyone make a hammer that would match a Steinway M of the 1920s for mass and profile? If someone does, please let me know. While there seems to be at least some movement in the direction of somewhat lighter hammers, it is slow in happening, and doesn't approach that 1920s model (not to mention 19th century). And it is interesting that there seems to be more of a tendency on the part of rebuilders (and re-designers) to favor more mass in hammers rather than less, at the same time as the same people advocate for a less dense hammer.
Take, for example, David Stanwood's familiar demonstration of adding effective mass to hammers using binder clips, that seems to be pretty universally accepted (by those attending his classes) as producing a better tone quality. Or take Dale Erwin's notions of action geometry which seem to favor a relatively low action ratio, hence a higher mass hammer. The only voice I can think of on the other side of the question is Ed McMorrow's, and most people seem to regard him as pretty far out of the mainstream.
Much of this is historically driven: the hammers available to us have been those provided by hammer makers, whose main clients (until fairly recently) have been manufacturers, and they have wanted more mass and higher profile.
So we put those hammers on higher ratio actions and then try to deal with the results, with all sorts of ad lib methods: move the capstans, try to remove hammer mass (staples, bits of molding, thin sides), remove wood from wippens, add "turbo-springs", magnets, etc. A more rational approach would be to match the original hammer mass, but that isn't available, and seems not to be acceptable to the market, or not to have a large enough market to be economically viable. Maybe that can change.
-------------------------------------------
Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
"The true sign of intelligence is not knowledge, but imagination." - Einstein
-------------------------------------------