Hello ,hello, me again, Evaluate the hammer weight/strike weight : OK Even the SW or hammer weight : very advisable certainly. Force to a certain curve does not mean much out of providing a supplementary tactile sensation within the action. Even the jag at the break : No definitive answer. On may keep in mind that the hammer weight and shape retained is supposedly there for tonal reasons first (even if this was not computed really, obviously). Then if a particular instrument hammers have been retained because the output power they provide seem good for the balance of tone of the instrument OK to keep something near of that. Then, one may feel the compelling tendency to "make something" to help the evenness of the instrument, or to correct a supposed or real missing part in the scale. There decisions can be made to use heavier hammers, or thinner, or with a more pear shaped top, a better felt, etc. One may understand that the balance of the action will be changed and in need to be corrected a lot with more lead or less lead in the keys, if he change the SW more than a few 1/10 g. Even retaining the original hammer weight but gluing the heads with a different rake or at a different place on the shank (129.5 for 130 mm for instance) will change the balance of the keys (and one have to verify the DW/UW). I believe that we may have an idea of the tone we can expect and we want first. Aint an easy task of course as it is a matter of experience. Analyzing the tone, and the sensation of weight vs. power of the notes at the break may more easily show us if adding mass on the treble side, or taking (a lot) off at the end of the bass will be good or not. Providing an extraordinary sensation of evenness of balance note to note (that is felt mostly in lighter modes of play anyway) is certainly an element of comfort to the fingers of the pianist, but I say it can give something unnatural if it is not in harmony with the other parameters of the instrument. There certainly the good choices are something not everyone can make. More then that, if the action geometry (that play a role in dynamic mode) stay less than ideal, unevenness will appear abruptly in accelerations , giving the impression that the instrument is somewhat ambivalent. It can be very surprising I say. Amelioration for a basically well build action and instrument is very certainly a good thing. Correction of the action and keys problems is way more difficult to envisage while retaining the keyboard. Weights and a semi static method of evaluation (or levers for that matter) can help the analysis, but they can't show it all so it works only partly the other way. Al bla blah Isaac -----Message d'origine----- De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la part de Richard Brekne Envoyé : dimanche 22 août 2004 14:20 À : Pianotech Objet : Re: SW heresy? Sarah Fox wrote: > Hi all, > > ... > I was advised off list that I shouldn't force the hammers to > artificially conform to a standardized Stanwood curve but to simply > even out the jags to make the action smooth from bottom to top. > There's something to be said for this idea. Sure there is... its easier, and it provides the most important aspect of Stanwoods whole philosophy IMHO... even strike weights. No hops or jumps. The entire remaining bulk of why to choose any particular Strike Weight curve remains largely a subjective matter still up for discussion in most regards. But I dont personally see any real room for argument as to whether or not evening out Strike Weights has a very benificial effect on the touch of the action. > > But as I got to thinking about the SW curves, I was wondering, where > do they REALLY come from? As far as I know these are the result of two things basically. First... Stannwood simply took measurements from a few thousand pianos in order to gather enough data by which to arrive at some basic statisical quantities like <<average>> <<mean>> and the like for use in establishing tendancies. Then two... they are the natural result of how he implements his SW or balance weight formula. Remember there are a few givens in that formula when solving for SWs. You have to settle on a BW, WW, KR, and SWR. The only things left are FW and SW. The curve you select for one of these affects the shape of the curve for the other of course... and if you dink around with a spread sheet I have that Mark and I (mostly Mark) worked on a while back, you can see this in action. In the end tho... Stanwoods particular curve shape is somewhat a subjective choice me thinks... tho he may say different. He can and from time to time does provide custom curves for given situations that are not quite this same shape. Steinways own default curve is somewhat flatter btw. > Contrast this function with other functions that might actually relate > to optimal hammer mass: String length and mass both decrease with the > note number, with a function that is concave upwards. Note frequency > increases with a function that is concave upwards. Note period > (inverse of frequency) increases with a function that is concave > upwards. The Stanwood curve seems rather meaningless with regard to > any of these functions. For instance, it might be good to match > hammer mass to string mass by some proportion. Right? As the scale > goes up, string length and mass approach an asymptote of zero. > Therefore, shouldn't hammer mass approach an asymptote of zero? > Instead, the curve starts taking a dive in the treble. If the scale > went up well past 88, hammer mass would eventually crash to zero. > Because these curves do not have the same form, the relationship > between hammer and string mass is anything but constant. That doesn't > make sense. To my knowledge no one has actually approached hammer weighting this way, at least not from a mathmatical models point of veiw. I wouldnt be suprised tho that Steinway has rather fallen into their selected curve shape from a trial and error perspective.... listening to different configurations over time. The issue of hammer weight has been discussed and debated for a very long time. Tho many insist that it is the actual weight/mass of the hammer head itself that is important, and that the SW is a meaningless quantity with regards to piano sound. Some also claim that the addition of lead is a big no no exactly because of the effect lead mass has on the sound and because of how it displaces the center of gravity for the leaded hammer. The effect of lead in a hammer on sound is a claim I personally find difficult to swallow... but who knows ? > > So is this something that is the way it is just because of tradition > -- because the cauls are built that way, and that's what ya' get? It seems reasonable to assume that the chosen manufactured shape of a set of hammers would directly affect the basic shape of the curve. Cutting of hammer sets into individual hammers no doubt accounts for some of the spikes... as does variations in wood density... and probably a lot of other things I havent really thought about. > > Now that I look at my linear SW curve (with jags), I'm wondering if > this isn't REALLY a closer match to something meaningful (like string > mass) than the idealized Stanwood curves. Any thoughts, y'all? I think Sarah, that the most important thing here is that the SW curve you select remains very evenly graduated, is within reason with respect to what kind of mass levels you need in the keys to counter balance for your desired BW and given SWR (Balance Weight Ratio). > > Peace, > Sarah > Cheers RicB _______________________________________________ pianotech list info: https://www.moypiano.com/resources/#archives
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