Got a question for you (or anyone else who can answer it): Do you know of a way to measure the individual (and the overall) string tension in my 56" 1913 Ricca (sn 37123) with the strings in the piano and pulled up to pitch? And, what tools do I need to do it with? I'm just curious as to what the scaling in my piano is like and if it would benefit from rescaling. It currently has a 56" A1 speaking length, not sure what the speaking length of the lowest tenor note and highest bass notes are, A1 - F#10 = double-wrapped monochord, G11 - B27 = single-wrapped bichord, bass/treble break at B27/C28, C28 - C88 = plain triple-string unisons. I personally don't want to put any wound strings at or above C28 (I like the sound of plain strings down there but my piano needs some voicing :)). Do you think if I knew the string tensions and some of the other speaking lengths it might help to determine if my piano would benefit from rescaling? Also, what do you guys do when you rescale a piano? --- Delwin D Fandrich <pianobuilders@olynet.com> wrote: > Gentle Readers, > > In an earlier post I found myself referring to the > overall scale tension as > a way of categorizing scales. An example I gave > referred to a scale having > 45,000 to 46,000 lb (20,400 to 20,900 kgf) scale > tensions as a > 'high-tension' scale. For this offence I should > receive at least a slap on > the wrist though, as I think of it, something even > more severe does seem in > order.... I can only plead for your > mercy--especially since not one of you > has yet discovered this offence and I have willing > come forward with my > confession! (And, I might add, some of you have no > excuse: I've gone into > this in several of my classes and you have been > there! You know who you are > but, not to fear, for your protection I'll not > identify the guilty.) > > The overall tension of a piano scale by itself does > little to define it's > tonal characteristics. This is the sum of individual > string tensions and > those can be wonderfully smooth and consistent or > they can be scattered all > over a rather large ballpark. The typical piano > scale--at least those based > on the scaling technology of the late 1800s and > early 1900s will typically > be scattered all over that ball park. They will be > up and down and back an > forth throughout the bass, often defying any kind of > logic; they will > usually be quite low through the low tenor climbing > up rapidly to become > high to obscenely high through the tenor; they will > drop down again to some > lower figure through the upper-tenor/low-treble; > finally, they will end up > quite low through the upper-treble. > > Just how do you categorize a scale like this? > > It is quite possible--though, perhaps, not desirable > for structural > reasons--to rescale a piano having, say, 36,000 lbs > (16,300 kgf) originally > and end up with a much higher overall tension, say, > 40,000 lbs (18,200 kgf) > and yet give the overall piano voice the tonal > characteristics of a properly > scaled piano having somewhat lower tensions. > > Consider a typical small piano scale (It doesn't > have to be a small piano > but these are my current interest, so pick anything > below 185 cm.) having > the very common hodgepodge of tensions described > above. By rescaling this > piano (and probably installing some new bridges) the > bass scale is evened > out (not changing the sum of tensions all that much > though usually they'll > want to go up some), the low tenor is brought up and > the high peaks through > the mid-tenor are brought down (leaving the sum of > tensions through the > tenor section pretty much unchanged), the low treble > section will probably > be brought up some (raising the sum of tensions > somewhat), and the > upper-treble will be brought up a lot (raising the > sum of tensions a lot). > Now, even though the overall sum of tensions will > have gone up by some 4,000 > lbs (1,800 kgf) the tensions through the critical > mid-tenor section have > actually dropped considerably. > > The result of all of this will be a smoother, > cleaner and more defined bass > section, a smoother, less noticeable bass/tenor > cross-over, a more dynamic > mid-tenor and a brighter, cleaner treble section. > The piano will be easier > to voice and will require less artificial hardening > of its hammers through > the treble. In other words, it will be a more > musical piano even though its > sum of tensions is some higher than I would like. (A > nice side effect for > the tuner will be better tunability.) > > I prefer to categorize stringing scales--assuming > they are of reasonably > uniform tension--by looking at their average > tensions through the > tenor/treble sections. By my personal definition a > low tension scale is one > having individual string tensions between > approximately 150 & 160 lbs (68 & > 73 kgf.). A high tension scale is one having > individual string tensions > above 180 to 190 lbs (82 & 86 kgf). String tensions > higher than these don't > belong on pianos of any type or size. (OK, > obviously, the individual string > tensions of the wrapped strings will be higher than > those of the individual > plain steel strings.) > > Now, just in case I don't quite have everyone > confused yet, please note that > this somewhat arbitrary differentiation does not > speak to scale length. When > scale length is factored in we can end up with: > -- Short low-tension scales, > -- Long low-tension scales, > -- Short high-tension scales, and > -- Long high-tension scales. > Each of these will have its own peculiar tonal > characteristics and will > require its own unique soundboard/rib > characteristics, soundboard loading > characteristics and hammer mass and resilience > characteristics. > > Regards, > > Del > Delwin D Fandrich > Piano Designer & Builder > Hoquiam, Washington USA > E.mail: pianobuilders@olynet.com > Web Site: www.pianobuilders.com > __________________________________________________ Terrorist Attacks on U.S. - How can you help? Donate cash, emergency relief information http://dailynews.yahoo.com/fc/US/Emergency_Information/
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