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
This PTG archive page provided courtesy of Moy Piano Service, LLC