Sarah Fox wrote: > Hi Ric, > > <<Of course the problem with this idea, is that springs do not in reality > determine touchweight, they only alter touchweight gradient. The assist > spring simply applies an upwards force which remains a constant.... say 20 > grams. Now if you are using 50 grams of force for a very quite touch then > this 20 grams counts for something... about 30 % of the total lifting force > of 70 grams... if however you are playing hard and apply a force of say 200 > grams... then suddenly this spring is only helping your finger our with 10 % > of the work. And as you get into really heavy play the spring has even less > effect. >> > > This is true, but only if one looks at the input side, without regard to > output. With greater spring assist and less leading, that same 200 g of > force will produce greater hammer velocity and therefore more sound. > > How? If a greater proportion of your counterbalancing is done by spring > force, rather than key leading, there is considerably less inertia to fight > in the key during hard playing. Remember, the kinetic energy of the hammer > is transferred to the strings (to a greater or lesser extent, depending on > the resiliency of the hammers), while the kinetic energy of the keystick is > transferred into the front rail, where it makes no sound but a "thud." The > higher the ratio of hammer inertia to keystick inertia, the lesser the input > energy that must be delivered into the key to transfer a given amount of > energy to the string. > > Peace, > Sarah > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html http://www.hf.uib.no/grieg/personer/cv_RB.html
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