We need a dynarepinertiameter, don't have one. Fenton ----- Original Message ----- From: "Richard Brekne" <ricb at pianostemmer.no> To: <pianotech at ptg.org> Sent: Wednesday, October 08, 2008 12:52 PM Subject: What's all this I hear about Inertia ? > Hi Fenton. > > Grin... you make a great case for Bob Hohfs approach to the whole > issue. Still, both are simply tools these two different minds use to > help illustrate for us, and themselves a bit more of what actually is > going on... provide perhaps more justification for why the <<bubble>> > test works as well as it does. Heck even Stanwood has a tool for > arriving at this... he simply got his gang to average as many pianos as > he could possibly measure... taking the mean area as a kind of > expression of player preference. Given some 10000 instruments or > more... his averages fall into the field of statistical science and as > such he has pretty solid backing for his claim. > > In the end tho... as you say... it comes down to feel. Unless you are > out of the norm... say like a Horowitz or something... then your > educated feel should be a pretty good measure. > > Cheers > RicB > > > Agreed as far as it goes, tho you do change the key inertia > quite a bit... > > which several have offered opinion on. The only two formal > studies I know > > about the affect of key ratio are Dr. Stephen Birketts > treatise on the > > matter ( http://www.pianostemmer.no/files/key_balance.pdf ) > and Bob Hohfs > > empirical experiments that bark up the exact same tree about > half way up > > and echo Stephens results quite nearly exactly. The effect of > key inertia > > / key mass on dynamic touch is quite interesting. The math in > Birketts > > paper requires a bit of study unless you are adept... but > with a bit of > > work most who have dug through their high school pre calculus > and physics > > stuff should be able to make sense of it easy enough. > > > > Cheers > > RicB > > > I don't think formulas will give me much here. A while back Nick G. > talked about tire shops spinning a mounted tire to balance it, it > just works better than the old static bubble.The best test for > inertia in the key is to play the piano making note of what feels > right. If you play a lot of pianos and take a peek at the leading I > think you can gain an understanding of what that lead feels like. > Too little lead has a weird fell as well. Just my opinion at the > present time. > Fenton > > > >
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