The issue has to do with what's been termed "action saturation". As one plays up the dynamic ladder with ever increasing force the key flexes more and more. At a certain point, before the pianist has reached the top of the dynamic range, the excessive flexing in the keys prevents a harder blow from accelerating the hammer any faster. The upper level of fortissimo is therefore limited by the flexibility of the key. You can imagine if the key were made of a very flexible material that on a blow of any force you would just push the key though its dip range before the back end of the key even started moving. That's the basic idea, though I'm sure others can explain it better. The reason it happens on D's is because of the long key length and on Steinways in particular because the height of the key has been reduced somewhat to accommodate the accelerated action bearing which is considerably thicker than the thin felt punchings previously used. The reduction in height makes the key that much more flexible. The amount of flex is deemed too much when the point of action saturation is reached at too low a level in the upper end of the dynamic range. David Love davidlovepianos at comcast.net www.davidlovepianos.com -----Original Message----- From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of Richard Brekne Sent: Saturday, May 03, 2008 7:03 AM To: pianotech at ptg.org Subject: Flexy S&S D Keys Hey: I'd like to know how much flex is too much and why just S&S D's? Gerald McCleskey RPT
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