Yamaha Jumping Jacks

[Ric Brekne]

Hi

At just past half blow on the upright piano the jack should already 
sufficiently in motion that by the time the hammer evntually would 
bounce back on a slow (but realistic) keystroke the butt should be able 
to push it out of the way.  If it cant, then there isnt really all that 
much that can be wrong. Either its not out far enough for this to 
happen, ie. a regulation issue, or something is preventing it from 
moving out easily enough... ie. some resistance in the action.

I've run into a few Steinway K's and Z's with this problem and I've 
solved it every time by a good regulation and appropriate spring 
strenghts. 

That said... Crescendo punchings wont really help me thinks in as much 
as one of my earlier attempts was to simply increase key dip 1 mm with 
no real change in the double strike at soft play. I think (not know) 
this is because one really isnt playing with all that great a technique 
in the first place and that the situation is bordeline relative to the 
technique of the pianist.

That said again... there are all kinds of good reasons otherwise for 
useing Crescendos... so buy em :)

Cheers
RicB

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Not to dis the Crescendo punching's, which I hear nothing but good reports
about, but this is not a soft blow problem, it's a slow key movement
problem. My experience with this double-strike phenomena is that the hammer
jumps off the jack about halfway through the keystroke, (in other words long
before the jack actually releases from under the butt), hits the string and
bounces back onto the jack, the keystroke continues through the point of
actual let-off where the jack actually does it's work of throwing the hammer
into the strings, and then the hammer bounces back correctly into the
backcheck. The key then completes it's stroke eventually landing onto the
front rail punching. My point of all this is that the double-strike is not
the result of a soft blow so much as it is the result of an improperly
functioning action during a slow key movement. It happens long before the
front rail punching's are even part of the picture.

-- Geoff Sykes
-- Assoc. Los Angeles