Yamaha Jumping Jacks

[David Ilvedson]

I was going to mention the same thing...I don't hear many institutions actually doing this...?

David Ilvedson, RPT
Pacifica, California


----- Original message ----------------------------------------
From: "Geoff Sykes" <thetuner@ivories52.com>
To: Pianotech <pianotech@ptg.org>
Received: 11/3/2005 9:19:13 PM
Subject: RE: Yamaha Jumping Jacks


>Follow-up to my previous post, (below). Please bear with me.

>I had the opportunity to do preps on two new out-of-the-box Yamaha uprights
>today, so I did a little experimenting with this double-strike phenomena.
>What I think I may have discovered is that it just may be operator error on
>us, (or is that we), techs that is causing this. 

>What I found was that when pressing the key down slowly I was sort of
>unconsciously pausing, just for an extremely minor moment, at the exact
>instance that the jack just starts to move out from under the butt. At that
>exact moment, when you are moving slowly, there is a very slight, but
>noticeable, increase in resistance as the jack starts to rub against the
>butt in it's move to escape. What I found myself doing was reacting to that
>subtle increase in resistance and almost unconsciously changing the motion
>of my finger pushing down on the key. In other words, I believe I was
>perhaps actually introducing the phenomena into the system myself. 

>What I observed happening was that since the hammer was already in motion,
>the slight pause that I was introducing allowed the hammer to continue to
>move, leaving the jack and subsequently striking the string and then
>bouncing back, at which point I would continue pressing the key allowing the
>action to complete it cycle and giving me that second strike.

>When I carefully monitored my finger movement, forcing myself to move
>smoothly through that subtle point of increased resistance, I could not
>reproduce the effect. It only happened again when I stopped thinking about
>it. And even though the speed of the key press is within a very narrow
>window, it was definitely and easily reproducible, on any key on both
>pianos.

>My guess is that this may turn out to be a new piano only effect. Once the
>piano has been played for a while and "broken in", and the butt leather
>smoothes out a little this may be impossible to reproduce at all. And as
>long as I'm guessing here, I don't think anyone but a tech could even MAKE
>it happen. Certainly not the person at home just playing the piano under
>"normal" circumstances. 

>I find the combination of piano action physics and our human reactions to
>what we see and feel as a result of those physics all very interesting. I'll
>shut up now.

>-- Geoff Sykes
>-- Assoc. Los Angeles




>-----Original Message-----
>From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On Behalf
>Of Ric Brekne
>Sent: Thursday, November 03, 2005 11:19 AM
>To: pianotech
>Subject: Yamaha Jumping Jacks


>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

>-------------
>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 _______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives

>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives