Help regulating sostenuto

[Michael Spalding]

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Dale,
Perfectly clear.  I remember reading your post, too, although at the time the importance didn't sink in.  When I just look at a sketch of it, it seems like such a small movement.  Another reminder that little details really do matter.

Mike


----- Original Message ----- 
From: 
To: spalding48@earthlink.net
Sent: 12/18/2005 4:58:23 PM 
Subject: Re: Help regulating sostenuto


  Mike & All
    The real problem is in the design of the system itself. As in the case of the Steinway System which, has the same problem, the pivot pin point of the tray is not in line with the under lever pivot points, which creates  all kind of problems including problem of up,stop adjustment. 
   The difficulty lies in the design of this system which, many piano makers use. When the pedal is depressed the actual location of the under lever center pin is raised out of it's at rest position causing the under lever to hit the up stop earlier than it does with just ordinary key lift.  So you raise the up stop but then the free play with just key play & no pedal cause the damper to travel farther up then it needs to causing a  noticeable klunks back down on the end of the key which is felt with the finger. Pianist hate this by the way. 
   If the up stop is set too low the damper binds against the bottom of the up stop rail causing shorten key dip /after touch.  They hate that too. Gives a false dip reading as your trying to set it.  ............. DAMHIK
     The under lever center pins are actually rotating around the tray pivot. See the problem?  Therefore you can't have a very accurate setting of the up stop for both function of key lift & pedal lift. In the case of the Yamaha or redesigned Steinway system I posted about earlier this year both functions will work equally well when the tray pivot is in line with the under lever pin or at least a lot closer to it. Perhaps Kawais are like the Yamaha system? Dunno
  To mitigate this problem with your knabe system the pedal must be adjusted so that the free play in the pedal is minimal & the tray engages the bottom of the underlevers  almost immediately. Then fudge each adjustment so function overall is reduced as little as possible.
  If there is a large  amount of free play  before the tray engages the levers the under levers actually dip down towards the key end felt before they actually begin to rise up as the pedal is depressed ,causing more problems.
  Is any of this clear? A picture works better
   Dale Erwin
I'm aware of the problems which can occur if the pedal lifts the dampers
higher than the key.  Dean posted a nice description.   But what's wrong
with having the pedal lift just a little short of the key lift?  If the
pedal lifts to the same height as the whites, it's going to be lower than
that blacks, isn't it?

Mike,
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