No Power Yamaha revisited

[Isaac OLEG]

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With a light bedding, I guess that under forte blow there is a distortion
that travel from the front of the keyframe towards the back, as the back
want to raise because the frame is not stiff enough.

Seem also that the hammer have less benefit of the mass of the whippen,
while if saturating we feel the action as being more driven towards the
hammer (if you see what I mean !)


On hardwood keyframe this is not a problem, and heavy bedding is not
feasible, the action would give a very knoky tone then.

But still there is a small zone where the change in bedding is changing the
tone from mellow to more straight.


Till next time !

Isaac

Isaac OLEG

Entretien et reparation de pianos.

PianoTech
17 rue de Choisy
94400 VITRY sur SEINE
FRANCE
tel : 033 01 47 18 06 98
fax : 033 01 47 18 06 90
cell: 06 60 42 58 77

  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Richard Brekne
  Envoye : lundi 26 mai 2003 21:36
  A : Pianotech
  Objet : Re: No Power Yamaha revisited



  A440A@aol.com wrote:

    Bill writes:
    >I agree that a good healthy blow will put the frame under pressure,
    >but if the BR doesn't have anywhere to go (because the glides are
    >contacting the bed),
      I have been wondering when somebody is going to mention the
entrainment of
    the keybed?  Once the glides are in contact, the action cannot move,
UNLESS
    the keybed is not absolutely rigid.

  Hmmm... I wonder about this. I know it makes sense.... and indeed that
very assumption has been the basis of how I've approached bedding the
keyframe for years. Yet the last few days has demonstrated that putting the
key frame under stress by turning the bolts down a bit more, significantly
afftect the power of the action and quite clearly decreases the amount of
movement in neighboring hammers and shanks at fff levels of play.  If it was
the keybed I suppose I would expect any instability to be most apparent in
the center of the keyboard, but I dont. Its always the bass and tenor
regions that have given me most trouble... especially the bass.

  I guess that the added stress of the bolts being turned down a bit just
makes the whole frame a bit stiffer, perhaps causeing the back rail to
strain up against the dags contributes to this ??. But I dont really see how
the increased stress beyond solid contact by the glide bolts is doing what
it seems to be doing.

     But we know the keybed isn't.  This is
    easily seen by depressing the pedals under a very lightly bedded set of
glides and
    observing them to lose contact with the keybed.
       So,  the extra power and tone being ascribed to heavier loading on
the
    glide buttons may possibly be a function of preload on the keybed?

  Hmmm... maybe...at least in part.

    And the
    observed differences between makes of pianos may be more due to the
differences
    between keybed strength than the flexibility of the balance rails??
    Wondering,
    Ed Foote RPT

  FWIW, I did the other Yamaha today... a C7, and one of our students came
into get ready for a performance and sat down to play whereby she immediatly
smiled up to me and said "AH.... there's some springyness to the piano
now... what did you do ?"... I asked her if she was certain it wasnt too
much and she played a bit and said it was just perfect.
  Rougly, they were a 3rd of a turn backed off from loosening the front
rails grip on a thin strip of paper and evened.

  All this is a bit new to me, so I'm having great fun reading Bills,
Rogers, and others thoughts on the matter.

  Clearly theres more to it then just gettting the glidebolts to all contact
the keybed.

  Cheers
  RicB

  --
  Richard Brekne
  RPT, N.P.T.F.
  UiB, Bergen, Norway
  mailto:rbrekne@broadpark.no
  http://home.broadpark.no/~rbrekne/ricmain.html
  http://www.hf.uib.no/grieg/personer/cv_RB.html


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