Depowering a Piano

[Isaac sur Noos]

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Hello, Malinda,

I'll mostly just answer on the breaking point. For all practical
computations on piano scales, the breaking point of the wire (that is given
to us by the wire maker) is lessened 25 % - the new value is then considered
breaking point and we try to get the strings in a zone where they are know
to tone well, admittedly it is around 50 to 70% of this lessened breaking
point (hence your comment). This is called solicitation of the string ,
don't know if the term is correct in English.

The problem we meet when repairing older instruments (before 1930) , that
where build when the wire makers produce strings that where less resistive
to tension (less stiff also) and when we use modern wire on them, is that
the solicitation gets very poor, and the tone suffer - often it gets harsh,
a little like with pianos that lack down bearing, too explosive and not
singing enough. We have the same on modern instruments, for instance
STEINWAY O, first plain wire B2 length 1110 mm , wire1025 mm the
solicitation is 35% of the (lessened breaking point) - while the tension is
491 Newton, not high but acceptable.

If on that piano you tune 1 whole step lower the tension will be 383 N the
iH goes up and the solicitation get even poorer at 26 % - I doubt any
pianist agree with the tone then
If you tune any piano 1/2 step lower the tone get horrible because of this .

 Stephen Paulello push us to mix wire of different stiffness in order to
keep the solicitation consistent toward the break he computed that the iH
stay the same as well as the tension so it may be worth a try . As the wire
he produce is covering a wide range it is possible (BTW I've seen the wire
delivered and it is better looking than Roslau actually, cleaner, more
shiny).

Back to the dinner table now.

Happy New year everyone.

Isaac

                       Pianotech

                        Isaac OLEG
                        accordeur - reparateur - concert  19 rue Jules Ferry
                        94400 VITRY sur SEINE
                        oleg-i@noos.fr  tel:
                              fax:
                              mobile:  033 01 47 18 06 98
                              33 01 47 18 06 90
                              033 06 60 42 58 77




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  -----Message d'origine-----
  De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la
part de Malinda Dobrins
  Envoyé : mercredi 31 décembre 2003 18:01
  À : Pianotech
  Objet : Re: Depowering a Piano


  I think I have an answer to your string breaking problem.  All strings
have a point at which they will break. The engineers have designed strings
to be below the breaking point by 30% or more. Once the energy imparted into
the string exceeds this percentage the string usually breaks.  Since we
can't control the increased energy put in by the pianist, we can control the
breaking point percentage.  The easiest way to do this is to lower the whole
piano 100 cents (a half step). The lower tension thus created willl increase
the breaking pooint percentage and thus absorb the increased energy before
the string breakage occurs. Of course, this can't be done when playing with
other instruments unless the players of the other instruments are willing to
transpose to the piano and vice versa.

  Recently I was in Atlantic City at a cascino where a piano player was
playing a Yamaha grand piano.  Playing along with him was a bass fiddler.
The piano player was also a pounder.  During a break I asked him if he had
string breakage problems. He said no because his tuner was tuning the piano
a half step lower and thus solved the problem of string breakage for him.  I
assume that the bass fiddler transposed his playing to fit the piano.

  Hope this is helpful.  Lee Dobrins
    ----- Original Message -----
    From: Farrell
    To: pianotech@ptg.org
    Sent: Tuesday, December 30, 2003 4:39 PM
    Subject: Depowering a Piano


    Yamaha C3, piano bar in nightclub. Serviced every two weeks. Always been
a good piano in very good condition. New piano player for last two or three
months. The guy is a major pounder. Lots of broken bass strings (maybe 10 in
the last two months - never before). The key bushings have also gone from
excellent condition to slapping neighboring keys.

    The guy I work for requested that I depower the piano by decreasing blow
distance and, correspondingly, key dip. Seems like a good idea. I had not
heard of that approach before. Seems to me the piano player will notice it
and not like it. But that is just my guess. I reduced dip in the bass by
0.075" - and then blow by about five times that - to about 1.5 inches. (From
middle "C" on down, I added 0.025" punchings on the front rail every
half-octave until I got to the bass where I added the three punchings to
each front key pin - so that there was a transition to the shorter dip.)

    I have seen recommendations for increasing let-off to depower a pounder.
I have never tried that though. Just curious whether anyone has any
experience with the technique I outlined above, and how much dip/blow
reduction is best to adequately depower the piano, but not aggravate the
player too much. The amount I used what just a wild guess on my part.

    Terry Farrell

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