voicing

[Richard Brekne]

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Ron Nossaman wrote:

> >A couple questions here... I know several guys who routinely use a scaleing
> program
> >to redesign the scale when restringing / rebuilding. These fellows
> typically are
> >repairing cracks in the soundboard (shimming). They take care to check
> "downbearing"
> >before and after lessening tension on the strings. Often they lower the
> plate a bit
> >(something I question the reasoning for ... read Ed McMorrows book).
>
> * Doesn't anyone ever check the crown under load? That is, before lowering
> string tension? By my way of thinking, if there is little enough downbearing
> to necessitate lowering the plate, there had better be adequate crown in the
> board to take the load or the board will be driven flatter, or farther past
> flat, than it already is. Increased bearing angles = increased soundboard
> load, and if the board is already flat... where's the fix?

Exactly my point. Personally, tho not an accomplished rebuilder myself, I have not
seen a soundboard that has both too little downbearing and at the same time plenty
of crown.

>
>
> * You didn't mention checking crown either. Do you? Also, I wouldn't worry
> too much about sneaking up on the tension. Just chip and rough tune to pitch
> immediately after stringing and keep it there while it settles in.
>
>  Ron N

Hmm.. I guess I need to be more precise. String deflection at the bridge is measured
before easing off string tension, and then again afterwards. The difference gives a
reading of how much the board rises with tension off. ie. crown. Does this jive with
your meaning of crown ? If not I would like to hear how you check crown.

This is in any case what is done here in Norway by most of the fellows doing rebuild
work. And as I said in my last, they use this info most often to decide how much
they are going to lower the plate by. I have never heard of anyone over here even
think about raising the plate. (grin.. except me)

What makes me scratch my head about this is that these two measurments only give a
picture of the present condition of crown. If a rebuilder increases the press
downwards by lowering the plate, with only this bit of info at hand, then this seems
to me to be an uninformed "choice" unless he / she knows how much crown there was
when the piano was new. Does this make sense ?

Richard Brekne

I.C.P.T.G.  N.P.T.F.

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