Long term pitch drop, was: Type O

[Frank Emerson]

Tom Wrote:
I'd say yes to both questions, but I have seen hard evidence that strings do indeed continue to stretch as time goes by.   

One of the pianos I've tuned for years has had its plate sprayed with gold paint sometime ago.  Including the agraffes.  And of course, even the strings have gold paint on them, too.  Except where they were inside the agraffe, of course.

The part of the string that used to be inside the agraffe is now on the tuning pin side of the agraffe.  You can clearly see an agraffe sized space where there is no paint.  These strings have stretched a good half inch since the plate was painted, which was done long before I took over servicing the piano.

You assume that the piano was at pitch when the tuning pins, plate and strings were painted.  My guess is that anyone who would do this to a piano did not bother to bring it up to pitch before the paint job.  Furthermore, guessing at the condition of the piano before such a paint job, it was probably pretty flat.

Alan wrote:
It's like the other question I posed and have never felt I had a satisfactory answer: Since a piano cycles up and down, typically, with humidity swings, why doesn't it always stay centered around the last tuned pitch. <clip>

Strings that terminate on the bridge at a point near the center of the soundboard will be influenced to a greater extent by humidity changes than those nearer the perimeter of the board.  Other less obvious factor contribute to irregularities in pitch change from string to string.  In the long term, we cannot assume that the soundboard and ribs can return to providing exactly the same suppose to each and every string, just because the moisture content has returned to the conditions existing when the piano was last tuned.  

>Do the pins turn?

When I was on the Mississippi Gulf Coast, an old-timer told me about a rich customer who bought a new piano and had it delivered to his yacht.  He couldn't understand why it kept going out of tune so quickly.  He decided to fix it, once and for all.  Immediately after one last tuning, he welded the tuning pins to the plate.  As you would imagine, all he proved was that pins turning was not the source of the pitch change.

>Does the wire just keep stretching?

As others have stated, once the piano has stabilized, I doubt that this would be a major contributor to long term pitch drop.
 
>Why don't we know?

We will never know all the answers, especially if we ask the wrong questions.  What about the wood components of the sounding body?  Assuming, for the moment, there is no movement of the pins or stretching of the strings, do you suppose that every string would return to exactly the same pitch once the moisture content of the board is exactly as it was when it was tuned?  I can't say that I "know," but I think not.  There are a lot of folks who know a lot about how pianos behave, but very little of this "body of knowledge" is universally agreed upon.  Does this mean that much of it is not fact, but opinion?  (Whoops!  That's another thread, and another can of worms!)

Implicit in your questioning is another question: Can't we build a piano that is more stable?  The answer to that is: Yes, but it wouldn't sound much like a piano.

Frank Emerson
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