Why a string goes out of tune.

[David Ilvedson]

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Wim,

It's possible your problem is in the tuning pin.  IMHO...You have=
 to have an understanding of what is going on with the=
 string/tuning pin.  (And you may already do all of the following=
 things)  Making pitch changes with your tuning hammer and then=
 pounding 12 times to see if it stays in tune is going to result=
 in unsatisfactory results.  When you pound (I prefer key/hammer=
 action mf) you should be using your tuning hammer at the same=
 time.  In other words, slight impact pressure on the tuning=
 hammer with some key/hammer action can move the string and the=
 pin the little amount you want.  Tiny changes in pin/string=
 movement is what your after.  Remember any kind of change in=
 pitch needs going over again.  When I'm fine tuning, I'm making=
 1 cent or less changes usually with just some impact pressure=
 increasing slightly in force with key/hammer action.  If the=
 slight impact pressure doesn't put it where I want I will have=
 to make a tiny change in the tuning pin which will happen with a=
 little more impact pressure.  The idea that you must come above=
 the pitch and pound it down into tune aint going to make it in=
 fine tuning.  If that string is more than 1 cent, I will tune it=
 several times, tuning all strings in the unison as many times as=
 it takes.  I'm tuning unisons as I go and I use a SAT III with=
 minimal checks.  

David Ilvedson


----- Original message ---------------------------------------->
From: <Wimblees@aol.com>
To: <caut@ptg.org>
Received: Tue, 13 Apr 2004 10:23:58 EDT
Subject: Re: Why a string goes out of tune.

In a message dated 4/12/04 9:21:15 PM Central Daylight Time,=
 claviers@nxs.net writes:
 
Jim: First you say:
 
"This means that no matter how hard you pound, you will NOT=
 equalize the tension between speaking lengths and string tails. =
 You will break something before you can pound hard enough to do=
 that.  What you WILL do is cause it to move if it is about ready=
 to move
anyway."
 
So I asked, if you don't pound, (or play softly), will the string=
 move any way. So you answered:
No, Wim, I am NOT saying playing the note softly will equalize=
 the tension
across the bridge.  You know that.  I said pounding will cause it=
 to move
if it is about ready to move anyway.  If the tension is not=
 equalized
across the bridge, but the string is about ready to move, but you=
 play
softly, nothing will happen.  But if you do pound, or if the=
 pianist
pounds, then it will move, and the pitch of the speaking length=
 will change.
So does this mean I should pound to equalize the string? If I=
 don't pound, and the string doesn't equalize across the bridge,=
 then when the pianist plays hard and does move the string, then=
 the piano will be out of tune. 
 

"Now consider the fact that you have a whole bunch of strings=
 whose tensions
are only partially equalized across the bridge, because there is=
 no way you
can completely equalize it.  All it takes is for the relative=
 humidity to
change, the bridge to swell or shrink, or the temperature to=
 change so that
the difference in expansion coefficient between wood and steel=
 will cause
the string to slip a microscopic amount at the bridge, or someone=
 to pound
the key; the string will move at the bridge, and your perfect=
 unison tuning
will be spoiled.  I think this makes lots of sense."
 
To me you're saying two different things. On the one hand you're=
 saying not to pound, because the string will move across the=
 bridge anyway. But you're also saying the string won't move=
 across the bridge until you (or the pianist) plays loud. So what=
 is a piano tuner to do? Tune softly, and let the strings not=
 move across the bridge, or play loud, and move those strings. 
 
The other thing you're saying is that a little change in=
 temperature or humidity will cause a string to go out of tune. I=
 can accept that to some degree. I saw your demonstration of that=
 at one of the conventions. But you were taking a hair drier to a=
 string on a mini back. On the concert stage, most of the time a=
 piano is not going to be subjected to that kind of extreme=
 changes. I would think that having the string equalized would=
 prevent most microscopic differences. 
 
Now granted, pounding to equalize tension, and playing so you can=
 hear the note, are two different things. I never said I listened=
 to a pounding note as the final answer. All I said is that I=
 pound to set the string and the pin. 
 
What makes sense to me is that if I don't pound every note, to=
 get every string to equalize across the bridge, I'm asking for=
 trouble. 
 
Wim 
 
 


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