[CAUT] Re: Temperature and pitch

[Ed Sutton]

Jim,

Yes, I do mean the hair drier just as an experiment.

I'm now thinking a better experiment would be to close the lid flap (front
lid or fly leaf)at night, come back and play when the room is cold; then if
it sounds o.k., open the flap and see if the high treble goes sharp. 
(Remember the DC system is keeping the belly warm, and she never opens the
full lid, only the front flap/lid/leaf).

This teacher has had bad technician relations because of her many demands.
At first I wondered if she was hallucinating, but I've listened very
carefully, and am finding technical causes and fixes for the various sounds
she complains about.  She has a 1970's Mason & Hamlin BB. It is a glorious
sounding instrument with a thousand flaws of sloppy manufacture.  Between
the two of them, it is quite a challenge and an advanced education.  At
least she gives me good referrals.

Thanks for your comments.  I find your explanations of
plate/string/temperature interrelationships very clear.

Ed Sutton


> [Original Message]
> From: James Ellis <claviers@nxs.net>
> To: <caut@ptg.org>
> Date: 3/2/2005 5:33:53 PM
> Subject: [CAUT] Re:  Temperature and pitch
>
> Ed,  
>
> The strings go sharp when they are cooler than the plate, and flat when
> they are warmer than the plate.  I happens fast - a matter of a very few
> minutes - even seconds if there is a draft.  If the piano has been
> subjected to a major temperature change, wait a few hours until everything
> in the piano has come to the same tempterture, and it should be back on
> pitch.  The cast iron plate and the steel strings have similar temperature
> coefficients.
>
> If this is what the instructor's problem is, it should not happen if she
> leaves the piano closed.  I wouldn't recommend blowing a hair drier on the
> treble strings unless you are just doing it as an experiment.  But if you
> do, you should hear immediate results as the strings go flat.  Take the
hot
> air away, and they will slowly return to pitch.
>
> You probably read my account about that problem I had 50 years ago when
the
> instructor would come into a sweltering hot steamy room early in the
> morning, and open all the windows when it was cold outside.  That will do
> it every time.
>
> But in your case, to make the treble strings go objectionably sharp
> relative to the remainder of the piano, it would take a cool draft just on
> the treble strings only.  Good luck finding out what's doing it, or else
> what makes her think it's happening.  Some people's ears change with the
> time of day.  I know.  Mine do, and I make allowances for it.
>
> Jim Ellis
>
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