instability

[Ron Nossaman]

At 02:41 PM 2/20/99 -0800, you wrote:
>Weird piano today.  It is a Baldwin Spinet, not too old, maybe 7-10 years.
>I tuned it in August, owner wants it done every six months.  
>  It was sitting against the wall, and there was a heater duct behind the
>piano, blowing hot air against the bottom of the piano.  Maybe that is the
>source of the problem.  Maybe not.
>  We moved the piano (on my advice), and I proceeded to check it.  A4 was
>37 cents flat on my SAT!  I did a pitch raise, and then did it a second
>time.  Then did some regulation things.  Then proceded to try to tune.
>lower section was flat again, OK, bring it up.  center section (C#3 to F#5)
>mostly flat in lower half of section, not too bad upper part.  Treble
>section flat.  OK, tune it up.  Go back and check.  C#3 about 8 cent sharp,
>next several notes equally sharp.  OK, bring back down. Get up to 4th
>octave, check octaves, C#3 (D, D# etc, up for half the octave is now 8cents
>flat.  OK, bring up, get to 4th octave, it is now 8 cents sharp.  The thing
>see sawed back and forth several more times.  I finally got it so the
>octaves didn't actually scream, and quit.  I will go back next week and try
>again.  Maybe it will have settled down by then.
>  I thought that maybe I had a broken frame.  I've never had a piano go up
>and down like that while I was tuning.  This was more than a little drift
>as you work on adjacent notes.  This was entire groups of notes going berzerk.
>  What say you, oh might gurus.  Any thoughts one what ails this thing or
>is it just haunted?
>
>
>Ed Carwithen
>John Day, Oregon
>


I'd say that when you go back later, the creature will probably have settled
down from the trauma of having been parked over a heating vent, and will be
much more docile and accommodating... within realistic limits. Alternative
two is a severely "S" curved crown in the soundboard. You get the weird
pitch seesaw from that too, and it's not that unlikely, especially
considering the thermal and humidity trauma it's gone through. 

 Ron