twangy ... again!

[Edward Carwithen]

  I had this problem with another piano, and all of you were so kind to
offer suggestions about how to deal with a twangy sound.  No I have it
again, on another piano, but this piano has been a problem in one way or
another for quite a while.
   Yamaha grand, owned by church.  The player really hits it!  It needs
tuning often, but the worst part is that she complains about the sound of
certain notes... not always the same notes.  Today it was G5.  Sure enough
there is a twang as the string is struck.  F#5 also to a lesser degree.
Rest of the piano no problem.  Well, yes there is a problem with D# 5,
where the upper treble begins.  It has no resonance at all.  Note just
dies.  I couldn't figure out what to do with that either.
  Back to G5.  There is a bit of false beat on two of the strings, but that
isn't the cause of the twang.  I have voiced, checked for loose bolts and
screws, etc.  I would like to think that the sound is coming from the drums
behind the piano (they do a lot of gospel type stuff), or the guitar
strings.  Just can't find anything.  She (the player) is very sensitive to
the sound and it is major bothered.
  I am losing my confidence over this animal.  I can't seem to fix it, and
I don't know what to tell her.
  
  
Ed Carwithen
Oregon