Knabe Tuning Mystery

[Thomas Cole]

The piano is an 1895 Knabe, art case upright in exceptional but original 
condition. The problem is tuning instability. I tuned it one year ago 
along with a Schimmel grand in the same room. The Schimmel sounded 
beautiful today, so much so that I declined to tune it. But the Knabe 
has become unplayable and out of tune in way I've never seen before.

Because of heavy rains, the humidity is higher than when I last tuned 
the Knabe (72%). I noticed the tenor strings were a little sharp, 
getting sharper at the tenor/treble break. Then the treble started out 
+25 cents and the top few notes were at or near +50 cents. Bass was 
slightly sharp.

The owner says that the Knabe tuning never lasts more than two or three 
weeks. He plays it much more than the grand, so this is a factor, but he 
is not a heavy player. The owner wants to restring, because strings are 
starting to break, but not change the soundboard. The board, bridges and 
pins look like new, but I was not able to check crown (owner afraid of 
hardwood floor damage if I move it).

How can I find out what is causing this tuning instability? Why would 
the tuning go so sharp in the treble, as opposed to the tenor where you 
would expect? Can anything be done in the course of a restringing to 
improve stability?

Tom Cole
on the Left Coast