CAUT

Hello All.

We have a Steinway D where one note, C5 goes out of tune much faster than the rest of the piano.  I can tune the piano and come back in a week and that note is noticeably flat.  It has also developed somewhat of a false beat.  I've done everything I can see, tuning pin is fine, I tapped down the bridge pins, seated the string on the bridge.  I beginning to think that it is something I can't see, such as the string is weakening and is about to break.  The piano gets a lot of use so over the Spring break is my only window of time, so I would need to do is immediately since there is a big out-of-town group coming in a couple of weeks.  Unless someone can think of another reason for it.

Thanks for your thoughts.

Robert

It may be "just" weakness in the string, but it's also possible the becket is slowly slipping out. If you replace the string, check that the hitch pin is totally solid. If not, replace that too. Good luck!

There may be a problem with a slipping coil and the becket not seated too well or only part way through the tp hole. Check the tightness and seating of the coils and number of wraps on all 3 of the tuning pins for that note .check the tuning pin torque with an inch lb torque wrench the pins may FEEL tight but there could be slippage. I am dealing with the same issue on a Young Chang where the pins felt okay but octaves where out. The pins where easy to tune and seemed to be holding but the torque wrench read in the 20-40 range. You could also tune the note to pitch and treat each pin with very thin CA. Check the strike point of the hammer since if it is flat too much contact with the string may be knocking it out.....

The whole note, or just one string/tuning pin? I have had such an experience with one string where I finally determined that the tuning pin wanted to jump past the target pitch when being raised, but could be 'eased down' from above pitch - which is what I would do. Problem was that there was friction in the system that was touchy: I could pound the note and it wouldn't budge, but next day (or during a concert) it would drop 10 cents or so.

Solution? Always tune it up to pitch, not up from below. It was hard to learn to move the pin that minute amount when it wanted to jump, but I finally learned to do it, and the process became the basis of a transformative and much more secure stability technique: tune by manipulating the pin, using flex and twist and lots of persistence and patience (though tuning actually goes faster).

IOW, it is possible there isn't some gremlin at work. It could just be an ornery pin/pinblock interaction, together with an ornery frictional problem.

I'm a little late to the party here, but is it the entire unison, or just one pin/string? If it's just one, in a pinch, I think it would be a good idea to mute it. If it's the middle string, mute the outside strings with foam ear plugs (or something sufficient) against the neighboring notes and see if the dynamic level is acceptable for the performance. At C5, you're probably fine, but used your discretion. Most players are not going to notice this, and the audience certainly won't either. This is a much better compromise than to risk having that sour, nasty note being heard by everyone listening. 

This is obviously a simple bandaid until you replace the string with a proper coil and seat it properly at all termination points. Even if you replace this string before the performance, you're better off muting it anyway, as it may go south. 

Hope it all works out! 

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Lucas Kirby
Kirby Piano Service 

Piano Technician : EWU
Spokane, Washington
509-294-8717
lucaskirbymusic@gmail.com
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Thank you all for the suggestions.  I went through the piano and leveled the strings and mated the hammers.  I had been a long time.  It sounded much better.  Hard to say exactly how, but just fuller and "rounder".