Hi all,
My upright is tuned by a piano tech 2 months ago, recently I while practicing with silence pedal on, I discovered a unpleaseant sound "twang" so called at F5#. I plucked each of the three strings and using a tuning sofware to check, the result: 1 string produces sound 2 cents lower than others two. Is this reason of the "twang"? Do I need another tunning?
Thanks for any help,

TV

Hi TV: The string that is 2 cents different than the others likely is the source of your "twang." The way to tell is to silence the offending string with the tip of your finger, play the note, (actually playing the remaining two strings.) If the twang is gone, then you know it is caused by the string that is flat. You don't need a whole tuning, only the one string that is out of tune with its companions on F5. Ask your tech to stop in next time he is in the area and check it out. Be careful not to accuse or blame, as you really don't know the reason for the sour note. Be prepared to pay for a service call, but maybe not if it doesn't take long, or he is in a good mood. PNO2NER....

Every pianist should learn how to tune unisons. I intend to do this myself sometime in the next two decades.

Thanks PNOZNER and Palindrome for your advices.