This leads to the phenomenon of 'stretch' - the octaves on a well-tuned piano are actually wider than they theoretically should be. When a piano tuner is putting the instrument into tune, (s)he is actually matching the overtones of lower notes to the fundamental pitch of higher notes. However, because a piano string is slightly stiff and not perfectly flexible, the overtones actually end up being slightly higher in pitch than they theoretically should be. Thus, A below middle C, which should have a frequency of 220Hz at standard pitch, will also produce overtones at 440Hz, 660Hz, 880Hz and so on. When a string vibrates between two fixed points, it vibrates separately through portions of its length (whole, half, one third, one quarter, one fifth and so on), which create additional tones (called overtones or partials) in addition to the fundamental frequency. This isn't because of any fault with the tuner itself - rather it's because of the way piano strings behave. This is the only piece of electronic equipment I have.Īfter this, the electronic tuner has done its job and gets put away - it can't be used to tune a whole piano - and I complete the entire remainder of the tuning by ear. I use it to set the first string when tuning a piano, to check the piano is on pitch (although I can tune to a fork, it takes a little longer). In my opinion it's one of the best chromatic tuners out there.

The picture above is of a Korg OT-120 chromatic tuner, which I'm 'testing' with a tuning fork.

Digital piano tuner