Open Piano Tuner

How it works

The wizard follows Defenbaugh's F to F temperament as given in Reblitz's book¹. Our reading of its steps is in Defenbaugh.md².

1. Survey the strings. Strike each of the 14 temperament notes once. A piano string's overtones sit a little sharp of exact multiples of its fundamental³, and the survey measures by how much, so the beat targets fit your piano.
2. Tune the 14 book steps. One note at a time, the wizard shows the beat of the interval you are tuning against its target and says whether to raise or lower the note, until the beat is right.
3. Check the thirds and sixths. A final test compares the inside thirds with the outside sixths, as the book does, to confirm the temperament is even.

The Sound explorer finds the notes in a sound with Klapuri's method for hearing several pitches at once⁴.

Notes

1. Reblitz, Arthur A. Piano Servicing, Tuning, and Rebuilding, 3rd ed. Vestal Press, 2019. The Defenbaugh F to F temperament sequence. Back
2. The project's own summary of the sequence, in its own words: Defenbaugh.md in the repository. Back
3. Fletcher, H., Blackham, E. D., Stratton, R. "Quality of Piano Tones." Journal of the Acoustical Society of America 34(6), 1962. String inharmonicity: f_n = n f₀ √(1 + B n²). Back
4. Klapuri, A. "Multiple fundamental frequency estimation based on harmonicity and spectral smoothness." IEEE Transactions on Speech and Audio Processing 11(6), 2003. ieeexplore.ieee.org/document/1255467. Back