1: Tune a single string from a single note in the middle octave.
2: Match the remaining strings in the note to the one first tuned.
3: Use the first octave to tune the others by ear.
The following table lists the beat frequencies between
notes in an equal temperament octave. The
top row indicates absolute frequencies of the pitches; usually only A440 is
determined from an external reference. Every other number indicates the beat
rate between any two tones (which share the row and column with that number)
in the temperament octave. Begin
by tuning one note to the other so that the beating disappears, temper that
interval in the appropriate direction (either making the interval wider or
narrower, see further below) until the desired beat rate is achieved. Slower
beat rates can be carefully timed with a metronome, or other such device. For
the thirds in the temperament octave, it is difficult to tune so many beats
per second, but after setting the temperament and duplicating it one octave
below, all of these beat frequencies are present at half the indicated rate in
this lower octave, which are excellent for verification that the temperament
is correct. One of the easiest
tests of equal temperament is to play a succession of major thirds, each one a
semitone higher than the last. If equal temperament has been achieved, the
beat rate of these thirds should increase evenly over the range of the piano.
This next table indicates the pitch at which the strongest beating should occur for useful intervals. As described above, when tuning a perfect fifth, for instance, the beating can be heard not at either of the fundamental pitches of the keys played, but rather an octave and fifth (perfect twelfth) above the lower of the two keys, which is the lowest pitch at which their harmonic series overlap. Once the beating can be heard, the tuner must temper the interval either wide or narrow from a tuning that has no beatings.
Piano tuning
is the act of making minute adjustments to the tensions of the strings of a
piano to properly align the intervals between their tones so that the
instrument is in tune . The meaning of the term in tune in the context of
piano tuning is not simply a particular fixed set of pitches . Fine piano
tuning requires an assessment of the interaction among notes, which is
different for every piano, thus in practice requiring slightly different
pitches from any theoretical standard. Pianos are usually tuned to a modified
version of the system called equal temperament ( see Piano key frequencies for
the theoretical piano tuning ). In all systems of tuning, every pitch may be
derived from its relationship to a chosen fixed pitch, which is usually A440 .
The primary strategy is to keep the environmental conditions as consistent as possible. Minimize changes in temperature and humidity; avoid placement near sunlight, windows, heating ducts, etc.
After that, the best way to keep your piano in tune is to (surprise!) tune your piano. Once the piano is in tune, it is easier to keep it in tune with touch-ups and regularly-scheduled tunings.
Don't wait until you can't stand the sound anymore. The more strings left untuned, the more the tension changes on the soundboard, causing a cascade effect where more and more strings to go out of tune.
The typical recommendation is to do a complete tuning twice a year, shortly after the heating and cooling seasons begin.