Cello tuner

Standard cello tuning, from the 4th string to the 1st: C G D A. Frequencies are for A4 = 440 Hz.

Cellists tune the A string first, then D, G and C, each a fifth below the one before. Set the endpin in a rock stop or on a spot where it won't slide, so the cello stays put while one hand turns and the other bows. A cello that shifts on the floor makes a steady bow stroke hard, and a steady stroke is what the tuner needs.

Give the tuner a long tone: a slow, full bow with even weight. The low C, at 65.41 Hz, takes a moment for the needle to settle, so keep bowing for a couple of seconds rather than reading the first instant. Plucking works too, but a plucked cello note fades before the needle has much time.

Tune slightly below each note and come up to it. Cello strings are long and heavy; if you overshoot and loosen back down, the string can slip on the peg and drift flat while you play.

The four pegs hold by friction, like a violin's, but they are larger and take more force. Turn a peg with a slight push into the pegbox so it grips, and use the pegs only when a string is far from pitch or has just been changed.

Fine tuners on all four strings are common on cellos, not only on student instruments, because many cello strings have steel cores and move a lot with a small turn of the peg. Use them for the last few cents. If one runs out of thread, unscrew it to the middle and bring the string up with the peg instead.

Change strings one at a time and tune each new one up before you take off the next. With all four slack at once, the bridge can fall, and the soundpost inside the body can drop with it; setting a soundpost back is a job for a luthier. A new string also stretches for several days, so expect to tune it more often than the others.

The cello is tuned C G D A, the same letters as the viola one octave lower. Its open C is the lowest note of the string section apart from the double bass, and it speaks more slowly than the upper strings: use a heavier, slower bow and let the note bloom before you judge it.

A classic by-ear check uses harmonics. The harmonic a third of the way up the D string and the harmonic halfway up the A string are the same note, the A an octave above the open A string. Play them together: if they beat, the two strings are not yet a clean fifth apart.

Fifths tuned by ear are pure, about 2 cents wider than the tuner's equal-tempered fifths. Three of them add up: tuned in pure fifths down from the A, the C string ends up about 6 cents below the tuner's C, just outside the green zone. When you play with a piano, trust the tuner or keep the fifths a touch narrow.