How to tune a violin, viola, cello, or double bass

The pitches for each instrument

Three of the four orchestral strings are tuned in perfect fifths. The double bass is the exception, tuned in perfect fourths, because its strings are too long for a hand to span a fifth in one position.

The reference is the A above middle C at 440 Hz. Many orchestras tune slightly higher, to 442 Hz, for a brighter ensemble sound, and baroque groups often use 415 Hz, roughly a half step lower. If you are heading to a rehearsal, tune to whatever that ensemble uses, not to whatever your app defaults to.

Pegs and fine tuners do different jobs

A peg turns the string a long way for a small turn of your hand, it is for getting a string into the right neighbourhood. A fine tuner, the small metal screw at the tailpiece, moves the pitch by a few cents per turn and is for the last stage. Trying to make a five-cent correction with a peg is how beginners overshoot and snap strings.

Pegs work by friction, not by a mechanism, so they need inward pressure as you turn. Push the peg gently toward the pegbox while you rotate; if you only rotate, it will slip back the instant you let go. Turn in very small increments, an eighth of a turn changes the pitch considerably. Cellos and basses often have geared pegs or machine heads, which behave more like a guitar tuner and need no inward pressure.

The tuning sequence

1. Start with the A string and get it exactly right. Everything else will be checked against it.
2. Tune the remaining strings in order, moving away from the A, D, then G, then C on viola and cello; D, then G, then E on violin.
3. Approach every pitch from below. Tune slightly flat and come up to the target, so the string tension settles under the peg rather than easing back down.
4. Go around all four strings a second time. Bringing one string up to pitch changes the total tension on the top, which pulls the others slightly flat.
5. Finish with a check by fifths: bow two adjacent strings together and listen for the interval to lock, with no beating between them.

That last step is the one that separates a tuned instrument from an approximately tuned one. An electronic tuner reads each string against equal temperament; your ear reads the relationship between them. When both agree, you are genuinely in tune.

Tuning by ear, with and without a reference

Bow two adjacent open strings at once and listen. When the fifth is not quite in tune you will hear a slow pulsing, the beating between the two pitches. As the interval closes, the pulsing slows and then disappears. This is the same mechanism that makes double stops such a sensitive intonation test, and practising it on open strings builds the ear you will use for everything else.

In an orchestra, the oboe gives an A and the concertmaster passes it to the strings. In a rehearsal room with a piano, take the A from the piano. On your own, an electronic tuner or a reference tone is fine, but tune the A from the reference and the other three by fifths, rather than reading all four from the screen. It is faster, and it trains something.

When a string will not stay in tune

• Brand new strings stretch for several days and will go flat repeatedly. This is normal, retune as often as needed and it settles within about a week.
• A peg that slips is usually too dry. Peg compound, applied sparingly by a luthier or a confident owner, fixes it. A peg that sticks and jumps has the opposite problem and needs the same attention.
• Sudden changes in temperature or humidity move the pitch of every string, which is why an instrument taken from a cold car into a warm hall needs retuning after it acclimatises.
• A string that goes false, buzzing, or reading a different pitch in different positions, is worn out. Strings have a lifespan of roughly six to twelve months of regular playing.
• If the whole instrument has dropped dramatically and the bridge is leaning toward the fingerboard, straighten the bridge before tuning. A bridge pulled out of vertical by repeated tuning will eventually warp.

A tuner that shows cents rather than only a needle makes all of this easier to diagnose, because you can see whether a string is drifting a little or a lot. Arco's tuner is free, works in the browser, and has open-string reference tones for all four instruments.