Cello Tuner — CGDA with Peg and Fine Tuner Guidance

A cello is tuned in perfect fifths to CGDA: C2, G2, D3 and A3 from the lowest string to the highest, with A4 = 440 Hz as the usual reference. The C string is the lowest note on the instrument and the one a microphone tuner reads least reliably.

How to use it

1. Start the tuner. Press Start Tuner (Microphone) and allow access. Nothing is recorded; everything runs in the browser.
2. Bow close to the bridge for the C and G. The low strings produce more fundamental there; move the contact point toward the fingerboard if the D and A sound thin.
3. Tune one string at a time with full bow strokes. A half-power bow leaves the low C under-developed, and the display wanders while the note builds.
4. Stop the other strings with a left-hand finger. The cello’s open strings ring under each other; a light touch is enough to damp them without pressing to the fingerboard.
5. Pegs first, tailpiece tuners last. A cello peg moves the pitch far with a small turn; once the string is near the note, finish with its fine tuner.
6. Come up to the note, never down to it. Ease the string below pitch and raise it again so the peg and the string settle under tension.
7. Bow pairs of adjacent strings for the fifths. C–G, then G–D, then D–A: a clean fifth has no beat. If a pair throbs, move the upper string of the pair.
8. Match the ensemble’s A before you begin. 440 Hz is the default; choose 442 when the group tunes there.

Cello string frequencies

On a cello the numbering starts at the player’s side too: the 4th string is the low C, and the numbers run up to the A on the 1st.

String	Note	Frequency (A4 = 440 Hz)
4th (lowest)	C2	65.41 Hz
3rd	G2	98.00 Hz
2nd	D3	146.83 Hz
1st (highest)	A3	220.00 Hz

Pegs and tailpiece fine tuners

• The pegs make the large changes. They are friction fittings in the pegbox, and a small turn moves the pitch a long way on a cello’s long strings. Use them after fitting new strings or when a string has slipped badly.
• The fine tuners make the small changes. Most cellos carry a tuner for every string on the tailpiece. They are the normal way to correct everyday drift, and they are why a cellist can tune quickly without touching a peg.
• Why the cello differs from the violin. Violins usually carry a fine tuner on the E string alone, because the steel E is the hardest string to set with a peg, and four tuners add weight at the tailpiece. Cello strings are longer and heavier, so the same small peg movement produces a bigger pitch change, and four tuners make the instrument practical to tune. The tailpiece also has the room for them.
• Fine tuners have limited travel. When one is screwed most of the way in it cannot sharpen the string further. Reset it and use the peg to bring the string near the note, then finish with the tuner.
• The C string’s peg is the stiffest. It carries the heaviest string on the instrument. Turn it with a gentle inward pressure so it stays seated, and never force it.

Checking intonation against harmonics

Harmonics are the cellist’s tuning aid as well as an ear-training tool. A lightly touched string at a node produces a clear, bell-like note with no bow noise, and the octave harmonic is the most useful of them.

• The octave harmonic sits at the midpoint of the string. Touch the string lightly exactly halfway between the nut and the bridge — where the 12th fret would be on a guitar — and bow with a light, fast stroke. The harmonic sounds one octave above the open string.
• The harmonic is usually steadier than the fundamental for a microphone. It is a pure, sustained tone with less of the low string’s decaying energy. For the C string, the octave harmonic is C3 = 130.81 Hz, an easier pitch for a small microphone to read than C2.
• Compare the harmonic with the stopped note at the same point. If the harmonic and the note you stop at the midpoint disagree, either the stopped note is misplaced or the instrument’s setup needs attention. The comparison is a pitch check that works by ear even when the display is unsure.
• Tune the fifths by bowing adjacent strings together. A pure fifth has no beating. If you hear a slow pulse, one of the pair is off; adjust the upper string until the pulse stops.
• Use the octave harmonic as an ear check for the low C. The open C is an octave below the harmonic, so if the harmonic is right, the string is in the right octave.

The cello and the double bass

The two large bowed strings are easy to confuse from a distance, but they are different instruments with different tunings:

	Cello	Double bass
Tuning	CGDA, in fifths	EADG, in fourths
Lowest string	C2 (65.41 Hz)	E1 (41.20 Hz)
Written pitch	Sounds as written	Sounds an octave below written
Played	Seated, between the knees	Standing or seated, on the floor

• The tunings move in different intervals. The cello tunes in perfect fifths, like the violin and viola. The double bass tunes in fourths, like a bass guitar, which is why a bass player’s finger patterns feel different from a cellist’s.
• The bass’s lowest string is lower than the cello’s. E1 at 41.20 Hz sits below the cello’s C2 at 65.41 Hz, even though the cello’s C is the lower note name.
• The bass is a transposing instrument and the cello is not. Double bass music is written an octave above the sounding pitch; cello music is written where it sounds.

A442 and other references

Most orchestras hand you an A at 440 Hz; some — especially in Japan and parts of continental Europe — push it to A442, and period-instrument bands may go as low as A415 or A430. Select the matching chip rather than retuning the instrument to a mismatched reference.

• A442 raises every target by about 0.45 %. The strings stay in perfect fifths; the whole instrument sits slightly higher.
• Set the chip before the first bow stroke. If the tuner still says 440 and the orchestra is on 442, every string will read flat no matter how carefully you tune.
• Confirm the pitch with the conductor or ensemble manager. Guessing between 440 and 442 wastes warm-up time; the answer is usually one question away.

Accuracy and limits

• The C string is the lowest note here, and low strings are where a microphone reading is least certain. Treat the C string’s reading as approximate, check it against the octave harmonic, and expect the G, D and A strings to settle faster.
• The low C takes a moment to speak. Bow it with a long, even stroke and let the note develop before you judge the display. A short or hesitant bow gives the detector too little to work with.
• Jumping to C3 mid-bow? The overtones won. A microphone on a cello often hears the harmonic series more strongly than the C2 fundamental, so the display can sit an octave high. Steady the bow and match what you see against the C2 card.
• A full section is a hard room for any microphone. Cellos are loud and their open strings ring together. Tune before the section fills up, or one instrument at a time.
• The cello is too large to hold against the microphone. Rest the device on a music stand close to the instrument, or have someone hold it, rather than trying to bow and hold a phone at once.
• Pizzicato gives a shorter reading. The note dies quickly, so pluck again while watching the display instead of trusting one frame.
• Temperature and humidity move the instrument. Cellos drift with the weather, and pegs can slip in dry conditions. Tune, play for a few minutes, and come back to it — a cello carried through a cold corridor will keep moving.
• A uniform flat reading is a reference problem. Four strings do not drift by the same amount at once; check the A chip before touching a peg.

Safety

• The bridge is held by string tension and the soundpost by friction. Never take all four strings off at once; replace them one at a time so the bridge and soundpost stay in place. A fallen soundpost is a luthier’s job.
• Pitch up in small increments. The wound C carries the most tension and the A is the most delicate; move the peg a little and recheck.
• Never force a peg. A peg that will not turn is binding. Forcing it can crack the pegbox or break the string; ease it free instead.
• The low C target is C2 = 65.41 Hz. Tuning it an octave up would roughly double the tension the instrument and string are made for.
• Fine tuners run out of travel. If the screw stops sharpening, loosen it, set the string close to pitch with the peg, and use the tuner only for the last adjustment.
• After tuning, check that the bridge still stands square. A bridge that has tipped forward needs the string tension eased before it is nudged back — or a repairer’s hands.
• Secure the endpin and support the instrument. A cello is heavy and awkward; tune it properly seated between the knees with the endpin firm, not balanced against a chair leg.
• Protect your hearing. A cello played close is loud. Take breaks during long tuning and practice sessions.