One Note Out of Tune on Your Piano

You've already decided this is a tuning problem, and you're pricing tuners. Test that assumption before you spend anything, because two of the six things that make a single note sound sour will sound exactly as sour after a technician has tuned the piano and driven away.

"One note out of tune" is not a diagnosis. It's a symptom, and it has at least six mechanical causes underneath it, running from free to a rebuild. A fine tuning from Ron Bergeron, RPT, at PianoWorks in Round Rock, Texas runs $230 plus tax. Willey Piano Tuning in Renton, Washington lists $240. If what you've got is cause number four below, you can hand over that money and the note will sound the same when the technician packs up. Prices checked August 2026.

So let's find out which one it is. Five of the six you can screen yourself at the keyboard, with your hands and about ten minutes.

The one thing that separates the causes: the mute test

Almost every note above the low bassBassThe lowest part in a musical composition. It provides the harmonic foundation upon which the melody and inner voices are built.The Savvy Take: Amateur pianists listen to the melody; pros listen to the bass. If your bass line is weak or timid, the entire harmonic structure collapses. Play your bass notes with confidence—they are the floor the rest of the music stands on.View in glossary → is struck by two strings (a bichord) or three (a trichord) tuned to the same pitchPitchThe perceived highness or lowness of a sound, determined by the frequency of vibration.The Savvy Take: Most people have “Relative Pitch” (recognizing intervals), not “Perfect Pitch.” And that’s fine! Relative pitch is actually more useful for understanding harmony and structure.View in glossary →. That group is called a unisonUnisonTwo or more voices or instruments sounding the same pitch (or octaves of the same pitch) simultaneously.The Savvy Take: Playing in unison with both hands is deceptively hard. If your left hand is 1 millisecond slower than your right, it sounds “flammed” and amateur. Practice strictly together to get that laser-focused sound.View in glossary →. Sally Phillips, writing in Piano Buyer, puts the requirement plainly: every string in a unison must be beatless relative to each other.

The test is to silence some of those strings and listen to what's left. A technician slides a rubber wedge mute between the strings, plays the note, and knows within seconds whether the problem lives in one string or between them. It takes about four seconds and it's the first thing I do when I walk in the door.

Say this on the phone when you book: "Can you mute the unison before we talk about tuning?" If the piano is due for a tuning, it's due either way. What that question buys you is a chance to skip paying for a tuning that was never going to fix the note.

1. Unison drift (the boring answer, and usually the right one)

One string of the three has wandered a few cents off its partners. The frequency difference between them produces a beatBeatThe basic temporal unit of a composition. The regular pulse that organizes the rhythm.The Savvy Take: There is a difference between “keeping time” and “feeling the beat.” A metronome keeps time; a musician feels the pulse. Your job is to internalize that pulse so strongly that you can push against it (rubato) without losing it.View in glossary →, the wah-wah-wah you're hearing as wobble, chorus or honky-tonk. Nothing is broken and nothing is wrong with your piano.

How you tell: the note beats against itself. Play it alone and let it ring. You hear a single pitch pulsing at a steady rate, a few beats a second. Play the half stepHalf StepThe smallest interval in the standard Western scale (e.g., C to C#). Also called a semitone.The Savvy Take: Half steps are the source of all tension. The leading tone wanting to resolve to the tonic? That’s a half step. The scary theme in Jaws? Half steps. If you want to create drama, use half steps.View in glossary → above and the half step below, and those ring clean. It's most common in the trichord treble where three strings are involved.

Cost: nothing extra. Any technician folds this into a tuning visit as a matter of course. If it's your only complaint and you don't want a full tuning, ask about a minimum service call. Bergeron lists $115 plus tax minimum for a non-tuning service call, covering the first thirty minutes.

2. A string that slipped at a bearing point

Each string turnsTurnAn ornament consisting of four notes: the note above, the main note, the note below, and the main note again.The Savvy Take: A Turn is like drawing a circle around a note. It decorates the pitch. Don’t rush it so much that it sounds like a glitch; it should be a graceful curl.View in glossary → corners on its way from the tuning pin coil to the V-bar or agraffe, across the bridgeBridgeA transitional passage connecting two sections of a composition, or the contrasting B section in a standard AABA song form.The Savvy Take: In pop and jazz, the Bridge is the energy booster. It usually lifts the harmony to a new place (often the IV chord). Don’t let the energy drop here; it should build tension that makes the return to the final verse (A section) feel satisfying.View in glossary → pins, down to the hitch pin. Friction at those corners means the segments can sit at different tensions. Technicians equalize that during a tuning, a step called string rendering. Sometimes a hard blow lets a segment go and the speaking length changes pitch in an instant.

How you tell: you remember when it happened. There was a small tink or ping, and then that note was flatFlatThe symbol (b) indicating that a pitch should be lowered by one semitone.The Savvy Take: Visually, flats look “heavy” (like a sagging belly). Musically, they often sound mellower or darker than sharps. When a piece modulates to the flat side, think of it as a relaxation or a darkening of the mood.View in glossary →. No humidity swingSwingA rhythmic feel in which paired eighth notes are played unevenly — long-short, leaning toward a triplet subdivision — rather than straight.The Savvy Take: Don't do the math; do the listening. Swing is a feel with a dial, not a formula — lock your comping into a great ride-cymbal pattern (or a Basie record) and your hands will find the ratio your ears already know.View in glossary →, no move, no season change. On the Piano World thread about a Petrof upright whose D-flat went twangy after an audible tink, Mark Cerisano, RPT, put it on the string slipping at the V-bar; Ed McMorrow, RPT, thought the hitch pin loop had moved. The owner's technician neighbor fixed it in thirty seconds and found no damage.

Cost: a minimum service call, $115 plus tax for a non-tuning visit covering the first thirty minutes, or roughly $75 an hour on Willey Piano Tuning's published repair rates. Most technicians will catch it at your next tuning if you ask.

3. A tuning pin that's not holding

Each string winds onto a steel pin driven into a laminated maple pinblock, and the pin holds by friction. New York Piano Works puts freshly pinned pianos at a torque of 120 inch pounds or more, with slipping starting when torque drops below 20 or 30. A pin that loose creeps backward under 150-plus pounds of string tension, and that string goes flat again weeks after you paid to have it tuned.

How you tell: keep a record. Put it in your phone. Date tuned, date that key went sour again. If it's always the same key and always within days or a few weeks while the restRestA symbol indicating silence for a specified duration.The Savvy Take: Music is painted on a canvas of silence. The rests are as important as the notes. Don’t rush through them! A sudden silence (Grand Pause) is often the loudest moment in the piece.View in glossary → of the piano holds for months, that's a pin. Weather moves whole sections of a piano together, never one key over and over. (If you want the background on why the whole instrument moves seasonally, that's why pianos are never in tune and how to protect your piano during winter.)

Cost: a single pin replacement is a small line item, but Austin's Piano Service calls a defective pinblock a majorMajorReferring to a scale or chord containing a major third. In Western music, usually associated with brightness, stability, or happiness.The Savvy Take: Don’t play Major keys as just “happy.” They can be triumphant, calm, nostalgic, or regal. A C Major chord played pianissimo is very different from one played fortissimo.View in glossary → contributor to tuning instability, and one loose pin is often the first symptom of a block that's going. Whole-block treatments get quoted case by case. Get the number in writing.

Ask whether your technician carries a pin torque wrench. Plenty don't bring one on a house call, and the ones who do can hand you a reading in inch pounds to set against that 120.

4. A false beat (the one tuning can't cure)

A single string can beat all by itself with no second string anywhere near it. Brian Capleton, in the Journal of the Acoustical Society of America (115(2), 2004), traced it to the string's partial being radiated from a pair of closely spaced modes, because the string is terminated differently in the vertical and horizontal planes. His paper allows two other possible causes of false beats: nonuniformity in the string, and torsional stress. Rust and old liquid spills get blamed for it around the shop, though that's trade lore, and his paper doesn't claim it.

How you tell: this is what the mute test was invented for. Isolate one string and it still pulses on its own. Capleton, verbatim: "the false string, if sounded on its own by muting the other strings with a wedge, still exhibits the false beat." Unison drift vanishes the moment the strings are separated. A false beat survives it. Second tell: the note gets tuned, sounds perfect for a moment, and never settles. Third tell: it lives in the top two octavesOctaveThe interval of an eighth. Two notes with the same letter name, where the higher note has exactly twice the frequency of the lower.The Savvy Take: Tension is the enemy of octaves. If you stiffen your wrist to reach the distance, your sound will be harsh and your arm will hurt. Keep a “bouncy” wrist and grab the octave with a quick, loose motion.View in glossary → more often than anywhere else, because Capleton shows a 0.1 mm variationVariationA technique where material is repeated in an altered form (changes in harmony, melody, rhythm, etc.).The Savvy Take: When playing Variations (like Mozart or Haydn), you must characterize each one. Variation 1 might be “The Dancer,” Variation 2 might be “The Soldier.” Give each one a distinct personality.View in glossary → in speaking length is worth about 1/40 Hz at middle CMiddle CThe C nearest the middle of the keyboard — C4, about 261.6 Hz — and the meeting point of the treble and bass clefs on the grand staff.The Savvy Take: It's the middle of the notation system, not quite the middle of the piano (the true center of an 88-key keyboard falls between E4 and F4). Either way: it's the anchor every beginner method builds from, and the landmark your eyes should snap to.View in glossary → and about 5 Hz at C88.

Cost: a treble string replacement runs about $50 installed on Willey's list, $30 each when several are done at once. Bass is another animal. Bergeron lists individual bass strings at $140 installed for a universal replacement and $160 for one custom wound to your piano's scaleScaleA series of tones ordered by pitch (usually rising or falling) according to a specific scheme of intervals (e.g., Major, Minor, Chromatic).The Savvy Take: Scales aren’t punishment; they are vocabulary. 90% of classical music is just chunks of scales. If you know your scales by heart, you aren’t reading “C-D-E-F-G,” you’re just recognizing “C Major Scale chunk” and playing it on autopilot.View in glossary →. Howard Piano Industries, who make them, say the custom strings take one to two weeks to have made and shipped. The wire by itself is cheaper. Howard Piano Industries sells a custom-wound bass string as a part for around $40, which is the number you'll see quoted online with no labor attached to it.

Be told this before you pay: a new string can beat too. When the fault lives in the termination and the wire was innocent, the replacement does the same thing. A skilled tuner can often hide a mild false beat inside a trichord, and a severe one resists any unison adjustment there is.

And don't hand this one to a phone app. Electronic tuning devices read one composite pitch, and pianohistory.info notes that some of them do not know what to make of a false note.

5. Bridge trouble (technician only, no exceptions)

Where the string crosses the soundboardSoundboardThe large spruce panel under the strings (grand) or behind them (upright) that amplifies string vibration — effectively the piano's speaker.The Savvy Take: Hairline soundboard cracks look scary and are usually cosmetic; what matters is whether the ribs are tight and nothing buzzes. Its real enemy is humidity swing — which is why technicians never stop talking about it.View in glossary → bridge it's drafted sideways past a bridge pin, and that pin is the horizontal termination. Ron Nossaman on the pianotech list: "the pin is the termination, not the notch." Capleton, on p. 887, describes high tension against a small pin pressurizing the wood around the hole, with older instruments developing very small splits there. Stuart Davidson says loose bridge pins produce buzzing and false beats that cannot be resolved through tuning alone. Phillips says the same thing: insecure termination makes strings sound out of tune even when they've been tuned as well as possible.

How you tell: sourness plus lost tone. Play the sour note and its neighbor back to back and listen to how long each rings. If the sour one dies faster, sounds thin, dull or buzzy, and a muted single string still beats, the bridge is a live suspect. (If the note sounds harsh but rings normally and holds pitch, you're in voicing territory instead.)

Confirming it takes magnification on the bridge cap, hunting hairline splits at the pin holes. That's a bench inspection. You can't do it from where you're sitting. Davidson's rule: epoxy is the usual repair for small cracks, and severe cases need a new bridge cap. Generally only worth doing on a valuable piano. No published per-note figure exists for this work in the home. Every source treats it as a quote.

6. The coin on the soundboard

A single note excites everything in the room that happens to resonate at its frequency. A coin on the soundboard. A loose lid hinge, a music desk, a plate screw, a lamp on the case, a picture frame on the wall behind an upright. The note is at pitch. The noise riding on it is what your ear is calling sour. Piano Finders lists a rubbing damper wire, a groove in the capo d'astro bar, insufficient bearing at the agraffe holes, and a too-live duplex as internal buzz sources, and Kendall Ross Bean's whole method there is systematic diagnosis before any repair, because the noise almost never starts where you think it does.

How you tell: play the note and, while it rings, press a fingertip on the music desk, then the lid, then the fallboard, then the case sides, one at a time. When the noise stops, you found it.

Then take your hands off the piano entirely. Leave the sustain pedalDamper PedalThe right pedal: it lifts all the dampers off the strings, letting played notes ring and every other string vibrate sympathetically. Also called the sustain pedal.The Savvy Take: Pedal with your ears, not your foot. The core technique is syncopated pedaling — the pedal changes just after each new harmony sounds, so the join is seamless but never smeared.View in glossary → up so every damper stays on its string, and play that same pitch through a phone speaker set near the instrument. The piano can't sound, so anything you hear rattling is in the room. Do it with the pedalPedalA device on the piano operated by the feet. The right pedal (Damper/Sustain) lifts all dampers, allowing strings to vibrate freely. The left (Una Corda) softens the tone. The middle (Sostenuto) sustains only selected notes.The Savvy Take: Foot technique is as important as finger technique. Don’t just stomp it down. “Flutter pedaling” (rapid, shallow movements) can clear out the mud while keeping the sound warm. Pedal with your ears, not your foot.View in glossary → down and you've undamped all 200-odd strings, which turns the piano into the thing you were trying to rule out.

Cost: $0. That's a coin or a hinge screw, and you fix it yourself.

What NOT To Do (The Danger Zone)

Do not put a lever on a tuning pin. The head of a tuning pin is a tapered oblong, and the star-shaped socket in the tip of a tuning hammer has to seat on it square. A worn tip, or a socket the wrong size, rounds the head off and makes that pin unturnable by anybody afterward, including me. That's how a $230 tuning turns into a repinning quote.

Do not turn the wrong pin. The pins for a given note sit in an order you won't guess. You mute a string, put the lever on the pin you think feeds it, hear no pitch change (because you're tightening the muted one), keep turning, and snap it. This is the specific failure that breaks strings, and it happens to beginners constantly.

Do not jerk the hammer. The pinblock is laminated wood under load. Levering the tool instead of moving it in small controlled amounts can crack it, and a cracked block turns one sour note into a piano that holds no tuning at all.

Do not crank an old rusty string up to pitch. Oxidation builds between the wire and its bearing points so the string catches instead of sliding. Pitch raisesPitch RaiseA preliminary rough tuning pass performed when a piano has drifted well below pitch, done before the fine tuning in the same visit.The Savvy Take: Adding tension to 200-plus strings makes the first ones you tuned drift as the frame settles — so a badly flat piano needs two passes, and the tuning will be less stable for a while. The cheapest fix is not letting it get that flat: tune on schedule.View in glossary → on long-neglected pianos are where strings break, and in the bass that mistake costs $140 to $160 and a wait of a week or two while the string is wound.

Do not spray WD-40 or household oil on strings or pins. It migrates into felt and wood, it does nothing for tension distribution, and it contaminates parts that then need replacing. Technicians who lubricate use a purpose-made product like ProTek CLP, on action centers, bushings and capstans.

Do not tap bridge pins sideways to kill a buzz. Bean's warning at Piano Finders: it may work temporarily and it enlarges the pin holes. You convert a repairable buzz into a permanent false beat.

Do not put a jar of water or a wet sponge in the piano because one note started drifting. It doesn't raise humidity meaningfully, it's unregulated, and gravity is not your friend. If humidity is the real issue, install a real system. Willey lists humidity-control installation at $320 for an upright and $370 for a grand, and there's more on how those work in the Piano Life Saver system explained.

Do not keep re-tuning the same note. If it goes sour within days of every visit, you're paying repeatedly to correct a symptom while pin torque keeps dropping. Two visits a year is normal maintenance. If one key is pulling you back a third and fourth time, price the pin work instead.

The Savvy Verdict

Causes 1, 2 and 3 are ordinary and a technician handles them inside a normal visit. Cause 6 you fix yourself with a fingertip and a coin. Causes 4 and 5 are the ones worth knowing about before you spend, because tuning is the wrong tool for both and the second one needs a bench inspection to confirm. Terms like agraffe, capo bar and let-off all live in the music glossary if you want to look one up mid-conversation.

Before you book anything, get a wedge mute under that unison. Everything you'd be paying $230 to find out is on the other side of that four-second test.