12-String Guitar Tuner Online — Octave Pairs

A 12-string guitar has six courses tuned to standard EADGBE, with two strings per course. Courses 6–3 (E, A, D, G) are octave pairs, and courses 2 and 1 (B, E) are unison pairs. The tuner’s cards show the primary pitch of each course; the partner string matches an octave above or in unison.

How to use it

1. Start the tuner. Press Start Tuner (Microphone) and allow microphone access. The audio is analysed in your browser; nothing is uploaded.
2. Tune in two passes. Get all twelve strings roughly in tune first, then fine-tune. Every string you tighten pulls the neck and shifts the others, so a single pass from one end to the other will not hold.
3. Work course by course, from the sixth course up. Tune the primary string of the course to the card, then tune its partner to the same card — an octave above on courses 6 to 3, at the same pitch on courses 2 and 1.
4. Keep the octave straight. On the sixth course the card is E2 = 82.41 Hz and the partner is E3 = 164.81 Hz. Check which string is in your hand before you turn the peg; the partner strings on the bass courses are thin plain strings next to heavy wound primaries.
5. Mute the other courses while you work. A 12-string rings sympathetically more than a six-string. Rest the side of your hand across the unused courses and pluck one course at a time.
6. Pluck a single string when the reading is ambiguous. A course sounds both strings at once, so the display can report the partner’s octave instead of the primary’s. Picking one string of the pair gives an unambiguous reading.
7. Re-check after a few minutes. Twelve strings settle slowly, and the octave strings drift first.

Course-by-course frequencies

The cards show the primary pitch of each course. The partner column is what the second string of the course is tuned to, one octave above the primary on courses 6 to 3, or in unison on courses 2 and 1.

Course	Primary string	Primary frequency	Partner string	Partner frequency	Pairing
6th (lowest)	E2	82.41 Hz	E3	164.81 Hz	Octave
5th	A2	110.00 Hz	A3	220.00 Hz	Octave
4th	D3	146.83 Hz	D4	293.66 Hz	Octave
3rd	G3	196.00 Hz	G4	392.00 Hz	Octave
2nd	B3	246.94 Hz	B3	246.94 Hz	Unison
1st (highest)	E4	329.63 Hz	E4	329.63 Hz	Unison

Why the bass courses are octave pairs

• The low courses need brightness. E2, A2, D3 and G3 sit at the bottom of the guitar’s range, where a single string can sound dark. Adding a string an octave above gives each of those courses a bright upper voice without changing the chord.
• The top two courses are already high. Pairing B3 and E4 in octaves would put the top of the instrument at B4 and E5, an octave above the top of a standard guitar. Keeping them in unison leaves the top end where it is.
• Unison pairs still thicken the sound. Two strings at the same pitch reinforce each other, so the top two courses sound fuller than single strings even though they do not add range.
• The result is a balanced instrument. Octave pairs fill in the middle of the register while unison pairs keep the top from becoming thin and overstretched.

Tuning order and tension

• Primary first, partner second. On an octave-paired course, the primary is the heavier string and the partner is much thinner. Bring the primary to its card, then the partner to the octave above.
• Bring the instrument up in stages. Tune every course roughly, then go around again. This keeps the neck from being pulled hard to one side while the other strings are still slack.
• Expect a lighter set for a reason. Twelve strings carry far more total tension than six, which is why 12-string sets use lighter gauges than standard six-string sets. Do not fit a heavy six-string set and tune it to pitch.
• Watch the bridge and the top. A 12-string’s extra tension is real. If the bridge starts to lift or the top bellies, stop and have the instrument looked at.
• Retune after playing. The thin octave strings stretch and settle, and the primaries move as the neck relaxes.

Accuracy and limits

• A course sounds two strings at once. The display reports the strongest periodic signal it receives, so on an octave-paired course it can show the partner’s octave rather than the primary’s pitch. The note name will be right either way — the octave may not be. Pluck a single string of the course when the octave matters, and compare against the card.
• Unison pairs can beat against each other. If the two strings of course 2 or 1 are slightly apart, the combined sound wobbles and the display can drift with it. Tune one string to the card, then bring the other in until the wobble slows and stops.
• The low E course is the microphone’s weak point on this instrument. E2 = 82.41 Hz sits in the region where small laptop and phone microphones are least sensitive, and the course’s heavier primary speaks more slowly than the strings above it. Pluck it firmly, mute the other courses, and hold the note before judging the reading.
• The octave strings are thin and quiet. They are easy to under-pluck, which leaves a weak signal the detector has to work with. A clean, even pluck gives a better reading than a hard one.
• A capo rewrites every course. With a capo fitted, all twelve strings sound above the pitches on the cards. Tune with the capo off, then fit it and expect the reading to sit sharp by design.

Safety

• Never tune a string an octave above its target. The octave strings are thin and the bass primaries are heavy; the wrong octave is how strings break. Know which string of the course is in your hand before turning the peg.
• Tune up to pitch in small increments. If a string is sharp, lower it below the target and bring it back up rather than stopping on the way down.
• Do not force a stiff peg. A string that binds in the nut slot should be eased free, not forced, especially on the thin octave strings.
• Respect the extra tension. Twelve strings pull much harder than six. Use a set made for a 12-string, and have the instrument checked if the top or bridge shows any sign of lifting.
• Give new strings time. Fresh strings stretch for the first minutes of playing, and twelve of them stretch at different rates. Tune, play briefly, then re-check.
• Check the whole instrument after tuning. A string that will not hold pitch, or a buzz that appears in one position, is a setup issue rather than a tuning one.