Dan bau tuner (Vietnamese monochord)
The đàn bầu (độc huyền cầm) has a single steel string. The usual teaching and tuner setting is C3 = 130.81 Hz for the open string, an octave below middle C, with the flexible rod at rest. Tam Thi Pham's course at Hamburg Open Online University and the Vancouver Inter-Cultural Orchestra's notes based on Khắc Chí's teaching both give this pitch.
C-tuned đàn bầu: open string and harmonic positions
Đàn bầu tuned to C: open string C3, an octave below middle C, with the rod at rest. Positions I–VI are harmonics; equal-tempered frequencies at A4 = 440 Hz.
| Position | Note | Frequency (Hz) |
|---|---|---|
| Open string | C3 | 130.81 |
| Position I · 1/2 | C4 | 261.63 |
| Position II · 1/3 | G4 | 392.00 |
| Position III · 1/4 | C5 | 523.25 |
| Position IV · 1/5 | E5 | 659.26 (natural harmonic ≈ 654.1) |
| Position V · 1/6 | G5 | 783.99 |
| Position VI · 1/8 | C6 | 1046.50 |
Tam Thi Pham — Learning Dan Bau, Lesson 1 (Hamburg Open Online University)
How to use it
- Tap Turn on microphone, keep C3 or choose the tonic of your piece.
- Take your hand off the rod: the slightest touch changes the tension and the pitch.
- Pluck the open string without touching a node, and turn the tuning machine at the wide end until the needle centres. Always tune up to the note.
- Check with the half-string harmonic (position I): it should read C4, exactly an octave above the open string.
Help and explanations
Traditionally the open string is tuned to the tonic of the piece, so this page also offers D3, B2, B♭2 and A2. Each of those octaves comes from a single source, so C3 stays the default. Below A the string becomes too slack to speak well.
Harmonic positions on a C-tuned đàn bầu
The đàn bầu speaks mostly in harmonics: the edge of the right hand touches a node lightly while the short plectrum plucks. Measured from where the string meets the rod, the positions are I = 1/2 of the string (C4), II = 1/3 (G4), III = 1/4 (C5), IV = 1/5 (E5), V = 1/6 (G5) and VI = 1/8 (C6).
Vietnamese methods call these Đô 1, Sol 1, Đô 2, Mi 2, Sol 2 and Đô 3, counted from the open string, so they equal C4–C6 only when the open string is C3. Tuned to D, the series becomes D4–D6. The positions are not marked on the instrument: find them with the tuner, then mark where the plectrum strikes.
Harmonics are not equal-tempered
The notes follow the natural harmonic series. G (1/3 and 1/6) is about 2 cents sharp, E at position IV is about 14 cents flat of equal-tempered E5, and the 1/7 node gives a B♭ about 31 cents flat, which is why it is rarely used. Tune by the open string or the C harmonics (1/2, 1/4, 1/8), never by the E.
Notes bent with the rod, vibrato, pressed inflections and the Bắc and Nam modes are the player's choice; the tuner is only a reference.
Tips
- If the tuner shows C4 when you pluck the open string, it caught the second harmonic; what matters is the note C with near-zero cents.
- On an electric đàn bầu, hold the phone near the amp and switch off echo and reverb while tuning. On an acoustic one, hold it close to the body and gourd.
- Do not tune the open string up to C4: it needs about four times the tension, stiffens the rod and risks breaking the string.
Frequently asked questions
What note is a dan bau tuned to?
Usually C3 (130.81 Hz at A440) for the open string with the rod at rest. For a piece in another key, tune the open string to its tonic.
What are the dan bau notes on a C string?
The six harmonic positions give C4, G4, C5, E5, G5 and C6. Other notes come from bending the rod.
Why does the dan bau E read flat?
The fifth natural harmonic sits about 14 cents below equal-tempered E5. That is physics, not a tuning fault.
Can I tune a dan bau with my phone without an app?
Yes. Open the page, allow the microphone and pluck the open string. The audio is analysed in your browser.