Xianfa (弦法) names a jianpu relationship: which scale degree belongs to each open string. It does not mean six physical tunings. Inner D and outer A stay a perfect fifth apart; only their numbered roles change with the key.
01 The six common systems
Swipe sideways to compare both open strings.
| Key | Xianfa | Inner D string | Outer A string |
|---|---|---|---|
| D | 1–5 | 1 | 5 |
| G | 5–2 | 5 | 2 |
| F | 6–3 | 6 | 3 |
| C | 2–6 | 2 | 6 |
| A | 4–1 | 4 | 1 |
| B♭ | 3–7 | 3 | 7 |
The shorthand reads inner string first, outer string second. So 1–5 xianfa means the open D string is jianpu 1 and the open A string is 5. In 5–2, the same pitches function as scale degrees 5 and 2 in G.
02 Why one tuning supports six keys
Jianpu numbers are relative to the key centre. D is 1 in D major, 5 in G, 6 in F, 2 in C, 4 in A, and 3 in B♭. A is always a fifth above D, so its degree changes in parallel: 5, 2, 3, 6, 1, 7. The pitches stay put while their musical jobs change.
03 Choose the key line before reading a digit
A bare jianpu 1 is incomplete information. Read the key declaration — for example, 1 = D — then choose the matching xianfa. That tells you whether an open string can play the digit or whether the left hand must stop it.
04 Practise the open-string pair first
For each system, bow the inner and outer open strings while saying their two numbers aloud: 1–5, 5–2, 6–3, 2–6, 4–1, 3–7. Then add a short scale fragment. This separates a notation problem from an intonation problem before both arrive inside a piece.
05 Tuner mode and course mode serve different jobs
The tuner still targets physical D4 and A4 in every xianfa mode. The selected system changes degree labels, reference context, and lesson mapping — never the frequency of a correctly tuned open string. Soloist Erhu exposes all six systems in the free tuner and revisits them in graded course drills.
Related reading
Questions
What does 1–5 xianfa mean?
The inner D string functions as jianpu degree 1 and the outer A string as degree 5, the standard relationship in D key.
Do I retune the erhu for 5–2 xianfa?
No. Keep D4–A4 tuning; in G key those same open pitches function as scale degrees 5 and 2.
Which six xianfa systems does Soloist Erhu support?
D 1–5, G 5–2, F 6–3, C 2–6, A 4–1, and B-flat 3–7.