72 strings, 18 courses, and one fact that governs the session
A Persian santur is 72 strings in 18 courses of four — nine courses riding over the yellow bridges and nine over the white — and the string count is not the interesting part. This is:
A course crosses its bridge and sounds on both sides of it, so one peg moves two notes. One string, one peg, one bridge sitting on it. Tighten the peg and the pitch to the left of the bridge and the pitch to the right of it both go up together. The interval between the two sides is set by where the bridge stands — on the white bridges it is a fifth — and no amount of turning the peg will change it.
This is why 18 courses give roughly 27 playable pitches, and why a santur tuning session is not a list of notes you walk down. Every correction propagates. If a note is flat and its partner across the bridge is fine, the peg is not the answer.
Why this page has no target notes
Every other tuner on this site docks a row of target chips under the dial. This one does not, deliberately.
A santur’s pitch set is the dastgah. The instrument is tuned for the mode being played, and moving between modes means physically retuning two or three courses — often by a quarter tone rather than a semitone, which is a small enough move that it is done between pieces rather than between concerts. There is no standard 27-note chart to show you, and a chip bar would have to pick one kook and then be wrong for everything else on the programme. Inventing that would be inventing a fact.
So the tool here is the plain chromatic dial with its cents readout, which is the correct instrument for the job: it names whatever it hears and tells you how far from a semitone you are, which is precisely the number you are setting when you place a neutral degree. What it cannot tell you is what that number should be — see tuning systems for why the size of a Persian neutral second is a range rather than a value, and how much it moves between performers and schools.
The layout, in the order it matters
Facing the instrument, the yellow (right-hand) bridges carry the low register and the white (left-hand) bridges the middle, with the strings to the right of the white bridges giving the top. Nine courses on each side, four strings to a course, one tuning pin per string on the right-hand pin block.
Two consequences for the person holding the key. First, the pins are dense — closer together than any peg on any other instrument here — so the commonest physical error is turning the pin next to the one you meant, and the commonest symptom is a note going wrong that you were not touching. Second, the santur has no gearing at all: the key is a lever on a friction pin, so the smallest controllable movement is far larger than on a machine head. Approach every note from below and let the pin settle.
Tuning routine
- Pick the level first. A santur under full tension is holding a lot of load, and moving all 72 strings to a different pitch is not a small operation. Find where your instrument sits, set concert A to match, and work from there rather than dragging the whole thing to 440.
- Do one course completely before moving on. All four strings, both sides of the bridge, beat-free with each other. A half-finished course is worse than an untouched one because it will not tell you whether the next course is right.
- Damp to read. Three fingers or a felt wedge across the other strings of the course, so the dial hears one string. A four-string unison presents a tuner with four close pitches and it will hunt between them.
- Work outward from a reference course in the middle, not left to right. You want the notes you check octaves and fifths against to be nearby and already done.
- Check octaves by ear at the end, not by the dial. The dial gets each course onto its note; a beat-free octave across the instrument is what makes it sound like one instrument, and your ear is better at it than a needle.
- Go round again. Seventy-two strings pulling on one soundboard means the first courses have moved by the time you finish the last.
Frequently asked questions
How many strings does a santur have, and how long does tuning take?
A Persian santur has 72 strings in 18 courses of four — nine courses over the yellow bridges and nine over the white. Tuning all of it from scratch is an hour or more the first few times, and it is not a task you can hurry, because the four strings of a course have to be a beat-free unison before the course sounds like one note rather than a small chorus of itself. Day to day you are not doing all 72: you are checking the courses that have drifted and moving the two or three the next piece needs.
Why does tuning one course change a note somewhere else?
Because a course crosses its bridge and sounds on both sides of it. One string, one peg, one bridge in the middle — so tightening the peg raises the pitch on the left of the bridge and the pitch on the right of it at the same time, and the interval between the two stays fixed at whatever the bridge position makes it. That is the fact that governs a santur tuning session. You cannot correct one side without moving the other, and if the interval between the two sides is wrong the fix is the bridge, not the peg.
What notes should a santur be tuned to?
There is no single answer, and that is not a gap in this page. A santur’s pitch set is the dastgah: the instrument is tuned for the mode being played, and changing mode means physically retuning two or three courses, often by a quarter tone rather than a semitone. A chip bar of fixed targets would pick one kook and be wrong for every other piece in the recital, so this page gives you the chromatic dial and the structure instead. Set the concert pitch to wherever your instrument sits and work from the interval relationships.
One course sounds fine alone but rough in a chord.
Check the unison inside the course before you blame anything else. Four strings a few cents apart produce a beating that is easy to miss on a single struck note and very audible once the note is held under a chord. Damp three of the four with a fingertip or a felt wedge, read the fourth, then work across the course one string at a time. A santur that has every course centred on the dial and still sounds muddy almost always has courses that are internally out rather than collectively flat.
Can I use a chromatic tuner for the quarter tones?
Yes, using the cents readout rather than the note name. The dial names the nearest of twelve notes and tells you how far you are from it, so a quarter-tone degree reads as "the note below, about 40 to 50 cents sharp" — and that number is exactly what you are setting. What the dial cannot do is tell you what the number should be, because the size of a neutral interval is not fixed and varies by performer and school. Our tuning-systems page covers what actually varies and by how much.