The Persian Santur is the original form of the hammered dulcimer. The Hammered dulcimer is ancestor of the Piano. The original Santur is a diatonic instrument. Santur is a three-octave wooden trapezoid-shape instrument with Seventy-two strings which are arranged in eighteen quadruple sets, nine (bronze) in the low register, and nine (steel) in the middle register. The 72 strings, assorted in groups of four, i.e. each of four closely spaced strings are tuned to the same pitch. Each group of four strings is upheld by a tiny, movable, wooden bridge; the bridges are positioned to give the instrument a range of three octaves. The four strings over a bridge are tuned to the same pitch. The bass strings are usually made from bronze whereas the strings over the middle bridge are steel.
The resonance box of the traditional instrument is usually made of hard wood, for instance walnut. There are several sound posts inside the box, which connect the table of the instrument to its back. The arrangement of the sound posts plays important role in the sound quality of the instrument. There are two small rosettes on the top panel, which help to amplify the sound.