adjusting action in Jam Session - General Discussion Posted January 15 Alongside -- we actually set a dime on the fretboard next to the 1st fret. The coin is marginally taller than the fret. Probably best not to use anything relating to guitars/mandolins/banjos when 'messing about' with dulcimers. The construction techniques are different. The dulcimer does not produce the majority of its sound by vibrating the top. Dulcimers don't want a complex system of braces under the top or bottom, they don't need kerf strips glued into the edges of the sides, etc.