Anton Karas improved the design of the concert zither, which replaced the Volkszither, which had four melody strings and less than fifteen accompaniment strings.
In 1838, Nikolaus Weigel of Munich conceived the idea of adopting fixed bridges, adding additional strings, tuning them in the cycle of fifths, and chromatically fretting the fingerboard  effectively converting a rather crude folk instrument into the concert zither. His ideas were not, however, widely accepted until 1862, when luthier Max Amberger of Munich fabricated a new zither based on Weigel's design. At this point the zither had reached something very close to its modern concert form. Within a relatively short time the new design had largely replaced the old Volkszither (though still called by the same name among folk musicians) throughout central Europe, particularly in the Alpine countries. 
