String tensioning system for a stringed instrument having an instrument body, at least one tensionable string that is fixed at both its ends to the instrument body, and a chamber accommodating a portion of the at least one tensionable string when the portion is arranged between a string introduction aperture and a fixing point arranged opposite to the string introduction aperture, wherein the system includes at least one string tensioning device that can be activated from outside of the instrument body. The at least one string tensioning device is accommodated in a chamber of the instrument body. The at least one string tensioning device includes a tensioning screw and a string tensioning head. The tensioning screw extends into the chamber. The string tensioning head is connected to the portion and is movable in a longitudinal direction by rotating the tensioning screw. A free space is arranged on opposite sides of the string tension head. Each free space allows for a free movement of the portion between the string tensioning head and the feed aperture and between the string tensioning head and the fixing point. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.