A tension adjustment hoop (1) for tensioning a resonant
skin (13) on a
musical instrument (6, 25), the tension adjustment hoop (1) being formed by a ring (2) with a center axis (3) and with retention means (4) arranged to interact with
coupling means (5) on the
musical instrument (6, 25) for retention of the tension adjustment hoop (1), the tension adjustment hoop (1) having an opposing top side (7) and bottom side (8), where the tension adjustment hoop (1) comprises an inner fluid channel (17), provided with a pressure adjustment connection (26) in
hydraulic connection with the fluid channel (17), and a plurality of pistons (10), each in
hydraulic connection with the fluid channel (17), each with a free end (11) opposite the fluid channel (17), and each, under the influence of the pressure in the fluid channel (17), being displaceable in a direction parallel to the center axis (3) of the tension adjustment hoop (1) between a first
extreme position, where the free end (11) is within or level with the bottom side (8), and a second
extreme position, where the free end (11) is outside the bottom side (8).