An adjustable resonator stop may be used in resonators of keyboard percussion instruments. The adjustable resonator stop includes a resonator engaging body having a cavity, a resonator end member being configured to be disposed within the cavity of the resonator engaging body, and a tightening member coupled to at least a portion of the resonator end member. The tightening member is configured to move the resonator end member from a disengaged position, wherein the resonator stop may be freely adjusted within a resonator, to an engaged position, wherein the resonator stop may be securely coupled to an interior surface of the resonator. The adjustable resonator stop may provide the same or better performance characteristics as a permanently installed metal stop including a smooth, metallic, bi-polar vibrating surface with exposure to air on either side, while also providing quick adjustability at little or no cost when compared to other adjustable stops in the industry.