Friction damping is one of the main mechanisms for dissipating vibration energy in turbomachinery. For assembled bladed disks, friction typically arises in the blade root — in the disk interface or, for shrouded blade configurations, in the interface between two consecutive shrouds. For integrally bladed disks, where no such interface naturally occurs, additional damping devices must be designed if energy is to be dissipated through friction. Split-ring dampers are such devices: they are located in a circumferential groove under the blisk platform, and pressed onto it by centrifugal loads. At low vibration levels and/or high rotating speeds, the split ring remains stuck to the disk, while at high levels, relative motion starts and dissipates vibrational energy. Such devices are often designed to mainly target a given nodal diameter mode of vibration. Nevertheless, designing these dampers is a challenging task. Indeed, their behavior depends on the design of the ring (dimensions, material and interface properties, etc.) and on the location of implementation; many different phenomena are involved such as centrifugal and thermal loading, mistuning, etc. Realistic contact modeling and simulation are also difficult because the dynamical behavior is non-linear due to the friction interfaces. In this work, the effect of a split ring damper is investigated experimentally on an industrial compressor blisk in a vacuum chamber. A traveling wave excitation with a prescribed nodal diameter index is produced using piezoelectric actuators. Blade vibrations are monitored through strain gauges. Forced responses are measured, first on a tuned configuration activating the split ring damping effect on the targeted specific nodal diameter. Then an intentional mistuning pattern is implemented, so that the split ring target nodal diameter appears in different modes of the new configuration. The experiments show that resonance peaks are damped for different modes from that targeted at the tuned design stage.