The present study aims at the design of the active control of machine tools' vibrations. The formulation of modal control for linear lumped parameter vibratory systems is offered. The electromagnetic exciters are developed to serve as active dampers for machine structures. A simple L-shaped beam structure is the object for the experiments and is mounted with two electromagnetic exciters. The behavior of the whole system is investigated by the model that is composed of the lumped masses and springs with 4-degree of freedom. The control system is designed through the investigation both by the root locus method and by the "MATLAB Simulink" simulation in which the elapsing responses, C ₁(t),…, C ₄(t) of all four modes and the vibratory waveforms, W ₁(t),…, W ₄(t) are computed. The best condition for the values of control parameters results by the simulation. In the experiment, the preparatory study for the vibration control of the L-shaped structure has been performed in advance to the investigation.