Abstract: A vibration controller has a vibratory mechanism with a pulley assembly with four pulleys coupled in pairs on two shafts linked by two belts. The pulley assembly is mounted under a reception table or tables for products to be vibrated and compacted. The pulleys receive offcenter weights for forming an unbalance. The weights are placed only on a aliametric portion of the pulleys. The pulleys are mounted in pairs on the two shafts associated with an phase-shifting device that rotates certain pulleys with respect to each other to vary the relative orientation of the corresponding weights. According to this orientation one can obtain maximum, partial or minimum vibration, one of the shafts being driven by a motor unit.