Abstract: The inventive apparatus has two plastic supports (2) mounted, in registrer with the top and bottom sides of the yoke body (1), and crown (1a), in which they are structurally incorporated. Preferably, the plastic supports are rectangular with rounded edges. Each support has hooks (3) to receive the compensation coils which are snap-fitted thereon. Also, each support has pins (5) for fastening the coil terminals 4a, 4b. The pins also support a damping cell when required. The cell includes a registor (6) connected in series with a capacitor (7). The compensation coils (4) can have a variable number of turns, depending upon the compensation which it is to achieve.