Raul,
"Dear fleib: why is the best team those cartridges with that 66?, maybe I'm missing something and always is time to learn so some " light " from you can help all of us."
Sorry, I didn't see your post. Those carts are very low compliance. A low compliance cart needs high effective mass arm to control the cart and be a stable platform. Put a stiff, heavy tracking cart on a low mass arm and the resonant frequency approaches or goes into the audio band. The amplitude of the resonance can be quite high, producing colorations.
On another forum someone mentioned that a "guru" advocated a resonant frequency of 18Hz for a particular cart. I can only assume this was to augment the deep bass on his records or system.
We often deal with the opposite situation - a cart with compliance too high for a particular arm. In that case the resonant frequency goes low - easier to live with if SQ doesn't suffer from poor low frequency tracking and/or sluggish sound. Peter Pritchard (designer of 50cu carts), advocated a resonant frequency of 6.5Hz. This is above the warp region yet the arm will have enough mass to be stable. Arm damping (fluid) acts to limit the amplitude of the resonance peak and spread it across a wider frequency band, mitigating the affects.
Regards,