Conventional MC cartridges utilize a steel suspension system (tie wire) which creates a high amplitude H.F resonance (normally around 8-12Khz). Such resonance is unacceptable and is usually damped by a rudimentary piece of foam rubber.
However, the foam rubber deteriorates with age and cannot prevent the complete structure from vibrating and "ringing".
The specifics and adjustment of the tie wire and damping determine whether the cartridge is under damped (bright) or over damped (warm and bass heavy).
A happy medium is rarely achieved.
This encouraged Rega to pursue a new direction inspired by modern materials and the basic laws of magnetism. The Rega Apheta contains neither a tie wire nor a foam damper. After 4 years and many hundreds of experiments, the innovative design of the Apheta was complete.
Moving coil aficionados will all recognise the long search for super clear high frequency combined with firm, tight bass.