The main components of a rotational rheometer are the motor with its supporting bearings systems and the force measurement. In one design, commonly referred as CR (controlled rate or controlled strain) or SMT (separate motor transducer), a displacement or speed is applied to the sample by a motor and the resulting torque is measured separately by the use of an additional measuring sensor. In a so-called CS (controlled stress) rheometer or CMT (combined motor transducer) design, an electrical current is applied and builds up a magnetic field, which produces an electrical torque. In such a design there is no separate torque sensor needed, since the torque signal is calculated from the motor current. The movement of the motor shaft is measured by an angular displacement sensor. In 1995 a CS (or CMT) rheometer equipped with an electronically commutated synchronous Motor (EC-Motor) and Digital Signal Processor (DSP) technology was introduced. The EC-motor technology is now for 17 years in various generations of instruments commercially available, making the technology with thousands of installations well established. Since its first introduction significant improvements, due to the use of enhanced electronics, improved materials, and more sophisticated control mechanisms, have been implemented. Now a completely new rheometer concept based on two air bearing supported EC-motors is introduced, which represents a large step in rheometer development and extends the capabilities of a rotational rheometer dramatically. The combination of two motors into one rheometer system offers increased sensitivity and many new testing capabilities not possible before. Three completely different testing modes such as combined motor transducer, separate motor transducer and counter rotation are available in one single rheometer system. The aim of the paper is to describe the new technologies involved and to present examples relevant for modern research on various rheological topics.