Abstract: A portable, hand-held concrete vibrating system employs a pendulous vibrator driven by a high speed, two-cycle motor that operates up to speeds of between 5000 and 6000 RPM. An elongated, rod-like frame supporting the motor is connected at its remote end to a vibrator head adapted to be immersed in plastic concrete. A pivoted weight generally coaxially disposed within the head forcibly causes vibrations in response to internal impacts. A compensating system within the head torsionally couples the flexible drive cable to the pendulous weight and accommodates axial and rotational stresses caused by high speed rotation. The compensating system, preferably disposed between sets of self aligning bearings, comprises a rigid power input end coupled to a rigid power output end by a resilient, preferably buna rubber midsection.