Reference Sound Source uses a specially designed centrifugal fan driven by a powerful asynchronous motor. The motor is of the external rotor type, and due to the high moment of inertia of the rotor it has a very constant speed of rotation. The motor is mounted on a cast aluminium base, shaped to minimize reflections. The complete assembly of motor and fan is mounted in a cylindrical safety grid fitted with two carrying handles.
Additional features of the compact and rugged product include long-term stability, an individual calibration chart and a safety grid.