 Because many of the DP70s remaining in use today are in repertory venues that screen a wide range of formats, including prints of silent movies that require a lower frame rate than 24, very many have now received aftermarket modifications that will typically enable any speed between 16 and 30.Since US market DP70 seem to be factory equipped with synchronous motors that lock their speed (1,800 RPM in the USA) to the AC line frequency (60 Hz in the USA), the most common way of doing this has been to add a variable frequency solid state AC inverter (Baldor Inverter) to drive the 24fps motor.Most European units were sold employing asynchronous motors, which added slip to the synchronous speed (1500 RPM at 50 Hz) to achieve the required 24 frames (1440 RPM) and 30 frames (1800 rpm), without gearing requirements in the original construction.