my EMT R 80 runs without feltbrake. To adjust speed and also to filter the voltage I am using the DU 937. All other 927 models do have a feltbrake with a manual switch on the left side (green lamp). It reduces the a little too high speed in a small range to end up with the normal speed (e.g. 33.33) or a little lower if you like. Nevertheless you have a pretty silent noise and you need to renew the inner felt ring and the brake panel sheet after some 5 to 10 years.