Various approaches have been used to automated the on-line control of pressure drop in filter rod making. "Over control" has often been the result because of the inertness of mechanical drives used in traditional blooming units. A new approach uses the pressure on the non-driven pretension rollers in common two-stage blooming units to alter and adjust the amount of filter tow entering the filter rod machine. The system can be applied to traditional filter rod makers and is also suitable for the next generation of double-rod equipment.