An ultrasonic transducer driving circuit configured to supply an output current andor an output voltage to an output line for driving an ultrasonic transducer is provided. The preform is pressed with a mold until at least one wall portion is bent toward a gap within the mold, and a plate thickness is increased at the at least one wall portion and the connecting wall portion by pressing other wall portions. The ferrule is mounted within a housing which includes a forwardly facing abutment surface for engaging the rearwardly facing abutment surface on the ferrule. Preferred corrugated media having fold arrangements, filter constructions having such fold arrangements, and filter system using such filter constructions are provided.