A data reader derives a signal on reading a data holding medium. The data reader has processing circuitry to process the signal. The processing circuitry includes a filter having a variable cut-off frequency, a velocity signal generator that produces a signal corresponding to the velocity of the data holding medium, and a processor. The reads the velocity signal and sets the filter cut-off frequency. Calibration data derived during a calibration operation of only the particular data reader determines the filter cut-off frequency for different speeds of the medium during normal read operations of the medium.