A data reader arranged to produce a signal on reading a data holding medium (4), said data reader comprising processing circuitry (8) arranged to process said signal, said processing circuitry including a filter (14) having a variable cut-off frequency (FC), a velocity signal generator (23) arranged to produce a signal (21) corresponding to the velocity of the data holding medium (4), and a processor (22), said processor (22) being arranged to read the velocity signal (21) and set the cut-off frequency (FC) of the filter (14) The data reader is generally arranged to be incorporated into a tape drive (2) arranged to be used as a computer data storage device.