The NL125/6 band-pass filter module employs two active sections to control the high and low pass characteristics. The low frequency cutoff point can be set continuously from 0.5Hz to 5kHz with a single turn potentiometer, in four switched ranges. Similarly the high frequency cutoff can be set continuously from 5Hz to 50kHz in four switched ranges. DC and WB (wide band) switch positions by-pass the lower and upper filter sections, respectively. A switcheable active notch filter is provided for the rejection of line frequency interference; this can be set by the user to 50Hz or 60Hz, with a 20Hz notch width (-3dB points).