Bandpass filters pass the selected range or band of frequencies (without distorting the input signal) that can be either narrow or wide, attenuating all those outside of this range. In other words, a frequency selective filter known as Band Pass Filter (BPF).
The bandwidth of the filter is the difference between the upper and lower cutoff frequency points of two filters.
BNDP556 bandpass filter is a pair of frequency cutoff state-variable filters, designed to adjust the audio frequency bandwidth.
The filters are 3-Slope (18 dB/oct), designed for Butterworth response.
The cutoff frequencies are tunable. The Low-end cutoff filter can be adjusted to a frequency in the range from 20 Hz to 200 Hz. The High-end cutoff filter can be adjusted to a frequency in the range from 2 kHz to 20 kHz.
The ideal bandpass filter would have a completely flat response (all frequencies would be passed to the output without amplification or attenuation, and would completely attenuate all frequencies outside the passband). In practice, bandpass filters are not ideal. There is a region outside of the intended passband where frequencies are attenuated, but not rejected. This is a filter roll-off (stop-band) before and after the bandpass range.
A bandpass filter can be characterized by the flatness of the frequency response Bandpass filters can be used as tone shaping elements.
BNDP556 is inspired by the legendary UREI™ 556 Variable Bandpass Filter.

Try out BNDP556 variable bandpass filter in the Reason Rack

LOW CUT: Low-end (Highpass) State-Variable Filter, that cuts the Low frequency from 20 Hz to 200 Hz

HIGH CUT: High-end (Lowpass) State-Variable Filter, that cuts the High frequency from 2 kHz to 20 kHz

LOW FREQ FLATNESS: Sets the flattest possible frequency response of the LowCut filter

HIGH FREQ FLATNESS: Sets the flattest possible frequency response of the HighCut filter

OUTPUT: Sets level of the processed signal

ACTIVE FX: Switches the effect between Active and Soft-Bypass modes. Variation of effect bypass with fade in and fade out that excludes loud peaks when you enable or disable the effect