23. Band-pass Filters
The band-pass filter is yet another filter used in some synthesizers. The band-pass filter, as the name indicates, allows a specified band of frequencies to pass while it attenuates those above and below that band. In this type of filter a bandwidth must be specified. The bandwidth is simply the arithmetic difference between the highest and lowest frequencies that are permitted to pass unattenuated. The user might determine that frequencies between 600 and 1000 Hz shall be allowed to pass, while any other frequencies will be attenuated.
Example 23-1: A band-pass filter attenuates frequencies outside the specified band of frequencies.