A type of filter. A band-pass filter only allows through a selected band of frequencies in the middle of the frequency range. It is not used very much....
OB-X
"Oberheim released the polyphonic and programmable OB-X in 1979. Available in four-,
six-, and eight-voice configurations, it offered 32 program memories, polyphonic
portamento, and polyphonic sample-and-hold."