517 Coupled LP/HP Filter

LP + HP = BP

This module combines two VOLTAGE CONTROLLED FILTER circuits in one triple-width unit.
The two identical filters are switchable high pass/low pass filters with independent controls for cutoff frequency and regeneration.
The four-mode combinator allows using the filters as – two separate filters (”stereo mode“) – two filters in series (”maximum slope“) – notch/band reject mode – band pass mode.
The balance between filter 1 and 2 and the bandwidth are voltage controllable.
An additional jack combines both filters' audio outputs.

http://www.lunar-experience.com/download/517.pdf