The Manley Massive Passive is a four-band, dual-channel, valve passive EQ designed to provide an organic and extremely musical sound even with high settings. It also features stepped gain controls.

The Manley Massive Passive uses passive components for its equalisation and exploits their natural qualities avoiding the distortion inherent to active circuitry. As a result, the Massive Passive can provide twice the amount of EQ with half the colouration of most designs for a truly natural tone.  Incorporating the strengths of Pultec designs, as well as some choice console EQs parametric and graphics, the Massive Passive is nonetheless a truly different EQ. From subtle enhancements to radical sound-shaping this audio equalizer does it all. For example heavy HF boosts will add a lot of presence to vocals without adding sibilance, and LF will add heft without mud.

Unlike most EQ designs, All four bands of the Massive Passive are not built-in series but in parallel. This means that overlapping frequencies do not suffer from the cumulative effect of tweaking each band. As each band works from the exact same source, the result is much more transparent.  Each band can be set to bypass, boost or cut as well as a bell or shelf.  Each band is capable of 20dB of boost or cut with impressive headroom. Five extremely steep high-pass and low pass filters are also added to remove unwanted frequencies such as low-end rumble. Both HPF and LPF interact with the main parametric EQ section.