Manley Labs Massive Passive Stereo Tube EQ Mastering Version

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  • Stepped Knobs Ensure Repeatability
  • Passive Inductor-Based EQ
  • 4 Bands of Parametric EQ per Channel
  • Switchable Shelf EQ with Bandwidth Shape
  • Hand-Selected Vacuum Tubes
  • Hand-Wound Output Transformers
  • Parallel Symmetrical Topology
  • Auto Warm-Up Delay: 20 Seconds
  • Bright Blue LEDs for Active Functions
  • 3U Rackmount


he Massive Passive from Manley Labs offers two channels of 4-band parametric equalization with additional 5-band high pass and low pass filters. Its design draws from vintage EQs using passive, parallel topology to create a natural and organic tone. Simple circuits with premium-quality components, like metal film resistors, film capacitors, and hand-wound inductors are used for sculpting the sound. The mastering version uses mechanically detented bandwidth, gain, and gain trim knobs to ensure repeatability, but limits the range of operation. The high pass and low pass filter slopes have been tuned specifically for mastering settings.

Each of the 4 bands offer Pultec-style controls, each with fixed frequency selections, variable bandwidth and either 11 dB of boost or cut. This design allows for twice the control resolution over conventional mastering EQs and eliminates the problem of a center detent not guaranteeing a flat response. The parallel topology allows for massive tone shaping without over driving the outputs. For instance, if you were to boost 4 bands at 1 kHz by +11 dB, the output would still only be +11 dB, whereas a conventional “series” EQ, would output upwards of +44 dB.

Additional features include individual band bypass and the ability to switch each band from bell curve to shelf. The two left-most bands offer low shelf capabilities, while the right two offer high shelf. The bandwidth knob changes the properties for each of the shelves as well. The unusual “Constant Bandwidth” controls offer unique tone shaping capabilities. In bell mode, they behave like most “Q” controls of a parametric EQ with a wider shape when set fully counterclockwise and narrower when set fully clockwise.

The shelf modes offer a special function. When the knob is set fully counterclockwise, the curves are similar to most shelf EQs. As you increase the bandwidth clockwise, a gradual bell-shaped dip is introduced as the slope increases, which modifies the overall shelf shape. It’s rare to find an analog EQ with adjustable high shelf curves.

The high and low pass filters are individual circuits selected by switch settings, and each filter slope is set at 18 dB/Octave, with the exception of the highest 52 kHz low pass filter offering a 30 dB/Octave slope. All the filters are entirely passive and “inserted” between the boost and cut sections. The two “EQ In” push buttons engage the EQ on their respective channels. When bypassed, the EQ section and tubes are bypassed, but audio signals are still passed through the line amplifier and balanced output transformer. The -2.5 to +2.5 dB gain trims are true 11-position, 1/2 dB stepped Greyhill switches intended to help level match between the “Bypass” and “EQ In”.

There are no dedicated meters on the Massive Passive, instead bright blue LEDs indicate “EQ In,” while red and green LEDs indicate cut and boost engagement respectively. Hand-made in the USA, the unit is housed in a 3U steel chassis with a CNC-machined 1/4″ faceplate that is also inlaid with laser-engraved inserts. The Massive Passive ships with an IEC power cable.


  • Mechanically detented switches ensure repeatability
  • 44 selectable frequency bands
  • All-passive tone sculpting circuitry
  • Unique shelf curves use the “bandwidth” control
  • Overlapping and interleaved frequency choices
  • Every band switchable to shelf or bell
  • Vacuum tube make-up gain and line drivers
  • Parallel symmetrical topology
  • Premium components throughout
  • Passive HP and LP filters tuned for mastering
  • Gain trim for level matching
  • Auto-mute warm up delay offers 20 second buffer before passing signal

Center Section for Each Channel

  • EQ In: Bypass for EQ, filter and tube section. Line amp and output transformer are still active in bypass
  • Gain Trim (-2.5 to +2.5 dB): For level matching between “EQ In” and “Bypass” modes
  • Low Pass Filter (6-Way Switch): Selects off or 1 of 5 available filters
  • High Pass Filter (6-Way Switch): Selects off or 1 of 5 available filters

4-Band EQ Per Channel with Each Band Featuring

  • 2-Way Toggle Switch (Bell/Shelf): Switches EQ mode
  • 3-Way Toggle Switch (Boost/Out/Cut): Switches boost or cut mode. Out is the band bypass
  • Gain Knob (0 to 11 dB): Sets cut or boost depth
  • Bandwidth Knob: Adjusts the width of the bell curve or shelf shape
  • Frequency Switch (11-Position): Selects a fixed frequency


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