• Inputs: Balanced XLR & 1/4” (accepts unbalanced)
• Outputs: Balanced XLR (accepts unbalanced) & Unbalanced 1/4”
• Level +4 dBu nominal
• Bypass Switch bypasses EQ & tube circuits: 1/4” Jacks (not hardwire)
• Bypass Switch bypasses EQ, tube circuits & Input Buffer: XLR Jacks (Hardwire Bypass)
• Gain Trim: -6dB - 0dB - +4dB
• 44 Frequencies (roughly 1/4 octave spacing)
• Frequency Range: 22 Hz to 27 kHz
• EQ Boost/Cut Range : Maximum 20 dB boost or cut
• Nominal Q range: 1.5 to 3 (uniquely active in shelf modes)
• Maximum Input Level: +21dBu
• Maximum Output Level (1kHz sine, 1% THD+N, BW 22Hz-22kHz, Load 100kOhms): +35dBu
• Frequency Response (@ +4dBu, Load 100kOhms): -0.1 dB @ 10Hz, -1 dB @ 60 kHz
• Total Harmonic Distortion (THD+N) (1kHz sine @ +4dBu, BW 22Hz-22kHz): 0.006%
• Output Headroom (Reference to +4dBu): 31dB
• Dynamic Range (Reference to Maximum Output): 123 dB
• Noise Floor Typical (Unity Gain): -88 dBu (A-Weighted)
• Signal to Noise Ratio (Reference to +4 dBu, BW 22Hz-22kHz): 92dB
• Input Impedance: 20kOhm
• Output Impedance: 150 Ohm
• Tube Complement: 2 x 5751, 4 x 6922
• Auto-mute warmup delay = 20 seconds
• Power Consumption (120/240VAC): 44 watts
• Mains Voltage & Frequency (VAC/Hz): Internal Universal Power Supply 90-254 VAC / 50-60Hz
• Size (3U): L 19” x W 10” x H 5.25”
• Unit Weight: 15.5 Lbs.
• Shipping Box: L 23” x W 15” x H 10”
• Shipping Weight: 26 Lbs.

• 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 plus gain trims
• Units built after 2016 or 2017 MK2 revision have Hardwire Bypass.

The Massive Passive is a truly unique equalizer — it’s passive, parallel, and built with Manley’s signature musicality.
Its filter network is entirely passive, using only resistors, capacitors, and hand-wound inductors — no op-amps or active circuitry in the EQ path. A clean tube amplifier stage restores the signal level afterward, giving you the open, effortless tone that’s become a Massive Passive hallmark.

Unlike most EQs with series filter topology, the Massive Passive runs its four bands in parallel. This means you can apply broad or extreme boosts without internal overload — even with multiple bands overlapping.

Every band can operate as a bell or shelf, and the curves interact organically rather than clinically. The result is a rich, musical sound that enhances tone instead of dissecting it — often described as “Pultec on steroids.”

The Massive Passive has the smoothest yet punchiest mid bands in the industry, and don't take our word for it. The lack of phasy midrange, even when pushed a bit, makes it an ideal EQ to use in M/S mode. While it works great with any M/S matrix out there, the combination of the Massive Passive and our Backbone Insert Matrix is a team that needs to be heard and experienced!

The Massive Passive is designed to serve across the entire production chain:

• Tracking: Add tone shaping and musical enhancement while recording, with natural warmth and depth from the tubes and passive network.

• Mixing: Sculpt instruments or entire buses with broad, organic curves that add space and cohesion without harshness.

• Mastering: The Massive Passive Mastering version offers stepped controls for precise recall. It’s ideal for subtle tonal balancing, gentle enhancement, and removing unwanted buildup — all with immense headroom and minimal phase distortion.

In short, the Massive Passive is equally at home on vocals, acoustic instruments, mix buses, or entire masters.

In the Massive Passive, Bandwidth replaces the conventional Q control.
It defines how wide or narrow the EQ curve is, but with a twist: the filters are interactive.

• Turning Bandwidth counterclockwise creates broader, smoother curves.

• Turning it clockwise tightens the curve for more focused adjustments.

• In shelf mode, the Bandwidth control also changes the shelf shape — introducing a gentle dip or bump near the corner frequency for more musical contouring.

Unlike a fixed, clinical Q, the Massive Passive’s Bandwidth works dynamically, influencing the tone and interaction of neighboring bands. This makes it more musical than mathematical — you’ll hear results that feel natural, not surgical.

If your Massive Passive is a newer production unit, it likely includes our modern MANLEY POWER® switch-mode power supply (SMPS). You can identify it easily:

• A red illuminated push-button replaces the older black rotary power switch.

• Universal power input: no voltage selector needed (automatically handles 90–254 VAC, 50/60 Hz).

• Updated internal design: revised tube complement, PCB layout, and power section.

If your unit has these features, it’s equipped with MANLEY POWER®. Earlier models used a traditional linear supply.

No.
Due to major changes in the power, audio, and mechanical design, it’s not possible to retrofit older units with the MANLEY POWER® SMPS system. The newer chassis, wiring, and PCBs were re-engineered from the ground up.
Manley therefore does not offer a conversion service — we recommend continuing to enjoy your classic version or upgrading to a current production unit.

Tube complements vary slightly depending on the production era.

• Current MANLEY POWER® version:
  2 × 5751 tubes (gain stages)
  4 × 6922 / ECC88 tubes (output and driver stages)

• Earlier linear versions:
  2 × 5751 or 12AX7 tubes
  4 × 6414, 12BH7, or 12AT7 tubes depending on revision

Always use the correct retube kit for your serial number — older and newer versions are not interchangeable.
For replacements, Manley offers matched and tested tube kits via our official service partners.