A passive tube EQ that’s clean and precise enough for modern mastering
Passive tube EQs have long been praised for offering tremendous color and warmth. Their broad boosts and cuts and inherent saturation makes them a favorite option for overall tonal shaping. Knif Audio’s boutique Soma EQ updates the passive tube EQ approach by offering a cleaner, more flexible tone, as well as more precise EQ adjustments to meet the demands of contemporary mastering engineers.

The first passive tube EQ with “Real Q Adjustment” taking out the guesswork 
Despite their wonderful sound, old school passive EQs have their shortcomings as well. Changing the bandwidth control on a conventional passive EQ will cause you to inadvertently increase or reduce the amount of boost or cut you are applying, leading to unexpected changes in your EQ curve. The Soma EQ finally solves this problem by adding “Real Q Adjustment”. A first in the world of passive tube EQs, it allows for much more predictability and precision than any other EQ of its type.

Sophisticated and flexible color for discerning ears
While classic passive tube EQs like the Pultec and Massive Passive are celebrated for their warmth, saturation and character, there is such a thing as “too much of a good thing”. Sometimes the tone of these beautiful EQs can be excessive for a given track, forcing a mastering engineer to choose a totally different type of tool for the task. The Soma EQ offers a slightly cleaner and more subtle tone by default, with the option to drive it harder for additional warmth, making it one of the most adaptable processors of its kind.

Now with new features only possible in the digital domain
The plugin version of Knif’s Soma takes a high end analog EQ and updates it with extra features only possible in the digital domain. It is now easier than ever to increase or decrease the drive applied at the input and output stages to dial in just the right amount of analog goodness. The engineers at Brainworx have added indispensable tools for mastering, including a mono maker, stereo width control, and additional options for TMT.


  • An exacting model of the original Knif Audio design, made in close cooperation with boutique analog hardware designer, Jonte Knif.
  • Emulates the natural warmth of tubes and transformers, with fully variable saturation thanks to independent controls for headroom, input and output drive.
  • “Real Q Adjustment” makes Soma the most precise passive tube EQ on the market.
  • Stepped controls perfect for mastering applications.
  • Onboard Mid/Side processing.
  • Mono Maker, Stereo Width control and TMT on board.
  • Auto Listen feature to hear your EQ changes in isolation.
  • Selectable 6dB/oct & 12dB/oct slope high pass filters.
  • Employs Brainworx´ most advanced modeling yet to capture the complexity of this unique circuit design.
  • TMT — Brainworx patent-registered “Tolerance Modeling Technology” (US Patent No. 10,725,727)

Audio Examples

Industry Reviews

  • Simon Li

    Simon Li

    Faye Wong 王菲, Eason Chan 陳奕迅, Waa Wei 魏如萱, Lala Hsu 徐佳瑩

    I have my Knif Soma hardware EQ since 2014. It’s one of the best sounding mastering EQ out there. Congrats to Jonte and the Brainworx team to produce such a faithful recreation of the hardware… Read More

  • Zino Mikorey

    Zino Mikorey

    Mastering Engineer (Nils Frahm, Thom Yorke, Filous x The Kooks)

    I love this EQ, and I'm using it everywhere right now!

  • Eric Racy

    Eric Racy

    Mixing Engineer & Producer (Katy Perry, Pharrell, Lil Wayne)

    It's a tool unlike any other EQ I've used and the idea of a plugin version has had me more excited than any EQ emulation plugin in recent memory. You realize the genius of it a little more, each… Read More

  • Brian Vibberts

    Brian Vibberts

    Grammy Winning Mixing Engineer (Chick Corea, Sting, Metallica, Disney, Michael Jackson)

    The Knif Audio Soma EQ is easy to use and sounds fantastic on everything I tried it on - kick, snare, overheads, vocal, piano, mix bus! The sound of the EQ is smooth and I love the width options.… Read More

  • Brian Malouf

    Brian Malouf

    Producer and Mixer (Michael Jackson, Queen, Madonna, Pearl Jam, Stevie Wonder)

    Whether you’re using the unit as a rich, high quality software mastering EQ, or as a sweet sounding EQ while you’re still mixing, this unit gives you options and abilities not found in any… Read More

Customer Reviews

  • Tone for master

    by MiamiDude
    Great EQ for tonal shaping the master!
  • the best eq

    by dani diez
    I love using it for masterings, its color and warmth when it comes to giving a good sound is my hidden weapon

    by David Audio
    I Cant See Working without the precision and accuracy of this EQ.
  • Knif Soma in mastering

    by Mixthatrecord
    After mixing (and mastering efforts) for quite some time, I must say that this plugin is definitely most pleasing to my ears, period. I'm still not aware how passive tube characteristics are… Read More
  • SPL Mastering chain

    by Alfred
    First I thought, Oh, another EQ. Then I decided to spend my loyalty voucher on it and am I glad I did. I downloaded it and suddenly remembered I also had the SPL Iron and the SPL Vitalizer so I made… Read More


Supported Plugin Formats
AAX DSP, AAX Native, AU, AAX AudioSuite, VST2, VST3

Supported Operating Systems
macOS 14 down to macOS 11
Windows 11 down to Windows 10

Intel, or Apple Silicon

x64-compatible CPU

System Requirements
Display resolution: 1440 × 900px or 1280 × 960px or higher
Memory: 2 GB RAM


With the Installation Manager you can select, download & install all the Plugin Alliance products. Select any and all formats you need for your system! Mac & PC.



Knif Audio SOMA - Changelog

Version 1.1.1 (Oct 9, 2023)
- General: fixed CPU spikes on Mac OS

Version 1.1.0 (Aug 15, 2023)
- General: added native Apple Silicon compatibility for AAX
- General: added macOS Ventura support
- General: improved plugin loading time in the DAW
- General: fixed issue causing Logic to crash when closing the plugin UI
- General: improved font drawing behavior

Version 1.0 (25 Jan, 2022)
- Initial version