The king of parametric EQs
The PQ Mastering Equalizer is a fully parametric, dual-channel five-band equalizer, based on SPL’s pioneering 120V rail technology. Able to switch between constant and proportional Q modes with the push of a button, this kind of circuit has not yet been achieved in any other analog equalizer.

Designed for precision performance
Each of the five bands of the PQ can be independently activated, deactivated, or switched between Constant Q and Proportional Q modes for even more targeted cuts and boosts. Thanks to the “1/4 Gain Switch”, you can reduce the range of the EQ from +/-20 dB down to +/-5 dB cut or boost to easily perform the small corrections common in mastering. And, with the detented potentiometers, precise settings are easy to dial in.

Now improved with plugin-only features
Brainworx’ familiar “Extra Unit” adds features to this legendary EQ that cannot be found on the original analog units. This retractable module includes Tolerance Modeling Technology, M/S Processing, Mono-Maker, Stereo Width, THD, Auto Listen for all five bands and more, providing everything you need in the modern digital domain.


  • Exacting emulation of the original analog PQ mastering equalizer, approved by SPL
  • Fully parametric mastering grade EQ, that offers precision, flexibility and detailed musicality
  • Independently switch between Constant Q and Proportional Q for all 5 bands for more targeted boosts and cuts
  • BRAINWORX Plugin Only Features added to the BX Module
  • Brainworx ́ TMT inside: Tolerance Modeling Technology (TMT, US Patent No. 10,725,727) simulates channel-to- channel variances in electronic components for the most realistic analog sound in the box
  • Auto Listen - To more accurately position the filter in the frequency domain by isolating the effect of the EQ
  • Mono-Maker - Sums your low-frequency content to mono, giving you focused, punchy bass response
  • Stereo Width - To expand the stereo width of your tracks
  • Separate Mono Version - for using individual tracks such Kick Drum, Snare, Bass, Vocals, etc.
  • Scalable User Interface
  • Artist Presets

Audio Examples

Industry Reviews

  • Howie Weinberg

    Howie Weinberg

    15 Grammy Awards, 32 Grammy nominations

    As an owner of the original hardware SPL PQ, Plugin Alliance made a unit that truly mirrors the original sound - warm and really analog sounding.

  • Joost van den Broek

    Joost van den Broek

    Producer, Arranger & Mixer (Blind Guardian, Powerwolf, Ayreon)

    This plugin really adds the ultimate parametric EQ to your in-the-box toolkit. Amazing to have this famous master EQ as a plugin now!

  • Eric Racy

    Eric Racy

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

    Like most people, I have countless EQ plugins. Generally, EQ plugins are either surgical tools that allow you to fix issues or they are good at “sweetening” and broad stroke enhancement. The… Read More

  • Conan Manchester

    Conan Manchester

    DJ, Producer, Engineer & Remixer

    Since going 100% in the box, the PQ has been the last on my wishlist for mastering EQs. PA has nailed this and the fact I can open multiple instances means I can think broader than just… Read More

  • Lucas (Luke) Pimentel

    Lucas (Luke) Pimentel

    Multi-Gold & Platinum Mastering Engineer (Jeremy Riddle, Marcos Witt)

    The PQ is a fantastic unit and this emulation will be a perfect complement for the PassEQ.

Customer Reviews

  • Great mastering EQ

    by Alfred
    A wonderful masterin EQ with a lot of possibilities. I made an all mastering chain with SPL components and it works like a charm! The masters are very good sounding and glued together in combination… Read More
  • Shaping a sound

    by Massivebeatzz on Youtube
    What a delight to use, and work with. The mix decisions I make on this, and the way it preserves the sound is very close to analog hardware The scable UI to 150% makes this bigger on my 46" Monitor… Read More
  • polished elegant EQ

    by langelo68
    Beautiful polished, airy, elegant sound with pristine quality yet not clinical. Best mastering EQ I have ever used. subtle yet deep. tons of headroom gives your mixes that final polished professional… Read More
  • SPL PQ

    by PMT Studio
    Great mastering eq has retained some of the flavours of the analog gear as well as more functionality from the BX team.
  • The Best...

    by Goldenchild / WM
    The SPL-PQ is special. It is by far the best Mastering EQ I've use in the Box. This EQ & the AMEK 9099 is really all you need, they compliment each other well. Great job Plugin Alliance on this one.


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

Supported Operating Systems
macOS 12 down to macOS 10.11
Windows 11 down to Windows 8

Intel, or Apple Silicon (except for AAX) architecture

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.



SPL PQ - Changelog

Version 1.1 (Feb 01, 2023)
- General: codebase refactored
- General: Fixed that the signal on the right channel is lower then left when Auto-Bypass is turned on in Mid/Side mode.
- Added feature to set default UI color

Version 1.0 (Sep 22, 2022)
- Initial Release