4K EQ 2
Calibrated British Console EQ with Brown and Black Voicings
Available Now
4K EQ 2 is a ground-up rebuild of 4K EQ, modeling the equalizer and high-pass/low-pass filters of a classic British E-series channel strip band by band. Completely free.
Overview
Brown and Black are separate voicings rather than cosmetic themes. Each was measured independently: its own frequency, gain, Q, shelf, filter, interaction, nonlinearity, and overload behavior. Use it for broad tonal decisions where a console EQ is faster than a surgical parametric equalizer: shaping drums, moving a vocal forward, removing low-end clutter, or adding a restrained shelf to a mix bus. The LMF and HMF sections stay fully adjustable when a narrower correction is needed.
The modeled EQ path carries a fixed amount of native nonlinear color, the same as the reference channel strip. There is no separate Drive control; raise Input to push the modeled path harder, then trim Output to compare fairly.
Open Source
4K EQ 2 is open source under GPL-2.0. View the source, report issues, or contribute on GitHub.
Disclaimer: This is an independent emulation inspired by classic British console EQs. This project is not affiliated with or endorsed by any hardware manufacturer.
Features
- Two calibrated voicings: Brown (E-series) and Black (G-series), each independently measured
- 4-band EQ (LF / LMF / HMF / HF) with switchable Bell/Shelf on LF and HF
- Adjustable Q on the LMF and HMF bands
- High-pass and low-pass filters
- 1x / 2x / 4x oversampling for cramp-free high-frequency response
- Fixed modeled path nonlinearity driven by Input Gain, matching the reference channel strip
- Auto Gain compensation toggle
- Real-time pre/post FFT spectrum analyzer overlaid on the response graph
- 14 factory presets plus a user preset library
- Resizable interface
- Full automation support
Changelog
v1.0.5 2026-09-06
- Frequency knobs regain their full travel
- Shared printed knob ring and detent laws
- Framework update (DAF 22b82824, pugl d46e7871): the first click on an unfocused editor registers on macOS, macOS resize sizing fix, drawing state set up on the expose path, AU buffer handling fix, Wayland backend updated
v1.0.4 2026-08-29
- Fixed the GRAPH toggle leaving the editor clipped on the right, or with empty space below it, in hosts that keep the window on a fixed aspect ratio (CLAP and VST3)
- Fixed the window aspect the plugin reports to the host, which was very slightly wrong and made hosts size the editor a pixel off its design
- Fixed knob dragging stopping when the plugin window loses keyboard focus mid-drag
v1.0.3 2026-08-28
- Fixed VST3 output peak meters being reported to the host as parameter edits, which churned the undo history in hosts such as Bitwig until Undo and Redo were no longer offered, and marked the project modified on every save (#233)
- Added VST3 and CLAP regression harnesses, plus an editor drag test, that fail the build if output parameters reach the host or if a knob stops responding to the mouse
v1.0.1 2026-08-26
- Fixed CLAP output peak meters being reported to the host as parameter changes, which made hosts such as Bitwig mark the project modified and constantly override the last-touched parameter
- User presets: storage deduplicated in the shared framework layer
v1.0.0 2026-08-16
- Initial public release
- Brown (E-series) and Black (G-series) voicings, each independently measured and calibrated
- 4-band EQ (LF/LMF/HMF/HF) with switchable Bell/Shelf on LF and HF, adjustable Q on LMF/HMF
- High-pass and low-pass filters
- 1x/2x/4x oversampling for cramp-free high-frequency response
- Real-time pre/post FFT spectrum analyzer
- 14 factory presets plus a user preset library
- Resizable interface
- Crash logs are now captured; the supporters overlay has an "Open crash log folder" link