default_eq

default_eq is designed to be your go-to EQ for tonal shaping, dynamic control, and adding harmonic character exactly where you need it.

Built around eight fully independent bands, it combines parametric and dynamic EQ, per-band saturation, Linear Phase processing, two Auto Gain modes, L/R, M/S and transient/sustain routing, and a real-time spectrum analyzer in a compact interface.

Most editing happens directly on the analyzer:

• Click empty space to create a filter: Bell in the middle, Low Shelf in the upper left, High Shelf in the upper right, High Cut in the lower left, or Low Cut in the lower right.
• Shift-click empty space to create Tilt, except in the lower far-left and far-right areas, which create resonant High Cut and Low Cut respectively.
• Cmd-drag a band to adjust Drive; Shift-drag it to adjust the dynamic Threshold.
• Use the mouse wheel for Q (or Slope on non-resonant Cut filters), Shift-wheel for placement, Alt-wheel for Slope, and Cmd-wheel for Character.
• Shift-click individual bands to add or remove them from the selection. Shift-drag or right-drag a marquee over empty graph space to select multiple bands.
• Alt-click a band to momentarily solo it; Cmd-click toggles bypass.
• Right-click a band to choose its filter, L/R–M/S–T/S placement, saturation mode, or reset the equalizer. Double-click a band to delete it.
• Shift-Cmd-click a band to reset its placement. Alt-right-click resets its Slope; Cmd-right-click resets its Drive and Character.
• For precise adjustments, Freq, Gain, Q, and Slope can also be entered via double-click directly in the parameter fields below.

There is deliberately no internal preset system. Plugin state is handled through the host, with complete project recall, versioned state, and Undo/Redo support.

Thanks and third-party code

• FreeEQ8 by GareBear99, providing the GPLv3 core equalizer DSP and logic.
• ZLEqualizer by ZL-Audio, providing AGPLv3 filter design and analyzer architecture.
• ZLSplitter by ZL-Audio, providing AGPLv3 transient/sustain separation.
• Faust Libraries vaeffects.lib by Dario Sanfilippo and Faust Libraries contributors, providing MIT-licensed matched-filter coefficient code used by de-cramping.

Exact repositories, revisions, licences, modifications, and code boundaries are documented in THIRD_PARTY_NOTICES.md. Included license texts are in LICENSES/.

Build

git submodule update --init --recursive

cmake -S . -B build -G "Unix Makefiles" \
  -DCMAKE_BUILD_TYPE=Release \
  -DDEFAULT_EQ_BUILD_TESTS=ON \
  -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64"

cmake --build build --config Release -j 8
ctest --test-dir build --output-on-failure

On Windows and Linux, omit CMAKE_OSX_ARCHITECTURES. AU is built only on macOS.

Licence

default_eq is open source under AGPL-3.0-only.

FreeEQ8-derived portions retain their GPL-3.0-only notices and are combined with the project under GPLv3 section 13.

See LICENSE.md, LICENSES/, and THIRD_PARTY_NOTICES.md.

Copyright (C) 2026 icanseesounds and upstream copyright holders.