THE FREEEQ8 MANIFESTO: A NEW STANDARD FOR AUDIO DSP

June 30, 2026 · View on GitHub

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_{⭐ Featured / submitted on — full tracker →}

FreeEQ8 is a professional-grade EQ8 / EQ Eight inspired parametric equalizer, free and open-source 8-band parametric EQ plugin for macOS, Linux, and Windows. Linear phase, dynamic EQ, match EQ, per-band drive, band linking, M/S processing, oversampling, and a real-time spectrum analyzer — all in a single, zero-cost plugin. Built with JUCE for VST3 and AU.

ProEQ8 is one of the most advanced EQs available, competing directly with top tools like ZL EQ and TDR Nova.

Works with Reaper! Tested and built on Ableton 10+

🗂️ Release Vault — official monetized releases, distributed tracks, and catalog proof
🗂️ Release Vault Repo: https://github.com/GareBear99/TizWildin-Release-Vault

⬇️ Download Now — Free

FabFilter Pro-Q alternative for $0–$20

2min Demo ProEQ8 is included!

All releases →

Is FreeEQ8/ProEQ8 the "Best"?

Yes, it is the best value EQ under $50, and arguably the best all-in-one creative EQ for budget-conscious producers. However, it is not the absolute best for pure surgical precision or workflow speed compared to industry standards "Best", Yet...

When factoring in the Pro version (ProEQ8 24Bands), the answer of quality shifts: FreeEQ8 is no longer the "best" for professional, unrestricted workflows, but the $20 upgrade makes the combined package arguably the best value EQ under $50, though it still trails paid industry standards in band count.

COMING SOON!!!

🔊 Trademark Sound

BaisMaed — play / download Collab sound with - YUME/GR!EF

💫 Thanks to our supporters

Final Verdict (June 2026)

Free Version: Currently Close But Not the absolute best yet. The 8-band limit and export cap make ZL Equalizer 2 the superior choice for zero-cost professional work. Pro Version ($20): The Best Value. By unlocking the 24-band SVF engine, it becomes the most capable "all-in-one" mixing tool for under $50. It is the best choice for producers who want to replace both their main EQ and a saturation plugin with a single $20 purchase. The Next engine will support a new form of quantum processing that will make it the 'Best' and that is why I put these here..

Is ProEQ8 ($20) the Best Value? Yes.

The ProEQ8 upgrade fundamentally changes the plugin's standing by unlocking the 24-band engine. 24-Band Architecture: The Pro version switches to a SIMD-vectorized State Variable Filter (SvfBandArray.h with AVX2/SSE2/Neon), matching the band count of FabFilter Pro-Q 4 and ZL Equalizer 2.

Unique Feature Set:

It is the only EQ under $50 combining:

24 Bands (Dynamic & Static)
Linear Phase mode
Per-Band Saturation (Tube, Tape, Transistor, Tanh)
Match EQ, Band Linking, and Collision Detection

Value:

At $20, it offers a feature set that rivals plugins costing $199, making it the best budget all-in-one mixing tool (EQ + Saturation + Dynamics).

📊 Current Status


Product	FreeEQ8 — free/open-source 8-band parametric EQ
Formats	VST3 · AU · Standalone
Platforms	macOS (universal) · Windows · Linux
Version	v2.3.0 (stable)
License	GPL-3.0

Tested in: Ableton Live 10+, REAPER, Logic Pro, FL Studio, Bitwig

Featured by: Rekkerd.org · AudioApp.cn · Midifan.com

Listed on: OpenAudio · awesome-music-production · Awesome Audio Dev List

THE FREEEQ8 MANIFESTO: A NEW STANDARD FOR AUDIO DSP

For decades, the audio software industry has been trapped in a loop of diminishing returns. Companies repackage the same foundational digital signal processing, wrap it in a sleek user interface, and market it as a groundbreaking revolution. It is the same math, dressed up nice enough to capture a following - a cycle that has largely dominated the industry standard since the release of Serum.

FreeEQ8 breaks that cycle.

FreeEQ8 isn't just another equalizer; it is an open disruption that redefines the relationship between product development, academic transparency, and commercial value in the audio space.

RADICALLY TRANSPARENT MATHEMATICS

While commercial developers guard their algorithms behind proprietary black boxes to justify steep price tags, FreeEQ8 lays its architecture completely bare.

Open-Source Academics: Every equation, filter coefficient derivation, and DSP optimization is provided with rigorous, in-depth academic clarity.
The New Baseline: By giving this math away for free, the baseline for what a consumer should expect out of a professional audio utility has been permanently elevated.

PEAK ENGINE TOPOLOGY

FreeEQ8 is engineered using the absolute peak of known mathematical constants implemented in tandem with high-performance, deterministic engine topology states. It represents the logical ceiling of standard digital equalization.

THE NEW MARKET REALITY: To charge money for an equalizer moving forward, a developer can no longer just copy the classics. They now have to prove their software is mathematically superior to the industry giants (the GOATs) AND superior to the baseline established by FreeEQ8. If it isn't, it doesn't deserve a price tag.

A FOUNDATION FOR PIONEERS

This project is an explicit challenge to the audio engineering community to stop repeating the past. By open-sourcing a peak-tier DSP framework, the groundwork is officially laid for the next generation of pioneers to push the boundaries of sound.

Instead of wasting time rebuilding the wheel and re-dressing old concepts, developers can finally take this foundation and leap forward into genuine audio innovation.

📰 Press & Coverage

Outlet	Article
Rekkerd.org	FREE: FreeEQ8 parametric EQ effect plugin by Gary Doman
AudioApp.cn	福利：Gary Doman 推出 FreeEQ8 免费开源参量均衡器
Midifan.com	FreeEQ8 免费开源参量均衡器

📄 Publications

Title	Venue	Status
Real-Time State-Space Parameterization in Digital EQ	DAFx / AES	📝 Preprint

🏫 DAFx26 Demo Track (MIT, September 2026) — Submitted May 29, 2026 (#109)

🎁 TizWildin Hub

Tracking our first 1,200 users — at 1,000 we'll run giveaways (ProEQ8 keys, sample packs, early access).

Full submission tracker: docs/FEATURED_ON.md · docs/SUBMISSIONS_2026.md

FreeEQ8 in Ableton Live

🆚 How FreeEQ8 Compares

Feature	FreeEQ8	FabFilter Pro-Q 4	ZL Equalizer 2	TDR Nova
Price	Free	$199	Free	Free
Open Source	GPL-3.0	—	AGPL-3.0	—
Bands	8	24	24	4 + HP/LP
Dynamic EQ	✓ (thresh / ratio / atk / rel)	✓	✓	✓
Linear Phase	✓	✓	✓	—
Match EQ	✓	✓	✓ (WIP)	—
Mid/Side	✓ (per-band)	✓	✓	— (free)
Per-Band Drive	✓ (tanh saturation)	—	—	—
Band Linking	✓ (groups A/B)	—	—	—
Oversampling	✓ (1×–8×)	internal	—	—
Adaptive Q	✓	—	—	—
Spectrum Analyzer	✓ (4096-pt FFT)	✓	✓	✓
Level Meter	✓ (peak + RMS)	—	—	—
Undo / Redo	✓	✓	✓	—
Collision Detection	✓ (Pro)	✓	✓	—
Surround / Atmos	—	✓	—	—
Formats	VST3, AU	VST3, AU, AAX, CLAP	VST3, AU, LV2	VST3, AU, AAX

FreeEQ8 is the only free EQ that combines linear phase + dynamic EQ + match EQ + per-band saturation + band linking in one plugin.

⚡ ProEQ8 — Available Now ($20)

Love FreeEQ8? ProEQ8 takes everything further.

ProEQ8 is the commercial big brother of FreeEQ8 — same rock-solid DSP engine, massively expanded. Included in the latest release download.

	FreeEQ8 (Free)	ProEQ8 ($20)
Bands	8	24
Saturation Modes	tanh	Tube · Tape · Transistor · Tanh
A/B Comparison	—	✓ (instant snapshot toggle)
Auto-Gain Bypass	—	✓ (RMS-matched)
Piano Roll Overlay	—	✓ (note frequency reference)
Collision Detection	—	✓ (overlapping band warnings)
Factory Presets	30	30+ (genre-specific)
Dynamic EQ	✓	✓
Linear Phase	✓	✓
Match EQ	✓	✓
Mid/Side	✓	✓
Oversampling	✓	✓
Band Linking	✓	✓
Formats	VST3, AU	VST3, AU

ProEQ8 is included in the macOS DMG download. A license key is required to unlock it — purchase through the link above to receive your key via email. Without a license, ProEQ8 runs in demo mode: 2 minutes of clean playback, then a 30-second mute window (repeats).

🧠 Smart EQ Layer (shipped v2.2.3–2.2.4)

FreeEQ8 includes a real-time decision layer on top of the existing 8-band engine — not to replace surgical control, but to make getting to a clean mix faster than most paid EQs.

Shipped:

Source/DSP/ResonanceDetector.h — log-frequency peak finder that produces up to 4 ranked suggestion bands with recommended frequency, cut-gain, Q, confidence score, and a semantic label ("mud", "boxiness", "harshness", "sibilance" …).
Source/DSP/IntentMode.h — behavioural biasing: None / Vocal Clean / Drum Punch / Guitar Space / Master Polish. Each mode shifts the detector’s scoring curve toward the frequency zones that matter for that source, without forcing preset bands.
Source/DSP/FrequencyExplainer.h — static frequency → semantic description map powering the Explain-on-hover UX (“Cutting mud (320 Hz)” / “Adding air (12 kHz)”).
intent_mode APVTS parameter — host-automatable, wired to editor dropdown.
Glowing suggestion-node overlay on the response curve (amber rings, confidence-scaled opacity).
One-click “apply suggestion” — drops a detected peak into the next unused band via APVTS (undo-able).
Explain-on-hover popup when mousing over any band or suggestion node.
Pre-ring warning overlay when DrumPunch + Linear Phase are active simultaneously.
Deterministic, allocation-free, UI-thread safe — piggybacks on the existing triple-buffered SpectrumFIFO.

Coming next:

Zero-Lag auto-switch between linear-phase (precision) and minimum-phase (real-time)

No other free open-source 8-band EQ currently combines intent-aware resonance detection + explain-on-hover + one-click apply. See docs/SMART_EQ_LAYER.md for the full algorithm and status matrix.

🔍 Code Audit

A full line-by-line audit of the DSP, threading, and restriction system is published at AUDIT.md. Summary: FreeEQ8 has zero feature locks and zero nag interruptions during real-time playback. Offline export is limited to 4 minutes 30 seconds (ProEQ8 removes this limit). All bug fixes through v2.2.5 are documented with root cause analysis.

📊 Benchmarks & RT-safety

FreeEQ8 / ProEQ8 v2.2.5 ships with a proven real-time-safe DSP engine:

Zero heap allocation on the audio thread for any user action (pooled oversamplers).
Canonical swap-chain triple-buffer for both the spectrum FIFO and the linear-phase FIR kernel — verified under concurrent stress (3 runs × 400 ms, ~600 M samples, 0 tears).
Linear-phase FIR rebuild on a dedicated juce::Thread — no FFT work on the audio thread.
MatchEQ chunking handles DAW blocks of any size (previously dropped on n > fftSize).

Full evidence and numbers:

Milestone A report — math, benchmarks, stress-test results, sonic-impact analysis.
v2.2.0 release readiness — what's verified green/yellow/red.
Tests/AuditBench.cpp — reproducible micro-benchmarks (clang -O3 -DNDEBUG -pthread).
Tests/AuditRegressionTest.cpp — concurrent-stress invariants for the triple-buffer + chunking patterns.

✨ Features

Core EQ

8 Independent Bands — full parametric control (frequency, Q, gain)
6 Filter Types per band: Bell, Low Shelf, High Shelf, High Pass, Low Pass, Bandpass
Multiple Slopes — 12 / 24 / 48 dB/oct via cascaded biquad stages
Per-Band Enable/Disable & Solo for A/B comparison and audition
Parameter Smoothing (20ms linear interpolation, coefficients refreshed every 16 samples during parameter automation; every sample when Dynamic EQ is active)

Advanced Processing

Linear Phase Mode — symmetric FIR from combined biquad magnitude, overlap-add FFT convolution (2048-sample latency when active)
Dynamic EQ — per-band envelope follower with sidechain bandpass, threshold, ratio, attack & release
Per-Band Saturation / Drive — gain-compensated tanh waveshaper (0–100%)
Mid/Side Processing — M/S encode/decode with per-band channel routing (Both / L-Mid / R-Side)
Oversampling — 1x / 2x / 4x / 8x using JUCE polyphase IIR half-band filters
Band Linking — link groups A/B propagate frequency (ratio), gain & Q (delta) changes
Match EQ — capture a reference spectrum, analyze current signal, compute & apply per-bin correction via FFT
Adaptive Q — automatically widens Q with increasing gain

Visualization & UI

Real-Time Spectrum Analyzer — 4096-point FFT, Hann window, pre/post EQ toggle
Interactive Response Curve — composite + per-band colored curves with dB/frequency grid
Draggable Band Nodes — click-drag for freq/gain, shift+drag for Q, right-click context menu
Stereo Level Meter — peak hold + RMS display
Selected-Band Paradigm — 8 colored band buttons, single set of controls rebound per selection
Dark Theme — resizable UI (750×550 to 1400×900)

Global Controls

Output Gain (-24 dB to +24 dB)
Scale (0.1x to 2x) — scales all band gains simultaneously
Preset System — save / load / delete, 30 factory presets
Undo / Redo — integrated with JUCE UndoManager via APVTS
State Save/Restore — all settings persist in your DAW project

DSP Specifications

Stereo processing (or Mid/Side)
Sample rates: 44.1 kHz to 192 kHz+
Dual filter topology: RBJ TDF-II biquad (FreeEQ8) + Simper SVF via trapezoidal integration (ProEQ8) — modulation-stable Dynamic EQ
Double-precision (64-bit) internal arithmetic, float I/O
Zero latency in minimum-phase mode; linear phase adds 2048 samples
0.62% single-core CPU budget at 44.1 kHz (SVF 8-band stereo, 161× headroom)
Low CPU usage (disable unused bands, lower oversampling to reduce load)

Compatibility

macOS: 10.13 High Sierra and later (universal binary: Intel + Apple Silicon)
Linux: Debian/Ubuntu 20.04+ (VST3 only; see build instructions for dependencies)
Windows: 10 and later (64-bit)
DAWs tested: Ableton Live 10+, Logic Pro, FL Studio, Bitwig, REAPER
Formats: VST3, AU (macOS), Standalone (all platforms)

🚀 Quick Start

macOS

git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
./build_macos.sh

Linux (Debian/Ubuntu)

git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
./build_linux.sh          # installs deps via apt, then builds

Windows

git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8
.\build_windows.ps1

Plugins will be automatically installed to your system plugin directories.

📋 Build Instructions

Prerequisites

macOS

Xcode Command Line Tools: xcode-select --install
CMake 3.15+: brew install cmake

Linux (Debian/Ubuntu)

GCC 9+ or Clang 10+
CMake 3.15+
JUCE system dependencies (installed automatically by build_linux.sh): libasound2-dev libjack-jackd2-dev libfreetype6-dev libx11-dev libxcomposite-dev libxcursor-dev libxext-dev libxfixes-dev libxinerama-dev libxrandr-dev libxrender-dev libwebkit2gtk-4.0-dev

Windows

Visual Studio 2019+ with C++ build tools
CMake 3.15+

Detailed Build Steps

1. Clone with JUCE Submodule

git clone --recursive https://github.com/GareBear99/FreeEQ8.git
cd FreeEQ8

If you already cloned without --recursive:

git submodule update --init --recursive
cd JUCE && git checkout 7.0.12 && cd ..

2. Build

macOS:

chmod +x build_macos.sh
./build_macos.sh

Linux:

chmod +x build_linux.sh
./build_linux.sh

Windows:

.\build_windows.ps1

3. Plugin Installation

macOS (automatic):

VST3: ~/Library/Audio/Plug-Ins/VST3/FreeEQ8.vst3
AU: ~/Library/Audio/Plug-Ins/Components/FreeEQ8.component

Linux (manual):

Copy build/FreeEQ8_artefacts/Release/VST3/FreeEQ8.vst3 to ~/.vst3/

Windows (manual):

Copy build\FreeEQ8_artefacts\Release\VST3\FreeEQ8.vst3 to:
- C:\Program Files\Common Files\VST3\

4. Rescan in Your DAW

Ableton Live: Preferences → Plug-ins → Rescan
Logic Pro: Automatic detection
FL Studio: Options → Manage plugins → Find plugins

🎛️ Usage Guide

Parameter Ranges

Parameter	Range	Scale	Description
Frequency	20 Hz – 20 kHz	Logarithmic	Center/cutoff frequency
Q	0.1 – 24	Logarithmic	Bandwidth (0.1 = wide, 24 = narrow)
Gain	-24 dB to +24 dB	Linear	Boost/cut amount
Slope	12 / 24 / 48 dB/oct	Discrete	Filter steepness (1/2/4 cascaded stages)
Drive	0 – 100 %	Linear	Per-band tanh saturation amount
Channel	Both / L-Mid / R-Side	Discrete	Per-band channel routing
Link Group	-- / A / B	Discrete	Band linking group
Dyn Threshold	-60 dB to 0 dB	Linear	Dynamic EQ threshold
Dyn Ratio	1:1 – 20:1	Logarithmic	Dynamic EQ compression ratio
Dyn Attack	0.1 – 100 ms	Logarithmic	Dynamic EQ attack time
Dyn Release	1 – 1000 ms	Logarithmic	Dynamic EQ release time
Output	-24 dB to +24 dB	Linear	Master output level
Scale	0.1x – 2x	Linear	Global gain multiplier

Common EQ Techniques

Surgical EQ (Problem Frequency Removal)

Band: Bell filter
Q: 6-12 (narrow)
Gain: -6 to -12 dB

Musical EQ (Broad Tonal Shaping)

Band: Bell/Shelf filter
Q: 0.5-2 (wide)
Gain: ±3 to ±6 dB

High-Pass Filtering

Band: HighPass filter
Freq: 20-120 Hz (depends on source)
Q: 0.7 (standard)

Example Settings

Kick Drum:

Band 1: Bell @ 60Hz, Q=1.5, +4dB (sub thump)
Band 2: Bell @ 200Hz, Q=3, -3dB (cardboard removal)
Band 3: Bell @ 3kHz, Q=2, +2dB (beater click)

Acoustic Guitar:

Band 1: HighPass @ 80Hz (rumble removal)
Band 2: Bell @ 200Hz, Q=1.5, -2dB (boominess)
Band 3: Bell @ 3kHz, Q=1, +3dB (presence)
Band 4: HighShelf @ 8kHz, +2dB (air)

Vocals:

Band 1: HighPass @ 80Hz (rumble)
Band 2: Bell @ 250Hz, Q=2, -3dB (muddiness)
Band 3: Bell @ 1kHz, Q=1, +2dB (body)
Band 4: Bell @ 5kHz, Q=2, +3dB (clarity)

🔧 Technical Details

Architecture

┌──────────────────────────────────────────────────────┐
│               FreeEQ8 Audio Processor                │
├──────────────────────────────────────────────────────┤
│  Input Buffer (Stereo)                               │
│          ↓                                           │
│  Spectrum FIFO (pre-EQ) ──→ UI spectrum display      │
│          ↓                                           │
│  ┌─── IF linear_phase ───┐  ┌── ELSE (min-phase) ──┐│
│  │ Build composite mag   │  │ Oversampling ↑ (opt.) ││
│  │ response from biquads │  │       ↓               ││
│  │       ↓               │  │ M/S Encode (optional) ││
│  │ FIR convolution       │  │       ↓               ││
│  │ (overlap-add FFT,     │  │ Per-band loop ×8:     ││
│  │  4096-tap, 8192 FFT,  │  │  ├ Dyn EQ envelope    ││
│  │  2048-sample latency) │  │  ├ Smooth + update    ││
│  │       ↓               │  │  │  coefficients      ││
│  │ Output Gain           │  │  ├ Cascaded biquads   ││
│  └───────────────────────┘  │  │  (1/2/4 stages)    ││
│                              │  └ Drive (tanh)       ││
│                              │       ↓               ││
│                              │ Output Gain & Scale   ││
│                              │       ↓               ││
│                              │ M/S Decode (optional) ││
│                              │       ↓               ││
│                              │ Oversampling ↓ (opt.) ││
│                              └───────────────────────┘│
│          ↓                                           │
│  Match EQ correction (FFT overlap-add, optional)     │
│          ↓                                           │
│  Spectrum FIFO (post-EQ) ──→ UI spectrum display     │
│          ↓                                           │
│  Output Metering (peak hold + RMS)                   │
│          ↓                                           │
│  Output Buffer (Stereo)                              │
└──────────────────────────────────────────────────────┘

DSP Implementation

Filter Structure: Transposed Direct Form II biquad (Biquad.h) + Simper SVF (SvfBiquad.h) with tan() pre-warp
Coefficient Calculation: RBJ Audio EQ Cookbook (FreeEQ8) / Cytomic SVF (ProEQ8)
Smoothing: Linear interpolation over 20ms
Update Rate: Coefficients refreshed every sample when Dynamic EQ is active; every 16 samples during parameter smoothing (amortised cost). Variable-cadence engine (v2.2.3) batches to 4-sample intervals during stable envelopes.
Precision: Double-precision (64-bit) coefficients and internal state; float I/O
Linear Phase: 4096-tap symmetric FIR, 8192-point FFT, overlap-add convolution
Dynamic EQ: One-pole envelope follower with sidechain bandpass at band frequency
Spectrum: 4096-point FFT, Hann window, lock-free SPSC FIFO
SIMD Scaffold: SvfBandArray<8> with AVX2/SSE2/Neon dispatch (v2.2.4)

Project Structure

FreeEQ8/
├── Source/
│   ├── PluginProcessor.h/.cpp     # Main audio processor
│   ├── PluginEditor.h/.cpp        # UI editor & layout
│   ├── Config.h                   # Product config (FreeEQ8 vs ProEQ8)
│   ├── DSP/
│   │   ├── Biquad.h               # RBJ biquad filter (FreeEQ8 path)
│   │   ├── SvfBiquad.h            # Simper SVF filter (ProEQ8 path)
│   │   ├── SvfBandArray.h         # SIMD-vectorised SVF (AVX2/SSE2/Neon)
│   │   ├── EQBand.h               # EQ band with smoothing, drive & dynamic EQ
│   │   ├── SpectrumFIFO.h         # Lock-free SPSC triple-buffer FFT FIFO
│   │   ├── LinearPhaseEngine.h    # FIR-based linear-phase EQ engine
│   │   ├── NaturalPhaseEngine.h   # 256-tap natural-phase mode
│   │   ├── MatchEQ.h              # Reference capture & correction curve
│   │   ├── ResonanceDetector.h    # Allocation-free resonance peak finder
│   │   ├── IntentMode.h           # Vocal/Drum/Guitar/Master weighting
│   │   └── FrequencyExplainer.h   # Semantic frequency → label map
│   ├── UI/
│   │   ├── ResponseCurveComponent.h/.cpp  # EQ curve + spectrum + nodes
│   │   └── LevelMeter.h           # Stereo peak/RMS level meter
│   ├── Presets/
│   │   └── PresetManager.h/.cpp   # Preset save/load system
│   ├── UpdateChecker.h            # GitHub releases update checker
│   └── LicenseValidator.h         # License + demo + export limit
├── Tests/
│   ├── BiquadTest.cpp             # RBJ coefficient correctness
│   ├── SvfTest.cpp                # SVF correctness (11 assertions)
│   ├── AuditRegressionTest.cpp    # Triple-buffer + chunking stress tests
│   └── AuditBench.cpp             # RT-safety micro-benchmarks
├── server/
│   ├── stripe-webhook.js          # Cloudflare Worker for Stripe → license
│   ├── wrangler.toml              # Wrangler deployment config
│   └── package.json               # Server dependencies (wrangler)
├── PAPER.md                       # Technical paper (DAFx/AES submission)
├── BENCHMARK.md                   # Full benchmark results & methodology
├── AUDIT.md                       # Line-by-line code audit report
├── ROADMAP_2_5_PLUS.md            # Long-horizon roadmap through v2.3.0
├── STRIPE_SETUP.md                # ProEQ8 Stripe deployment guide
├── FeatureBench.cpp               # Standalone benchmark suite (no JUCE)
├── CMakeLists.txt                 # CMake config (FreeEQ8 + ProEQ8 targets)
├── docs/                          # Screenshots & assets
├── JUCE/                          # JUCE framework (submodule)
└── build/                         # Build output (ignored)

🛣️ Roadmap

v0.4.0

Real-time spectrum analyzer
Interactive frequency response curve display
Draggable band nodes on curve
Adaptive Q implementation
Band solo/audition mode
Preset management system

v0.5.0

Multiple filter slopes (12/24/48 dB/oct) via cascaded biquads
Mid/Side processing mode with M/S encode/decode
Per-band channel routing (Both / L-Mid / R-Side)
Oversampling options (1x, 2x, 4x, 8x)
Output metering with peak hold and RMS
Resizable UI (700×500 to 1400×900)

v1.0.0

Linear phase mode (FIR convolution via overlap-add FFT)
Dynamic EQ capabilities (per-band envelope follower with threshold/ratio/attack/release)
Band linking (link groups A/B with delta-based freq/gain/Q propagation)
Per-band saturation/drive (gain-compensated tanh waveshaper)
Undo/Redo system (integrated with APVTS UndoManager)
Match EQ functionality (capture reference spectrum, compute & apply correction)

v2.0.0

Online license activation (2 devices per key) with Stripe checkout
ProEQ8 commercial target (24 bands, 4 saturation modes, A/B, auto-gain)
Cloudflare Worker license server + Resend email delivery
Demo mode for unactivated ProEQ8 (2 min clean + 30 s mute cycle)

v2.1.0

Standalone app included in all platform packages
Hardened ProEQ8 license: device-bound activation, 7-day re-verify, 30-day offline grace
Server /verify endpoint for periodic re-validation
Obfuscated signing secret in binary
Fixed JUCE 7.0.12 API compatibility

v2.2.0

Real-time safety: zero heap allocation on the audio thread for any user action (Milestone A / A1)
SpectrumFIFO + LinearPhaseEngine kernel on canonical swap-chain triple-buffer (A4 / A5)
Linear-phase FIR rebuild moved to a dedicated juce::Thread worker (A5)
MatchEQ::applyCorrection handles arbitrarily large DAW blocks instead of silent early-return (A3)
Editor modal dialogs + license HTTP callbacks are lifetime-safe via juce::WeakReference (A2)
Demo cadence: 2 minutes of clean playback + 30-second mute window
getTailLengthSeconds reports the MatchEQ overlap-add tail for offline renders (A7)

v2.2.1–2.2.2

Transistor saturation gain bug fixed (ProEQ8)
Dynamic EQ zero-lag coefficient update when dynEnabled
MatchEQ `correctionGain[]$ \text{precompute} (3 \times \text{throughput} \text{improvement})
[\text{x}] \text{Simper} \text{SVF} \text{engine} ($SvfBiquad.h`) — modulation-stable SVF, trapezoidal integration

v2.2.3–2.2.4

v2.2.5

Transistor saturation invD*d no-op bug fixed in shipped code
MatchEQ hot-path pow() eliminated — correctionGain[] precompute
SvfTest.cpp correctness suite (11 assertions, all passing)
FreeEQ8 export limit (4:30 offline render)
Version consistency across all docs (no fake v2.4/v2.5/v3.0 refs)
PAPER.md section numbering fixed (§6 Benchmarks, §8 Compact View, §9 Future Work)

v2.3.0 (Current Release) — Stable Release

Version alignment (CMakeLists.txt + Config.h both 2.3.0)
Get Pro button for FreeEQ8 (opens ProEQ8 checkout)
Full codebase audit completed
Smart EQ layer documentation expanded in PAPER.md
CI/CD fixes (Linux webkit2gtk-4.1, Windows MSVC lambda capture, macOS retry)
Build verified (AU, VST3, Standalone) on all platforms

v2.4.0 (Planned) — ProEQ8 Launch

SVF wired into EQBand via #if PROEQ8
24-band layout
Zero-Lag auto-switch between linear-phase and minimum-phase modes
Stripe checkout live
Cross-instance ARC-Core spine

🤝 Contributing

Contributions are welcome! Here's how you can help:

Fork the repository
Create a feature branch: git checkout -b feature/amazing-feature
Commit your changes: git commit -m 'Add amazing feature'
Push to the branch: git push origin feature/amazing-feature
Open a Pull Request

Development Guidelines

Follow existing code style
Add comments for complex DSP algorithms
Test on both macOS and Windows if possible
Update documentation for new features

Areas for Contribution

🎨 UI/UX improvements
🔊 Additional filter types
🐛 Bug fixes and optimizations
📚 Documentation improvements
🧪 Unit tests

NOT affiliated with, endorsed by, or derived from Ableton AG
NOT a clone of Ableton's EQ Eight
An independent, open-source project
Built using public-domain DSP algorithms (RBJ Audio EQ Cookbook)

📊 Benchmarks

Every feature claim is backed by a reproducible standalone benchmark suite. All features pass at >10x CPU headroom at 44.1 kHz / 512-sample blocks.

Key numbers (g++ -O3, x86-64, median of 16 trials):

Feature	ns/sample	Headroom
Single biquad band (Bell)	5.1	>2200x
8-band stereo full path	41.5	>273x
Dynamic EQ (per-sample, zero-lag)	68.3	>166x
Linear phase FIR rebuild	36.5 µs/event	background thread
Match EQ correction (v2.2.1)	2.8	>4000x
Match EQ correction (old naive pow)	7.4	1527x
Mid/Side encode+decode	0.42	>27,000x
SpectrumFIFO push (audio thread)	0.66	>17,000x
Oversampling 8x EQ cost	213	>53x
Tanh saturation (stereo)	61.4	>184x

→ Full results and methodology: BENCHMARK.md

Build and run the benchmarks yourself (no JUCE required):

g++ -std=c++17 -O3 -DNDEBUG -pthread Tests/FeatureBench.cpp -o FeatureBench -I.
./FeatureBench

🐛 Known Issues

Changing oversampling mid-playback may cause a brief click (IIR half-band filter state differs between orders; reset on switch)
Linear phase mode adds 2048 samples of latency (reported to the DAW via setLatencySamples)
Match EQ capture is mono-summed; correction is applied per-channel
Linear phase mode does not apply M/S, per-band drive, or dynamic EQ — those features require per-sample biquad state and are on the minimum-phase path only. The oversampling selector and the affected controls are greyed out in the UI when linear phase is active

Fixed in v2.2.1:

~~Transistor saturation gain error~~ (ProEQ8) — double-multiply bug caused ~d× level at high drive; fixed
~~Dynamic EQ coefficient lag~~ — up to 16-sample transient lag between envelope detection and filter response; now zero-lag when Dynamic EQ is enabled
~~Linear phase + oversampling undocumented interaction~~ — behaviour now explicitly documented in source

Report issues at: https://github.com/GareBear99/FreeEQ8/issues

💡 Tips & Tricks

Performance Optimization

Disable unused bands to reduce CPU load
Use wider Q values (lower numbers) for smoother processing
Enable adaptive Q for automatic gain-dependent Q adjustment

Mixing Workflow

Start with subtractive EQ (cut problem frequencies)
Use narrow Q to identify resonances
Use wide Q for musical boosts
Check your EQ in mono to avoid phase issues

Sound Design

Stack multiple bell filters at the same frequency with different Q values
Automate the scale parameter for dramatic filter sweeps
Use extreme Q values (>10) for creative resonances

🙏 Acknowledgments

JUCE Framework - Cross-platform audio plugin framework
Robert Bristow-Johnson - RBJ Audio EQ Cookbook
Audio Plugin Development Community - For knowledge sharing
Ableton - For inspiration (not affiliation)

💖 Support the Project

FreeEQ8 is free and open source. If it's useful to you, consider supporting development:

Other ways to help:

⭐ Star this repo — helps others find FreeEQ8
🐛 Report bugs — open an issue
🔀 Contribute — PRs are welcome
📣 Spread the word — tell a producer friend

📧 Contact

Issues: GitHub Issues
Discussions: GitHub Discussions
Email: neovectr.inc@gmail.com

Other Projects by Me!

https://github.com/GareBear99/TizWildinEntertainmentHUB

https://github.com/GareBear99/awesome-audio-plugins-dev

https://github.com/GareBear99/PaintMask_Free-JUCE-Plugin

https://github.com/GareBear99/WURP_Toxic-Motion-Engine_JUCE

https://github.com/GareBear99/RiftWaveSuite_RiftSynth_WaveForm_Lite

https://github.com/GareBear99/AETHER_Choir-Atmosphere-Designer

https://github.com/GareBear99/WhisperGate_Free-JUCE-Plugin

https://github.com/GareBear99/Therum_JUCE-Plugin

https://github.com/GareBear99/MixMaid

https://github.com/GareBear99/BassMaid

https://github.com/GareBear99/SpaceMaid

https://github.com/GareBear99/GlueMaid

https://github.com/GareBear99/XyloCore

Built with ❤️ by Gary Doman (GareBear99/TizWildin)

"Great sound shouldn't cost anything"

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Tester Call

FreeEQ8 is looking for real-world DAW testers.

Please test the latest release in your DAW and report compatibility feedback here:

https://github.com/GareBear99/FreeEQ8/issues/new?template=tester-feedback.yml

Helpful feedback includes OS, DAW, plugin format, what worked, what broke, and steps to reproduce.

See the full tester call:

https://github.com/GareBear99/FreeEQ8/blob/main/docs/testing/TESTER_CALL.md