Quad Morph Filter

June 13, 2026 · View on GitHub

Release License JUCE Platform Downloads

⚠️ IMPORTANT: Audio Safety Notice

This plugin can generate LOUD audio output. HEARING PROTECTION IS YOUR RESPONSIBILITY.

  • Always monitor output levels carefully when using speakers or headphones
  • Start with LOW volume and gradually increase
  • NEVER wear headphones at maximum volume
  • Take regular breaks during extended use
  • Prolonged exposure to loud sound (≥85 dB SPL) causes permanent hearing loss
  • By using this plugin, you assume FULL responsibility for your hearing safety and equipment protection

For detailed safety information, see the Disclaimer section.

Overview

Quad Morph Filter is a high-performance, open-source VST3 plugin featuring 28 meticulously modeled filter algorithms that can be morphed together in real-time using an intuitive XY pad interface. Designed for advanced sound design, electronic music production, and experimental audio processing, Quad Morph Filter delivers professional-grade DSP with research-backed filter implementations ranging from iconic analog classics (Moog Ladder, TB-303) to cutting-edge digital algorithms (Z-Plane morphing, Bode frequency shifter).

Morph up to 4 different filters simultaneously with equal-power blending, control them via 19 LFO waveforms, record your own XY patterns, and explore infinite sonic territories — all in real time with extreme audio stability.

🎬 Demo Videos

Introduction (概要編)
Quad Morph Filter - Introduction

Advanced Techniques (応用編)
Quad Morph Filter - Advanced Techniques

Key Features

🎛️ 28 Premium Filter Models

A comprehensive, handcrafted collection spanning 6 distinct filter architecture categories:

  • Ladder Filters (5 models): Iconic analog emulations including Moog Ladder, TB-303 Diode (with Accent control), Prophet CEM3320, Oberheim SSM 2040, and Roland Jupiter.
  • SVF Precision (9 models): High-precision State Variable Filters including Clean SVF, SEM, Formant (Vowel), Bitcrush/SRR, Comb Filter, MS-20 Screaming, Phaser, Wavefolder, and CS-80.
  • Analog Emulation (4 models): Sophisticated analog circuit simulators: Vactrol LPG, Modal Resonator, Nyquist Anti-alias, and FDN Reverb (4-delay feedback network).
  • Digital Precision (4 models): Mathematically perfect digital filters: Butterworth (flat passband), Chebyshev (ripple), Bessel (linear phase), and Elliptic (notch stopband).
  • Spectral (5 models): Advanced frequency-domain processing: Kilo All-Pass (16 stages), Bode Frequency Shifter (Hilbert transform), Z-Plane 2D Morph, Phased Array, and Phaser 2.
  • Experimental (1 model): All-Pass Phaser for texture and ambient effects.

🌊 Real-Time XY Morphing Engine

  • 4-Filter Simultaneous Blending: Morph between up to 4 different filter models at once with seamless, zero-artifact equal-power crossfading.
  • 4 Morph Blend Algorithms: Choose your blending curve — Equal Power (classic constant-energy), Linear (bilinear crossfade), Smoothstep (S-curve bias), or Radial (inverse-distance weighting).
  • Live Frequency Response Visualizer: Watch the composite filter curve update in real time as you morph. Disabled filters fade to silence (no -100dB artifacts).
  • Cutoff/Resonance Direct Control: Switch modes to control Cutoff and Resonance directly via XY position rather than morphing filters.

🎚️ Advanced LFO System

19 Waveforms:

  • Classic: Sine, Sawtooth, Pulse, Triangle
  • Random: Random 1/2, White Noise, Smooth Noise
  • Geometric: Spirograph, Torus Knot, Lissajous, Spiral, Star, Rose, Lemniscate
  • Dynamic: Billiard (collision bouncing), Polygon, Lorenz/Henon Attractor
  • Special: Recording (hand-drawn XY patterns)

3 Independent LFO Systems + Modulation Engines:

  • LFO1: Morphing parameter modulation (XY position)
  • LFO2: Cutoff frequency modulation
  • LFO3: Resonance modulation
  • LFO4: Rate Modulation (modulate LFO1/2/3 frequencies)
  • LFO5: Dry/Wet Range Modulation (control mix amount via LFO)

Precise Timing Control:

  • Tempo sync: 8/1 → 1/64 with Dot (1.5×) and Triplet (2/3×) variants
  • Freeform rate: 0.01 – 20.0 Hz
  • Per-LFO phase, fade-in time, and per-band spread controls

Recording & Playback:

  • Draw custom XY patterns directly on the morph pad via mouse
  • Tab-based LFO selection (LFO1/2/3) prevents recording confusion
  • Real-time grid visualization during capture
  • Lock-free atomic operations ensure audio thread safety

🔊 Professional Audio Features

  • Oversampling (4 modes): Off / Auto / 2× / 4× — crucial for Moog and TB-303 models to suppress aliasing under high resonance.
  • Envelope Follower: Sidechain-style input tracking with Depth and Invert controls.
  • Dry/Wet Mix: Smooth linear interpolation of wet/dry blend (τ = 50 ms) eliminates zipper noise under automation.
  • Master Output Gain: Professional-grade gain staging (-36 to +24 dB).
  • Limiter Ceiling: Transparent RMS-tracking limiter with adjustable ceiling threshold.
  • Automatic Gain Compensation (AGC): Moog and TB-303 models dynamically scale output to maintain perceived loudness under resonance boost.

🎨 Pro UI & Visualization

  • Ableton Live Medium-Dark Theme: Seamlessly integrated dark aesthetic matching professional production environments.
  • Real-Time Frequency Response Graph: 1024-point FFT display with 0 dB reference line, dB grid, and frequency markers (100 Hz, 1 kHz, 10 kHz).
  • E-Button (Background Randomizer): Click to randomize GUI background color; right-click to reset to default.
  • LFO Tab Navigation: Visual tabs to select which LFO is being edited or recorded — prevents accidental overwrites.
  • Parameter Smoothing: All slider changes are interpolated to eliminate clicks and pops.

Filter Models Guide

Complete Model Reference

Quad Morph Filter ships with 28 handcrafted filter models, each optimized for specific sonic characteristics. Select any combination of 4 filters to morph between:

Model #NameCategoryTypeSlopeDescription
0Clean SVFSVFLP/BP/HP/Notch12/24/48/96 dB/octPristine state-variable filter, zero aliasing
1Moog LadderLadderLP only24 dB/octClassic 4-pole tanh nonlinearity, Newton-Raphson iteration, ADAA
2TB-303 DiodeLadderLP only24 dB/octIconic acid synth filter with Accent Off/Low/High control
3SEM (Oberheim)SVFLP/BP/HP/Notch24 dB/octOberheim classic with soft clipping saturation
4Bitcrush/SRRSVFLP/BP/HP/Notch24 dB/octSample-rate reduction effect, ultra-lo-fi textures
5Formant (Vowel)SVFLP/BP/HP/Notch24 dB/oct3-parallel SVF array for vowel morphing
6Comb FilterSVFLP/BP/HP/Notch24 dB/octDelay-line comb with variable feedback
7MS-20 ScreamingSVFLP/BP/HP/Notch24 dB/octKorg MS-20 recreation with extreme resonance
8All-Pass PhaserSpectralLP/BP/HP/Notch24 dB/oct16-stage all-pass network, subtle phasing
9WavefolderSVFLP/BP/HP/Notch24 dB/octSine expansion with ADAA anti-aliasing
10FDN ReverbExperimentalLP/BP/HP/Notch24 dB/oct4-delay feedback network (Room/Hall/Cave/Plate)
11Kilo All-PassSpectralLP/BP/HP/Notch24 dB/oct16-stage all-pass cascade, dense modulation
12CEM3320 (Prophet)LadderLP only24 dB/octCurtis CEM3320 emulation with soft nonlinearity
13SSM 2040 (OB)LadderLP only24 dB/octOberheim classic with asymmetric soft clipping
14CS-80 (Yamaha)SVFLP/BP/HP/Notch24 dB/octLegendary polyphonic synth filter
15Jupiter (Roland)LadderLP only24 dB/octRoland SH-101 / Jupiter-8 diode ladder
16Phased ArraySpectralLP/BP/HP/Notch24 dB/octAll-pass phasing with stereo width control
17ButterworthDigitalPrecisionLP/BP/HP/Notch12/24/48/96 dB/octMaximally flat passband response
18ChebyshevDigitalPrecisionLP/BP/HP/Notch12/24/48/96 dB/octControlled passband ripple, sharp transition
19BesselDigitalPrecisionLP/BP/HP/Notch12/24/48/96 dB/octLinear phase response, minimal ringing
20EllipticDigitalPrecisionLP/BP/HP/Notch12/24/48/96 dB/octEquiripple passband/stopband, sharp edge
21Vactrol LPGAnalogEmulationLP only12 dB/octLED-driven optical low-pass gate, vintage warmth
22Modal ResonatorAnalogEmulationLP/BP/HP/Notch24 dB/oct8 formant bands, speech-like textures
23Waveguide MeshSVFLP/BP/HP/Notch24 dB/octString synthesis mesh, metallic rings
24Bode Frequency ShifterSpectralLP/BP/HP/NotchN/AHilbert-transform-based frequency shift (±5 kHz)
25Z-Plane 2D MorphSpectralLP/BP/HP/Notch24 dB/oct7-biquad pole-placement morphing
26Phased Array 2SpectralLP/BP/HP/Notch24 dB/octAdvanced all-pass stereo decorrelation
27Nyquist Anti-aliasAnalogEmulationLP/HP12 dB/octTransparent high-frequency limiter

Cutoff Algorithms

Quad Morph Filter provides 3 cutoff calculation modes to suit different workflows:

ModeRangeDescription
Absolute (Abs)20 Hz – 20 kHzDirect frequency position (20 Hz at left, 20 kHz at right)
Relative (Rel)±4 octavesCenter at XY midpoint; ±4 octaves from center
Zone (Zone)AsymmetricDifferent scaling for left/right regions (musical control)

LFO System Guide

19 LFO Waveforms

#NameCategoryDescription
1SineClassicPure sinusoid, smooth modulation
2SawtoothClassicRamp up, bright metallic sweep
3PulseClassicPulse wave, adjustable duty cycle
4TriangleClassicLinear ramp, intermediate brightness
5Random 1RandomStep-wise random jumps
6Random 2RandomSmooth random interpolation
7NoiseRandomWhite noise continuous modulation
8Smooth NoiseRandomHermite-interpolated noise, organic feel
9SpirographGeometricEpitrochoid pattern, spiral curves
10Torus KnotGeometric3D knot unwrap, complex topology
11LissajousGeometric3:2 frequency ratio parametric curve
12SpiralGeometricLogarithmic spiral, organic growth
13StarGeometricRadial star pattern, rhythmic pulses
14RoseGeometricPolar rose curve (Rhodonea), petals
15LemniscateGeometricFigure-8 infinity loop pattern
16BilliardDynamicBall bouncing in a box, collision physics
17PolygonDynamicStep waveform with N-sided geometry
18AttractorDynamicLorenz/Henon chaotic attractor, unpredictable
19RecordingSpecialHand-drawn XY patterns from morph pad

LFO Controls (per LFO)

ParameterRangeDefaultDescription
EnableOn/OffOffActivate LFO modulation
Wave1–19SineWaveform selection
Step ModeOn/OffOffQuantize to steps instead of smooth sweep
SyncOn/OffOnLock to DAW tempo (vs. freeform)
Rate (Sync)8/1 – 1/641/4Tempo-synchronized note divisions
Rate (Free)0.01 – 20.0 Hz1.0 HzFreeform frequency (Hz)
Min0.0 – 1.00.0Lower modulation bound
Max0.0 – 1.01.0Upper modulation bound
Phase0° – 360°0°LFO phase offset
Fade In0 – 10 s0 sFade-in time on plugin load
Spread0° – 360°0°Per-filter phase offset (Spread)

LFO4: Rate Modulation

Modulate the playback rate of LFO1, LFO2, and LFO3 independently:

ParameterRangeDefaultDescription
EnableOn/OffOffActivate LFO4
Wave1–19SineLFO4 waveform
Depth0 – 4.00Rate modulation amount (multiplication factor)
Assign to LFO1/2/3On/OffOnly LFO1Which LFO(s) to modulate

LFO5: Dry/Wet Range Modulation

Control the minimum and maximum mix level of the wet signal via LFO5:

ParameterRangeDefaultDescription
EnableOn/OffOffActivate LFO5
Wave1–19SineLFO5 waveform
Min0 – 100%0%Minimum wet level during LFO cycle
Max0 – 100%100%Maximum wet level during LFO cycle

Parameter Reference

Filter Parameters (per Filter A/B/C/D)

ParameterRangeDefaultDescription
EnableOn/OffA: On / B,C,D: OffActivate filter in morph blend
Model0 – 27A: 0 / B: 1 / C: 3 / D: 14Filter model selection
TypeLP / BP / HP / NotchLPFilter type
Slope12/24/48/96 dB/oct24 dB/octFilter steepness (not all models support all slopes)
Cutoff20 Hz – 20 kHz1000 HzCutoff frequency (log scale)
Res / Ctrl0.1 – 10.00.707Resonance / Emphasis / Feedback

Morph & Blend

ParameterRangeDefaultDescription
Base X0.0 – 1.00.5XY pad X position (left = 0, right = 1)
Base Y0.0 – 1.00.5XY pad Y position (top = 0, bottom = 1)
Morph BlendEqPwr / Linear / Smooth / RadialEqPwrBlending algorithm for 4-filter combination
Cutoff AlgoAbs / Rel / ZoneAbsCutoff frequency calculation mode

LFO Cut/Res Modulation (per Filter)

ParameterRangeDefaultDescription
LFO Cut SrcOff / +X / +Y / -X / -YOffCutoff modulation source from LFO2
LFO Res SrcOff / +X / +Y / -X / -YOffResonance modulation source from LFO3

Master Controls

ParameterRangeDefaultDescription
Output Gain-36 – +24 dB0 dBMaster output level
Dry/Wet0 – 100%100%Wet signal blend ratio
Limit Ceil-36 – 0 dB-0.1 dBOutput limiter ceiling threshold
OS QualityOff / Auto / 2× / 4×AutoOversampling mode (2× for Moog/TB-303)

Global Settings

ParameterRangeDefaultDescription
Envelope Follower EnableOn/OffOffActivate input envelope tracking
Envelope Depth0 – 100%50%Envelope follower modulation amount
Envelope InvertOn/OffOffInvert envelope polarity

Installation

VST3 Plugin Installation

  1. Download the latest QuadMorphFilter.vst3 from the Releases page.
  2. Copy the .vst3 folder to your VST3 plugin directory: 
    C:\Program Files\Common Files\VST3\
  3. Rescan your plugins in Ableton Live (or your DAW of choice).

Standalone Application

A standalone executable is also provided — no DAW installation required. Simply run Quad-Morph Filter.exe directly.

📚 User Guide

Comprehensive user manuals covering detailed operation, advanced techniques, and DSP background are included with this repository.

Manual Markdown (JP)

Manual Markdown (EN)

Build Requirements

  • JUCE 8.0.x — place at C:/JUCE or update the path in CMakeLists.txt
  • CMake 3.24 or higher
  • Visual Studio 2022 (MSVC, C++20)
  • AVX2-capable CPU (required for SIMD optimizations)
  • xsimd 13.0.0 (included in JUCE modules)

System Requirements

  • OS: Windows 10 / Windows 11 (64-bit)
  • Format: VST3 / Standalone
  • CPU: AVX2 support required
  • RAM: 256 MB minimum
  • Disk: 50 MB for plugin + sample assets

⚠️ Compatibility Notice: This plugin is compiled and optimized exclusively for Windows 64-bit with AVX2. Verified operation is confirmed in Ableton Live 11 / 12. Other DAWs (FL Studio, Bitwig, Studio One, Cubase, Reaper, Logic Pro, etc.) may work but are currently unverified. Use at your own risk outside of Ableton Live.

Technical Architecture

Signal Flow Diagram

$ \text{Stereo} \text{Input} (\text{L}/\text{R}) │ ├─► [\text{Dry} \text{Buffer} \text{Cache}] │ ├─► [\text{LFO} \text{Engine} \text{Processing}] ────────────────────┐ │ ├── \text{LFO1} (\text{Morph} \text{modulation}) │ │ ├── \text{LFO2} (\text{Cutoff} \text{modulation}) │ │ ├── \text{LFO3} (\text{Resonance} \text{modulation}) │ │ ├── \text{LFO4} (\text{Rate} \text{modulation}) │ │ └── \text{LFO5} (\text{Dry}/\text{Wet} \text{modulation}) │ │ │ ├─► [\text{XY} \text{Position} \text{Calculation}] │ │ ├── \text{Morph} \text{Blend} \text{Mode}: 4-\text{filter} \text{blend} │ │ └── \text{Cutoff} \text{Mode}: \text{Direct} \text{Cutoff}/\text{Reso} │ │ │ ├─► [\text{Enabled} \text{Filter} \text{Detection}] │ │ └── \text{Count} \text{enabled} \text{filters} (\text{A}/\text{B}/\text{C}/\text{D}) │ │ │ ├─► [\text{Weight} \text{Mix} \text{Calculation}] ◄───────────────────┘ │ ├── \text{if} \text{enabledCount} ≤ 1: \text{constant} \text{weights} │ │ └── \text{if} \text{enabledCount} > 1: \text{morphBlend} \text{algo} │ │ │ ├─► [\text{Per}-\text{Sample} \text{Filter} \text{Update}] │ │ ├── \text{TptFilter} \text{A}: \text{Model} \text{selection} │ │ ├── \text{TptFilter} \text{B}: \text{Cutoff}/\text{Reso} \text{modulation} │ │ ├── \text{TptFilter} \text{C}: \text{Envelope} \text{Follower} (\text{opt}) │ │ └── \text{TptFilter} \text{D}: \text{Oversampling} (2 \times /4 \times ) │ │ │ ├─► [\text{Parallel} \text{Filter} \text{Processing}] │ │ ├── \text{FilterA\_SVF\_SIMD} (\text{AVX2}) │ │ ├── \text{FilterB} (\text{TptFilter} \text{dispatcher}) │ │ ├── \text{FilterC} (\text{TptFilter} \text{dispatcher}) │ │ └── \text{FilterD} (\text{TptFilter} \text{dispatcher}) │ │ │ ├─► [4-\text{Filter} \text{Weighted} \text{Sum}] │ │ └── \text{Output} = \text{wA} \times \text{A} + \text{wB} \times \text{B} + \text{wC} \times \text{C} + \text{wD} \times \text{D} │ │ │ ├─► [\text{Dry}/\text{Wet} \text{Smooth} \text{Crossfade}] │ │ └── \text{Linear} \text{interpolation} (τ = 50 \text{ms}) │ │ │ ├─► [\text{Master} \text{Gain} + \text{Limiter}] │ │ ├── \text{Output} \text{gain} (\text{dB}) │ │ └── \text{RMS}-\text{tracking} \text{brick}-\text{wall} \text{limiter} │ │ │ └─► \text{Stereo} \text{Output} (\text{L}/\text{R}) $

Core DSP Components

ComponentPurpose
LfoEngine19 waveform generation, tempo sync, recording playback
TptFilter28-model dispatcher with per-model coefficient management
FilterA_SVF_SIMDAVX2-optimized Clean SVF (4 parallel, 24dB/oct)
MorphEngine4-way equal-power blend algorithms
FilterVisualizerReal-time 1024-point frequency response display
XYPadComponentMorph control, LFO tab navigation, Recording grid

Real-Time Safety

Quad Morph Filter adheres to the strictest real-time audio constraints:

  • Zero Heap Allocation on Audio Thread: All buffers pre-allocated in prepareToPlay(). No dynamic memory operations in processBlock().
  • Lock-Free Parameter Dispatch: Smart parameter caching prevents unnecessary DSP recalculation.
  • ScopedNoDenormals: Applied at processBlock entry to suppress denormal CPU spikes.
  • SmoothedValue Automation: Gain changes interpolated sample-by-sample to eliminate zipper noise.
  • Safe Timer Management: stopTimer() explicitly called in UI component destructors to prevent DAW cleanup-order crashes.

⚠️ Disclaimer

Software Warranty

This software is provided "as-is", without any warranty of any kind. While extreme care has been taken to ensure real-time safety, audio stability, and Ableton Live compatibility through rigorous testing and professional DSP practices, unexpected behavior may still occur in edge cases or unsupported hosts. Use at your own risk in mission-critical production environments.

🔊 Audio Output & Hearing Protection — Critical Notice

This plugin can generate loud audio output. User bears sole responsibility for safe audio monitoring.

  • HEARING DAMAGE RISK: Prolonged exposure to loud sound (≥85 dB SPL) can cause permanent hearing loss. This risk applies regardless of equipment type or volume settings.

  • SPEAKER / HEADPHONE USE: Always monitor output levels carefully when using speakers or headphones. Start with low volume and gradually increase. Never wear headphones at maximum volume. Take regular breaks during extended use.

  • SELF RESPONSIBILITY: The user assumes complete and exclusive responsibility for:

    • Setting appropriate monitoring levels
    • Protecting their own hearing and that of others
    • Equipment safety and damage risk
    • All consequences of audio output usage

  • NO LIABILITY: The developer(s) and distributor(s) of this software assume no liability for:

    • Hearing loss, tinnitus, or any physical harm
    • Equipment damage due to audio output
    • Any injury or damage caused by improper use

  • USE AT YOUR OWN RISK: By using this plugin, you acknowledge and accept all audio-related risks inherent to audio production software. If you are sensitive to loud sounds or have any hearing condition, consult an audio professional or medical advisor before use.

Your hearing is irreplaceable. Prioritize hearing protection at all times. 🎧

License

This project is licensed under the GNU Affero General Public License v3.0 (AGPLv3) - see the LICENSE file for details. This software is built using the JUCE 8 framework. In accordance with JUCE 8's open-source licensing terms, this entire project is distributed under the AGPLv3.

Credits

Developer: @OTODESK

Music Production Background: Electronic Music, Sound Design, DSP Engineering, JUCE plugin development

Target DAW: Ableton Live 11 / 12

Framework: JUCE 8.0.x

DSP References:

  • Välimäki & Liski — "Accurate Cascade Graphic Equalizer" (2017)
  • Vicanek — "Matched Second Order Digital Filters" (2016)
  • Schattschneider & Zölzer — "New methods for pitch shifting and time stretching" (2014)
  • Schlecht & Habets — "On Lossless Feedback Delay Networks" (2017)
  • Parker et al. — "Modelling plate and spring reverberation using DSP-informed DNN" (2019)

Support

Happy Morphing! 🎵