waver-vst 🎸

VST3 plugin that simulates a double-tracked electric guitar from a single recording.

Takes a mono guitar signal and outputs a processed mono signal — the plugin never mixes the original (dry) audio into its output.

Works in real-time during playback and mixing, and also via Direct Offline Processing in Cubase (F7). Full PDC (Plugin Delay Compensation) support means Cubase automatically keeps the track in time with the rest of the session.

Related: waver — Python CLI version of the same algorithm for batch processing outside the DAW.

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How it works

A real double-track sounds natural because the second take has a slightly different:

• Timing — the guitarist doesn't play in perfect sync
• Pitch — small inconsistencies in fretting and picking angle
• Tone — different mic position, different early room reflections

Waver processes the input into a dedicated processed (wet) signal. It never mixes the original dry audio into the output. The wet path applies the following stages (mono):

1. Granular pitch shift — dual-pointer circular buffer with sin² crossfade, tunable in cents
2. Variable delay — Haas-style base delay plus slow IIR-smoothed random timing drift (no sine LFO → no chorus artefact)
3. EQ tilt — optional high-shelf cut to simulate a different mic/position
4. Internal short IR (FIR) — a small internal impulse applied to the wet path (polarity is flipped before this internal IR)
5. IR convolution (optional) — convolve the wet signal with any external room/mic impulse response

The processor always outputs the wet/processed signal (mono). To create a stereo image in the host, duplicate the track and pan the original and processed tracks left/right.

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Parameters

Double-tracking

Control	Range	Default	Description
Delay	5–40 ms	22 ms	Base Haas delay of the simulated take
Pitch	±25 ct	2.0 ct	Detune of the simulated take in cents
Drift	0–5 ms	0.00 ms	Depth of random timing variation (500 ms smoothing)
Modulation	0–1	0.00	Modulation scale for delay drift
Level	−12–+6 dB	0.0 dB	Level of simulated take relative to original
EQ tilt	on/off	on	−2.5 dB high-shelf cut on wet signal @ 4 kHz

Impulse Response (optional)

Control	Description
Load IR	Load a WAV impulse response file. Applied only to the B track (simulated take).
IR enabled	Toggle IR convolution on/off without unloading the file
IR mix	0–100 % blend between dry and convolved B track

Tip: Short room IRs (20–80 ms) or mic scatter IRs (< 10 ms) work best. The IR is normalised on load so it won't spike the level on hot recordings. The loaded IR path is saved in the Cubase project and reloads automatically.

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Workflow in Cubase

Option A — Real-time insert (playback & mixing)

1. Record guitar on a mono audio track
2. Duplicate the track (Edit → Duplicate Track)
3. On the duplicate track, insert Waver as a stereo insert effect
4. Pan the original track hard L, the processed track hard R
5. Done ✅ — Cubase PDC keeps everything in sync automatically

Option B — Direct Offline Processing (renders to audio)

1. Record guitar on a mono audio track
2. Duplicate the track (Edit → Duplicate Track)
3. Select the audio clip on the duplicate → open Direct Offline Processing (F7)
4. Add Waver → Apply
5. Pan the original track hard L, the processed track hard R
6. Done ✅

The plugin is mono-in / mono-out. It outputs only processed (wet) audio and never mixes the original dry signal. To create a stereo image, duplicate the track and pan original/processed left and right in your DAW.

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Cubase compatibility notes

• PDC — latency is reported to Cubase (PitchShifter::kBufSize / 2 ≈ 186 ms at 44.1 kHz); Cubase compensates automatically so the track stays in sync
• Tail flush — getTailLengthSeconds() is implemented so Cubase flushes the delay buffer at the end of a clip
• Transport reset — reset() clears all ring buffers on loop restart or transport stop; no artefacts on punch in/out
• Project state — all parameters and the IR file path are saved in the Cubase project XML and restored on reload

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Distorted and hot recordings

• Works on pre-distorted signals (DI through pedals/amp sim, or recorded from a mic'd cab)
• Output stage applies a tanh soft clipper — starts acting around −6 dBFS, no hard clipping, transparent on normal levels, graceful saturation on overshoots
• IR is normalised on load — high-energy room IRs won't cause level spikes
• For best pitch-shift quality on heavily distorted signals, keep Pitch ≤ 8 cents

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Download

Pre-built Windows x64 VST3 binaries are available on the Releases page. A Cubase sample project for quickly testing Waver is available at https://github.com/gurrish/waver-sample-project — download it and open the project in Cubase to test the plugin.

1. Download Waver-windows-x64.zip
2. Extract Waver.vst3 to C:\Program Files\Common Files\VST3\
3. Rescan plugins in Cubase (Studio → VST Plug-in Manager → Rescan)

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Building from source

Prerequisites

• Visual Studio 2022 or later (Community / Professional / Enterprise)
• CMake ≥ 3.22

Steps

git clone --recurse-submodules https://github.com/gurrish/waver-vst
cd waver-vst
cmake -B build -G "Visual Studio 17 2022" -A x64
cmake --build build --config Release

The compiled Waver.vst3 is output to build/WaverVST_artefacts/Release/VST3/.

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DSP architecture

Stage	Algorithm
Pitch shift	Dual-pointer granular, sin² crossfade, 16384-sample buffer
Timing drift	IIR-smoothed LCG random walk, 500 ms time constant (cubic interpolation in delay reads)
Internal short IR	Small FIR-style impulse applied to wet path; polarity is flipped before this stage
IR convolution	juce::dsp::Convolution, normalised, async load (optional external IR)
EQ	Single high-shelf biquad on wet signal
Output	tanh soft clipper (drive 1.5×, unity-gain preserving); plugin outputs processed mono only

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Project structure

waver-vst/
├── CMakeLists.txt
├── JUCE/                              ← git submodule
└── Source/
    ├── PluginProcessor.h / .cpp       ← AudioProcessor, APVTS, convolution, state
    ├── PluginEditor.h  / .cpp         ← GUI (4 knobs + 2 toggles + IR section)
    └── DSP/
        ├── PitchShifter.h / .cpp      ← Granular dual-pointer pitch shift
        └── VariableDelay.h / .cpp     ← IIR-smoothed variable fractional delay (cubic interpolation)

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License

This project is licensed under the GNU General Public License v3.0 — see LICENSE for details.

This is required because the project is built on JUCE, which is GPL v3 for open source use. If you want to use this code in a proprietary (closed-source) product, you must obtain a commercial JUCE license from Raw Material Software Limited.