RE-DEEMER — Cassette Tape Echo

A software realization of a cassette tape echo instrument that was announced around 2018, pre-ordered by many, and never shipped. The preorder, redeemed: free, for everyone who waited.

Website & download · Latest release · Manual · Changelog

Formats: VST3 · CLAP · AUv2 (via clap-wrapper). macOS universal (signed & notarized), Windows and Linux (CI-built each release). Built in Rust on nice-plug.

What's inside

The tape is real, not a delay line: a position-indexed tape buffer at a fixed 96 kHz tape rate with fixed record/repro heads and a motor model. TIME is motor speed — turning it repitches everything already on tape; MTR drags the pitch to a dead stop; RW/FF shuttle the actual tape; the cassette-synth and PLAY-mode manipulation fall out of the same physics.

• Magnetics: Jiles–Atherton hysteresis (Chowdhury, DAFx-19) solved with RK4 at 2×/4×/8× oversampling; bias blends the anhysteretic (ideally biased) path against the raw hysteresis loop. Tape types I/II/IV change saturation, EQ, self-erasure and hiss.
• Tape stock & aging: fourteen real-world cassettes in three grades set hiss, headroom and wear rate; the tape audibly ages while the transport rolls (wear is saved with the project, and eject loads a fresh one). The spools in the window move on real tape footage over a 30-minute side.
• Heads & EQ: record pre-emphasis (HF saturates first), de-emphasis, speed-tracking head bump and gap loss, spacing loss, level-dependent HF self-erasure.
• Mechanism: always-on wow/flutter/scrape calibrated to ~0.15% RMS, dropouts and bias sag scaling with the MECH control; tape noise is recorded onto the tape so it regenerates through the feedback loop.
• Filters: 24 dB/oct OTA ladder HPF + LPF (ZDF), resonance to clean self-oscillation with pitch tracking; the RES gate turns the 1–8 buttons into an 8-pitch filter keyboard (MIDI C3–G3, enabled in SETUP).
• Positions & Sets: 3 sets × 8 positions (21 faders), per-set DRIFT slew 0–14 s, Cycle from 8 s/step to 4,000 steps/s with a sample-accurate clock, host-tempo sync phase-locked to the playhead. Anomaly fires a motor hiccup on the cycle's final step.
• Transport: REC/ECHO, PLAY, LOOP (erase bypass = sound-on-sound layering), RW/FF, PAUSE, STP/EJ (double-press ejects to a fresh cassette).

Building

rustup default stable          # 1.87+
cargo xtask bundle te2-plugin --release            # VST3 + CLAP
cargo xtask bundle-universal te2-plugin --release  # macOS universal

Run from the repo root (the xtask alias only resolves there). Bundles land in target/bundled/. Install:

• RE-DEEMER.vst3 → ~/Library/Audio/Plug-Ins/VST3/
• RE-DEEMER.clap → ~/Library/Audio/Plug-Ins/CLAP/

AUv2

The AU is a clap-wrapper component that loads the installed CLAP, so install the CLAP first.

cmake -B wrapper-au/build -S wrapper-au -DCMAKE_BUILD_TYPE=Release
cmake --build wrapper-au/build
cp -r wrapper-au/build/RE-DEEMER.component ~/Library/Audio/Plug-Ins/Components/
auval -v aumf Rdmr Ntrm

Or run ./scripts/package.sh, which does all of the above plus tests and produces the distribution zip. scripts/notarize.sh signs/notarizes a release (needs a Developer ID; see README-RELEASING.md).

Dev tools

cargo test --workspace --release       # DSP test suite: timing, repitch, W&F,
                                       # magnetics, sequencer, aging, transport
cargo run -p te2-render --release -- gen pluck /tmp/p.wav
cargo run -p te2-render --release -- render /tmp/p.wav /tmp/echo.wav \
    --time 0.4 --feedback 0.8 --lpf 2500 --tail 6
cargo run -p te2-plugin --release --features standalone --bin te2-standalone
cargo run -p te2-plugin --release --features snapshot --bin te2-snapshot out.png

Validation status

Check	Result
clap-validator 0.3.2	all run, 0 failed
pluginval 1.0.4, strictness 10 (VST3)	SUCCESS
auval (aumf Rdmr Ntrm)	PASS
te2-dsp test suite	47/47
Engine CPU (48 kHz stereo, 4× OS)	~13× realtime on one Apple-silicon core

Notes

• License: ISC. vendor/baseview is a patched fork of baseview (MIT/Apache-2.0) fixing a host-KVO recursion crash; see the patch comments.
• The vst3 bindings are MIT/Apache-2.0, but distributing VST3 binaries involves Steinberg's VST3 licensing terms (or GPLv3). CLAP and AU carry no such strings.
• Windows and Linux builds come from CI (.github/workflows/ plugins-portable.yml) and pass clap-validator there; they're younger than the macOS builds — reports welcome.
• Save your own presets in SETUP → PRESETS (stored in your user config folder); PRESETS.md has 16 starter panel recipes; ROADMAP.md is what's next.

A tribute. You waited long enough.