CA-72
Key Features
- Circuit-derived instrument modeling is based on the CA3046 oscillator board used in early Minimoog Model D revisions.
- Monophonic lowest-note-priority operation preserves the original performance-oriented synth behavior.
- POLY assigns a full synth voice to each note, with a selectable range of two to ten voices.
- ENTROPY adds component variation, oscillator and cutoff drift, and subtle voice-to-voice differences.
- SPREAD places polyphonic voices across the stereo field for wider pads and chord parts.
- Feedback and external-input controls recreate a hardware-style route for driving the modeled preamp and mixer.
- Twenty-four factory presets include conventional synth sounds plus drum-kit and riser examples.
Description
CA-72 is an open-source virtual instrument from Idle Foundry that models the oscillator-board circuitry of an early-1970s Minimoog Model D. It keeps the focused three-oscillator, ladder-filter character of that design while supplying VST3 and CLAP builds for macOS, Windows, and Linux.
The instrument can run as a traditional lowest-note-priority monosynth or switch to POLY, where each played note receives a complete synth voice. POLY supports two to ten voices, turning a classic bass-and-lead architecture into a tool for chords, pads, and layered electronic parts.
ENTROPY introduces per-voice component variation, slow drift, and tuning differences, while SPREAD positions polyphonic voices across the stereo field. A feedback path recreates the original hardware trick of routing the phones output into the external-input circuit for driven preamp and mixer color.
Version 0.1.0 includes 24 factory presets, including drum and riser sounds alongside polyphonic pads. The developer supplies a signed and notarised macOS installer, Windows and Linux builds, and public source code under GPLv3-or-later; Windows users should note that the current installer is unsigned.
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Frequently Asked Questions
What is CA-72 modeled on?
CA-72 models circuitry from an early-1970s Minimoog Model D, specifically the CA3046-based oscillator board used in the older revision. Idle Foundry says it transcribed the relevant boards into SPICE netlists before deriving the real-time models.
Can CA-72 play chords?
Yes. With POLY enabled, CA-72 gives each note a complete instrument voice and supports two to ten voices. With POLY off, it follows the modeled instrument's lowest-note-priority monophonic behavior.
What do ENTROPY and SPREAD do?
ENTROPY introduces small per-voice differences and slow drift in oscillator tuning, filter cutoff, contours, and glide. SPREAD distributes POLY voices across the stereo field; it is inactive while POLY is off.
Which formats and systems are supported?
The official release provides VST3 and CLAP versions for macOS, Windows, and Linux. Idle Foundry lists macOS 11 or later on Apple Silicon or Intel, Windows 10 or 11 64-bit, and x86-64 Linux for Ubuntu 22.04, Debian 12, Fedora 36, or later.
Is the Windows installer signed?
Not yet. The developer states that the macOS installer is signed and notarised, while the current Windows installer is unsigned and may show the Windows protected-PC warning on first launch.
