idlefoundry / ca-72

# CA-72
A synthesizer for macOS, Windows and Linux, as a standalone application, VST3 and CLAP
plug-in, and an Audio Unit for macOS, by Idle Foundry:
monophonic like the instrument it models, or one whole instrument per note with POLY. Its
voice is modelled from the circuit of a 1970s analogue synthesizer, the
Minimoog Model D of about 1972-73 with the CA3046 ("old") oscillator board. Every board
was transcribed from the instrument's service documents into SPICE netlists and simulated
in ngspice. The real-time models were then derived from those simulations and tested
against them, the factory calibration procedures included.
Hear it before you download: the CA-72 on YouTube.
It is free software under the GNU General Public License, version 3 or later. Copyright ©
2026 Idle Foundry Ltd.
**Status:** 0.2.6: same sound, lighter on your computer: output bit-identical to 0.2.5, HI up to
17 % lighter on a Mac and 9 % on Windows and Linux, smoother with several instances, and a panel
that rests while you can't see it. Includes 0.2.5: a new instance starts at QUALITY LO, the light voices (projects keep their
own; 0.1's open at HI), and on macOS the pointer shows resize arrows over the grip. Includes
0.2.4: LETTERING › LARGE in the settings menu prints the panel's lettering and
the menus a size larger, and WINDOW › SIZE… sets the window's size; the resize grip can be
seen. Includes 0.2.3: a standalone application with audio and MIDI selection, a playable lower
keyboard, and independent computer-keyboard octaves. Includes 0.2.2: PANEL shows or hides the
lower controls; strong filter contours
in HI and LO keep ultrasonic resonance out of the output. Both modes use more CPU and their
renders change; ULTRA is unchanged. Includes 0.2.0: the circuit calibrated against a hardware instrument, projects saved with
0.1 translated into it; nineteen new factory presets, 0.1's in a download of their own; the
realistic look; QUALITY's LO, HI and ULTRA; stereo with SPREAD, INNER, DOUBLE and UNISON;
DRIVE, LEVEL and AUTO GAIN; FILTER MODE; NOTE PRIORITY and RETRIGGER; and an instance waiting
costs next to nothing. The macOS installer is signed and notarised; the Windows one is not yet
signed.
## Installing
1. Download the installer for your computer from the
 latest release:
 | Computer | Download |
 |---|---|
 | macOS 11 or later, Apple silicon or Intel | `CA-72- -macOS.pkg` |
 | Windows 10 or 11, 64-bit | `CA-72- -Windows-setup.exe` |
 | Linux, x86-64 (Ubuntu 22.04, Debian 12, Fedora 36 or later, or Arch) | `CA-72- -Linux-x86_64.tar.gz` |
2. Run it. On Linux, unpack it and run the script in its folder:
 [code] 
3. In your host, rescan the plug-ins or restart it. The CA-72 appears as an instrument by
 Idle Foundry, in VST3 and CLAP, and on macOS as an Audio Unit too (in Logic Pro and
 GarageBand, under **AU Instruments › Idle Foundry**). The macOS installer has the Audio
 Unit from 0.1.2 on.
The Windows installer is not yet signed, so the first time you run it Windows sa