CA-72 0.3.0

An arpeggiator, effects and AI agents in the standalone, skin packs, and cleaner high notes.

Install

Close your host, run the installer (it installs over earlier versions), then rescan your host's plug-ins. The standalone application is an optional installer component; on Linux, --standalone-only and --plugins-only select what to install. The Windows installer is not yet signed: when Windows says "Windows protected your PC", click More info, then Run anyway.

SHA256SUMS.txt lists checksums for the installers, Windows ZIP, retired presets and sources archive. THIRD-PARTY-NOTICES.txt contains third-party licences; CA-72-0.3.0-git-sources.tar.gz contains the git-pinned dependency sources. The CA-72's own source is this repository at v0.3.0.

In this release

New

• Final owner edits to Cycle of Fifths and Hold Me Long Time. Factory sounds contain no hosted VST3 or CLAP effects.

• Twenty-three new factory presets, forty-two in all. Sounds the set lacked: an organ
  (Tonewheel Drift), a glass bell, acid and sub basses (Acid Squelch, Deep Boom), a plucked chord
  stab (Zither Me Timbres), a tom (Pitch Tom), a ray gun, waves of pink noise (Night Surf) and a
  dark drone (Droning On). Arpeggios in time with your host, or the standalone's TEMPO (Octave
  Runner, Random Glass, Swing Keys); a wobble, a gate and a bubbling sequence locked to the
  tempo (Tempo Wobble, Gatekeeper, Bubble Computer); strings and a pad on
  CONTINUOUS waveforms (Pulse Strings, Morph Bloom); Pressure Solo, a lead for MPE or aftertouch;
  four presets whose LFOs move each other (Finger in a Light Socket, Phase Chase, Level Pump,
  Hold Me Long Time); and Velocihator, a hi-hat that follows how hard you play, as Zither Me
  Timbres does. Most have named macros to turn. Each plays at the set's loudness. Find them by the
  tags arp, lfo, loop, macros, tempo or expressive. Two older presets are new versions: Bright
  Xylo runs on the arpeggiator, and Feedback Funk is brighter with less FEEDBACK. Three more are
  levelled again to match the set: Driven Kick 7.8 dB quieter, Smoke Flute 2.7 dB louder and
  Swarm Riser 2.2 dB quieter.

• GLOBAL on the rail. GLOBAL, KEYS and LFO select the three lower pages; GLOBAL holds VOICES, STEREO and OUTPUT. The selected key stays lit, and any page key shows the lower panel if hidden. PANEL still shows or hides it.

• GLIDE goes five times longer: right-click it and choose LONG. A small ×5 beside its dial shows the range; saved with presets and projects.

• An arpeggiator. Press ARP on the rail (after LFO) and a drawer drops down
  over the lower panel with the arpeggiator's controls: ON and HOLD, DIRECTION (UP,
  DOWN, UP/DOWN, RANDOM, ORDER), RATE (a half note to a thirty-second, with dotted and triplet
  values), OCTAVES (1 to 5), GATE and SWING. It plays the keys you hold in turn, in
  time with your host: locked to its bars while the transport plays, at its tempo while it is
  stopped. Its notes go through the instrument just as played ones do, so MONO, POLY, UNISON,
  NOTE PRIORITY, RETRIGGER and GLIDE all work with it. Every setting can be automated and is
  saved with presets and projects. In the VST3, CLAP and Audio Unit plug-ins and the standalone
  application.

  • ORDER plays the keys in the order you pressed them; a key you add goes on the end.
  • OCTAVES repeats the pattern up to five octaves; a note that would go past the top of the
    range plays in the highest octave it has, so no step falls silent.
  • GATE is each note's length within what the instrument can play: even at 0 % and at the
    fastest rates every note sounds, and each starts its contours again.

• Drones with HOLD. With the arpeggiator off, HOLD keeps the notes you play sounding
  after you let go, as you played them, until you play a new chord or switch HOLD off.

• Timed oscillators. Oscillators 2 and 3 each have a small key under their RANGE. At
  LO, press it and the oscillator's cycle becomes a note value of your host's tempo, from four
  bars to a thirty-second (with dotted and triplet values), locked to the song position so it
  never drifts. Its FREQUENCY dial turns into note values while it is timed (4× 2× 1 2 4 8 16 32),
  and the note beside the key shows the one chosen. Oscillator 3 timed makes a tempo-synced LFO
  through MODULATION MIX. FREQUENCY keeps its own setting for when the key is off; at another
  RANGE the key leaves the panel. Saved with presets and projects; old ones open with
  it off.

• A continuous waveform, and shape modulation. Right-click any oscillator's WAVEFORM switch
  and choose CONTINUOUS under WAVEFORM. The switch then turns without steps through every
  shape, each blending into the next (triangle, shark tooth, sawtooth, square), and on through
  WIDE and NARROW to a narrow pulse of about 6 %. On oscillator 3 the path runs triangle,
  reverse shark tooth, reverse sawtooth, then the square and pulses. A thin arc printed round the
  switch shows it is CONTINUOUS, and its tip names the shape. Dragging turns it in one smooth motion;
  click a legend to land exactly on the original instrument's shape.
  A MOD key appears under the switch: press it and the shape follows the modulation
  (MODULATION MIX's blend of oscillator 3 and the noise, as deep as the MODULATION wheel is
  forward), which makes pulse width modulation in the rectangle's stretch and waveform morphing
  everywhere else. Command-click the key (Ctrl-click on Windows and Linux) to change which way
  it moves the shape: clockwise (amber), anticlockwise (blue) or both ways about the switch
  (red). A small orb of the same colour on the switch's ring shows where the shape is as it
  moves. STEPPED, the default, is the instrument's switch, and CONTINUOUS at a legend is
  that switch's shape to the bit. Saved with
  presets and projects; old ones open STEPPED.

• The standalone's tempo on the panel. A screen at the top left shows the tempo the
  arpeggiator follows in the standalone application. Drag it, scroll it, or double-click it and
  type a tempo (30 to 300 BPM, 120 by default); it is also in Audio & MIDI. In a plug-in, the
  host sets the tempo.

• Effects in the standalone application. Press FX on its rail (after ARP) and a drawer
  drops down with four slots for your own CLAP and VST3 effects, run after the synthesizer in the
  order shown. + ADD EFFECT lists the effects on your computer (found the first time you open
  it); click an effect's name to open its window, its ON tab to switch it on and off, drag a
  name onto another slot to reorder, and right-click for REPLACE… and REMOVE. Each effect
  runs in a process of its own: one that crashes is started again, and one that keeps crashing is
  switched off and marked on its slot, while the synthesizer plays on. The chain and each effect's
  settings are kept with the standalone's session. The plug-ins' rail is unchanged.

• Pinned effect parameters. Each loaded effect has one label strip: + PIN opens its
  searchable parameters, or touch a control in the effect's window and click its offered name.
  The offer's arrow opens the list with JUST TOUCHED first. Click a pinned name to replace
  its parameter while keeping its LFOs, macros and MIDI Learn. Pin up to four knobs per slot. Drag LFO or macro cords to them, edit depths from
  their rings and pop-up, or use each pin's MIDI LEARN. Values use the effect's own text;
  unavailable effects keep their pins and assignments, dimmed and inert.

• Effects in standalone presets. Presets save the chain you hear. Unlocked, choosing one
  replaces the chain (a factory or older preset clears it). CHAIN › LOCK keeps your effects
  while you browse and stays set between launches; a dim padlock shows on FX. A dim FX
  by the preset's name and dim names under the slots show a different chain held beneath the
  lock. Unlock to load it. Saving while locked saves what you hear. Plug-in instances ignore
  the effects and keep their saved section when re-saving a preset. Pinned parameters and
  their LFO and macro assignments travel with the chain.

• Find an effect. The FX chooser searches names, makers and types as you type, groups by
  MAKER or TYPE, and keeps the last six effects chosen under RECENT across launches.
  Up and Down mark a row, Enter chooses it, and Escape clears FIND before closing the list.

• No effect can stop the standalone starting. It opens and plays at once while your effects
  load. An effect that crashes or stops responding is switched off and stays off the next time
  (CRASHED or NOT RESPONDING on its slot) until you click it to try again; if its saved
  settings are what crash it, right-click for LOAD WITHOUT ITS SETTINGS (they are kept). If
  the standalone did not close properly last time, or you hold Shift (Option on a Mac) as it
  opens, it starts with the effects off: click a slot to turn them back on.

• Fit presets to audio references with an agent. The MCP bridge renders candidates
  offline through the synth's normal processing, analyses local WAVs, and compares pitch,
  harmonics, modulation sidebands, envelopes and spectrograms. Comparisons provide level-matched
  A/B audio. The reference-matching prompt guides the agent through fitting, saving and
  reloading a preset, including file export/reload without an open app. Rendering uses the dry synth, with repeatable settings and seeds; hosted
  effects and live controller state are excluded. The bridge is included with the application.

• AI agents can play and set up the standalone application through the Model Context
  Protocol (MCP). Switch on SETTINGS › AGENTS › ALLOW (off by default; the standalone only)
  and an MCP client such as Claude can read and set the panel, choose and save presets, change
  settings, play notes and assign MIDI Learn, in the panel's own units, through the bundled
  ca72-mcp bridge, on macOS, Windows and Linux. COPY SETUP: CLAUDE CODE (or JSON FOR
  OTHER APPS) under AGENTS puts the setup, with the bridge's path, on your clipboard, and the
  line under ALLOW says whether agents are connected. The connection is local to your computer
  and your user account; an agent can switch agents off but never on. docs/mcp.md lists the
  tools.

• Each note's own expression (MPE). With an MPE controller, each note's pressure, timbre
  and pitch bend move only that note's voice; polyphonic aftertouch and CLAP and VST3 note
  expressions do too, and ordinary channel pressure and CC 74 move every voice alike. Press
  EXP on the rail (after ARP) for a drawer that shows what comes in (INPUT: MPE,
  CHANNEL or dark) and sets how far PRESSURE and TIMBRE move each voice's
  MODULATION (-100 to 100 %) and filter CUTOFF (-4 to 4 octaves). All four start at 0,
  so presets and projects sound as before; the key glows while any is turned. In Settings,
  MPE › INPUT & TIMBRE… chooses for this computer where the zone comes from (AUTO, LOWER
  ZONE for hosts that drop the controller's configuration, or OFF) and where timbre rests
  (CENTERED ON 64 by default, FROM 0, or FROM THE NOTE'S START).

• Four LFOs. Press LFO on the rail (after KEYS) for a page of four LFOs
  in the keyboard's place, each with an oscilloscope in its own colour showing its waveform and
  an orb where it is now, MODE (FREE, RETRIG, ENV), MONO, WAVEFORM (stepped or continuous, and
  REVERSE in its menu), RATE (0.01 to 50 Hz, or a note value of your host's tempo), PHASE and
  FADE, an ON key at its title to mute it, and a UNI key to make it move its knobs one way. Drag a cord from an
  LFO's OUT jack to any of the panel's continuous knobs to modulate it (25 % to start, up to
  eight knobs an LFO); the knob shows a ring in the LFO's colour, and its pop-up, its ring's end,
  Alt/Option-drag and its right-click menu set the depth. The strip's knobs take an LFO from
  their menu. Right-click a scope for its colour and its EDGES. Presets and projects saved
  before have none assigned and sound as they did.

• FADE, in or out. Each LFO's FADE knob is off at its centre, where it settles when you let
  it go near it. Turn it right and the LFO fades in after each note, as a delayed vibrato does;
  turn it left and the LFO starts at full and fades out, for a wobble that settles. Up to 10 s
  either way, with fine control of short fades near the centre; type a value at it
  (Command-click, or Ctrl-click on Windows and Linux) in seconds, negative for a fade out. It restarts as RETRIG and the
  RETRIGGER switch say, and an LFO or a macro can move it, across the centre too. Presets and
  projects from the 0.3.0 beta that used RISE open with the same fade in.

• LFOs that move LFOs. The LFO page's own knobs take cords too: drag from any LFO's OUT jack
  (its own included) or a macro's jack to an LFO's RATE, PHASE, FADE or (CONTINUOUS) WAVEFORM,
  or to an LFO's OUT jack to move its LEVEL, how much of every assignment it gives (a new
  host parameter, 100 % to start; turn it with the wheel over the jack). Loops are allowed: two
  LFOs speeding each other up, or one on its own RATE, evolve without ever running away, and play
  the same at every sample rate and buffer size, live and when you export. Four factory presets
  show them off: Finger in a Light Socket, Phase Chase, Level Pump and Hold Me Long Time.

• LFOs and macros move the tempo (standalone). Drag a cord to the standalone's TEMPO screen:
  the arpeggiator, the timed oscillators and LFOs, and your effects follow the moving tempo
  smoothly, never jumping, and the screen shows it. Rails under the screen show each source's
  swing; right-click the screen for DEPTH… and REMOVE. The plug-ins follow your host's tempo, so
  there a patch keeps such an assignment without using it.

• Screens show what you hear. A screen whose control an LFO or a macro moves (DRIVE, WIDTH,
  ENTROPY, DETUNE, INNER, LEVEL, AUTO GAIN, TEMPO) shows the value as it plays, and its own value
  while you turn it; an LFO scope whose shape, PHASE or LEVEL another source moves draws the
  waveform as it plays now.

• Six macros. Press MACRO at the rail's far left and the wheels' place under it shows six
  macro knobs, each with a name you type on its dot screen (double-click it) and a jack. Drag a
  cord from a macro's jack to a knob, as from an LFO's: the macro moves it one way, from where you
  set it toward its depth as you turn the macro up, so one macro can open the filter, add drive
  and slow the attack together. The macros are host parameters, MACRO 1 to MACRO 6, for
  automation and MIDI Learn; their names and what they move are saved with presets and projects.
  Right-click a macro's name for its colour. The wheels and their switches keep working while the
  macros show; press MACRO again for them.

• Velocity moves knobs. A VELOCITY jack sits in the left hand under GLIDE and DECAY, with
  a meter beside it that lights to each note while velocity moves something. Drag a cord from it
  to a knob, as from an LFO's OUT jack (25 % to start, up to eight knobs): each voice takes its
  own note's velocity, so the harder notes of a chord open further, and in MONO a legato note
  takes its new velocity smoothly. The expression drawer's second row shapes it: CURVE (SOFT
  to HARD), FLOOR (the least a soft note gives), a RESPONSE screen drawing the curve with
  your last note on it, LAST NOTE (0 to 127) and MODULATES. The on-screen keyboard plays
  softer near the top of a key and harder near its foot. Presets and projects saved before have
  nothing assigned and sound as they did.

• See what a jack moves. Point at an LFO's OUT jack, a macro's jack or VELOCITY and cords show
  to every knob it moves, each knob ringed in the source's colour. Settings › HOVER CABLES
  turns them off.

• The rail's keys show what affects the sound. ARP, EXP, LFO, MACRO and the standalone's FX
  are lit while their page, drawer or macros show and glow faintly while what they open is
  changing the sound with it closed.

• Change presets from your keyboard or MIDI pads. With the editor focused, the Left and
  Right arrow keys choose the previous and next preset, like the ‹ › keys beside the preset's
  name. Text fields, the open preset list, menus and dialogs keep their keys; TYPING leaves the
  arrows available. Right-click either preset arrow and choose MIDI LEARN to assign a note or CC
  pad. Each press changes one preset, with no repeat while held, in the standalone and plug-ins,
  even with the editor closed. These two assignments stay on this computer, outside sound
  presets and projects.

• Map MIDI controls by clicking them (standalone). Press MIDI on the walnut, between
  TYPING and PANIC. Every control MIDI Learn can learn is outlined, with its controller in small print
  (CC 74). Click a control, then move a knob, fader or button on your controller: it's
  assigned, and the mode stays on for the next control, as in Ableton Live's or Bitwig's mapping
  modes. A switch waiting takes a note as well; that note then turns it on and off and doesn't
  play. Delete removes the chosen control's controller; Escape stops waiting, then leaves the
  mode. The rail's keys still work, so you can map the GLOBAL, LFO and MACRO pages and the ARP,
  MPE and FX drawers too. In plug-ins, right-click a control and choose MIDI LEARN as before.

• Choose what moves the MOD wheel. In Settings, choose MOD WHEEL SOURCE: the usual CC 1,
  breath (CC 2), foot (CC 4), expression (CC 11), timbre (CC 74), another available CC, channel
  aftertouch, or the strongest polyphonic aftertouch of the notes you hold. You can also
  right-click the panel's MOD wheel and choose MIDI LEARN, then move your controller. The source
  follows any MIDI channel and stays on this computer, outside sound presets and projects.

• Type a value at any knob. ⌘-click on a Mac, or Ctrl-click on Windows and Linux, opens a
  value field at a panel or strip knob, RANGE selector or WAVEFORM selector. Type a value in its
  displayed units and press Enter; Escape or a click elsewhere cancels. Each confirmed change is
  one host automation gesture. On the arpeggiator's and the MPE drawer's knobs it types into
  the drawer's readout.

• Skin packs. The editor's looks are now packs in one open format: pictures, drawings,
  fonts and a layout, never code. A pack can dress the panel, the strip, the keyboard view and
  the presets' drawer and move the panel's controls; a missing, damaged or incompatible pack
  falls back to the standard look, and nothing about the sound depends on one.
  docs/skin-packs.md describes the format.

Sound

• Cleaner high notes in every QUALITY mode. The oscillators are band-limited far more
  thoroughly, so the bright, inharmonic aliasing of high notes is gone: on a saw at A4 it falls
  from about −39 dB to −112 dB in LO and HI, and from −78 dB to −126 dB in ULTRA. The top
  octave of HI and LO is no longer about 3 dB dull. ULTRA is now as clean at 44.1 kHz as at
  48 kHz.
• ULTRA's VCA runs at four times the sample rate, which removes the aliasing it added to
  bright and driven sounds (an open saw at A4: from −45.5 to −70 dB). ULTRA takes about seven
  times the work of HI.
• One latency in every QUALITY mode. The CA-72 reports the same small latency (86 samples,
  about 1.8 ms at 48 kHz) in LO, HI and ULTRA, so switching QUALITY never shifts your timing.
  The envelopes now meet the sound they shape, as in the circuit; before, they opened up to
  1.4 ms early.

These change how existing projects render, slightly: levels stay within 0.11 dB, but fast
attacks that meet a fast sweep of pitch or cutoff sound a little different. Presets and projects
open with the arpeggiator and HOLD off.

• Waveforms and noise closer to the instrument. The oscillators' triangle and rectangles
  are calibrated, through the circuit's simulation, against recordings of a hardware reference:
  on its oscillator 1, the triangle's harmonics now stand within 1.5 dB of the reference's (4.0
  dB before), and the square's and rectangles' within 1 to 2 dB (8.6 to 9.7 dB before). The
  waveform switch's resistor divider, which the model had left out, now sets the rectangles'
  widths, as in the circuit: WIDE RECTANGLE reads 29 % (30 % before). The sawtooth is unchanged.
  The pink noise is brighter above 2 kHz, by up to 3 dB, as the reference's is.
• FEEDBACK in ULTRA, as the hardware's. The loop from the output back into EXTERNAL INPUT
  now runs at the filter's rate. It no longer rings near 500 Hz at high EXT. INPUT VOLUME, and it
  fills out the low end where it used to add top. At EXT. INPUT VOLUME 10 the loop's own
  oscillation now runs at the reference's pitch, in HI as in ULTRA. ULTRA plays such patches
  about 17 % faster.
• Filter sweeps start where the circuit's rest. With a long DECAY (past about 6), a voice's
  first filter sweep began up to an octave low at AMOUNT OF CONTOUR 10. It now starts where the
  circuit's does.
• LO follows HI more closely. LO's filter now sings on its own at full EMPHASIS with every
  source off (it was silent), and its filter contour works as the circuit's: through a slow sweep
  at EMPHASIS 10, LO stays within about half a semitone of HI, where it fell 2 to 3 semitones
  flat.

The calibration changes how existing projects and presets sound, mostly slightly. Played the
same before and after, the factory presets' levels stay within 0.15 dB at HI and ULTRA, and
every third-octave band within about 1 dB. The exception is Feedback Funk in ULTRA, whose
FEEDBACK loop is now the hardware's: 2.2 dB quieter, up to 10 dB fuller from 100 to 250 Hz and
9 to 15 dB darker above 2 kHz. At LO, levels stay within 0.2 dB (Feedback Funk 0.4 dB quieter
on its own phrase) and bands within 2.4 dB, except Smoke Flute's faint 3.2 kHz band, 6 dB lower,
and Feedback Funk's top, up to 2.7 dB less from 5 to 10 kHz. Patches built on the triangle, the
rectangles or pink noise change the most. Presets keep their knobs and their levels, but for
the two remade and the three levelled again (see the new presets above); their AUTO GAIN curves are measured again (within 0.06 dB at each
preset's DRIVE). Projects keep the AUTO GAIN
curve saved with them.

Performance

• QUALITY LO uses spare processor cores. LO now shares its voices with the worker threads
  HI already uses, which takes half to three quarters of its work off your host's audio thread.
  On a Mac and on Linux it always does; on Windows it does when the computer is busy (after a
  single late block), and otherwise plays as before. The sound is the same to the bit.

Fixed

• Modulation-depth pop-ups disappear as soon as you press a main control, and stay out of the way while you drag it.

• An agent client that stops reading replies no longer prevents the standalone from closing or AGENTS from being switched off.

• The drawers' digits now match GLOBAL's size, and their printed legends and titles match the panel in both looks, with LARGE lettering too.

• Knobs, smooth from the mouse, a trackpad and automation: turning a knob by dragging or
  scrolling, or automating it in your host, changed the sound in small audible steps, most
  plainly on CUTOFF with EMPHASIS high. Knobs now move smoothly, in offline renders too, while
  choosing a preset still changes the sound at once. Continuous knobs also follow every fraction
  of a drag or a trackpad's scroll, instead of waiting for a whole scroll notch or the first
  three pixels of a drag; a mouse wheel still turns a knob a notch at a time. RANGE, WAVEFORM,
  VOICES, the arpeggiator's RATE and OCTAVES and other stepped controls still step.

• Fewer dropouts with DOUBLE at HI: in POLY at QUALITY HI, presets that use DOUBLE (Brass
  Choir, Horn Bloom) could crackle on a busy computer as voices ran out of time. DOUBLE's voices
  are now shared out among the processor's threads more evenly, so far fewer are dropped. A
  computer too slow for all the voices can still drop some; QUALITY LO is the lighter choice.

• Fewer dropouts in the standalone on a busy Linux computer: its audio thread ran at
  ordinary priority, so other work on the computer could hold it up past its time, whatever the
  preset. It now runs at real-time priority, as POLY's threads do, wherever the system allows
  it: on Linux, a user in the realtime or audio group, or through RTKit, which Ubuntu, Fedora
  and most desktops run and which the standalone now asks when the system refuses it directly
  (POLY's threads too). Where neither is there, a note after PANIC says so for a few seconds as
  it starts, with how to fix it, and SETTINGS and AUDIO & MIDI keep saying so; on macOS and
  Windows, which give it real-time priority themselves, nothing is shown. A block that an LFO or
  a macro cuts short, once it has run out of time, is no longer finished on one thread alone.

• Held keys in the Linux standalone: with TYPING on, a computer key held down was struck
  again many times a second once the computer's key repeat began, and holding Z or X stepped
  through the octaves. A held key now plays its note once, and Z and X move one octave a press,
  as on macOS and Windows; letting go still ends the note at once, and a key pressed again
  quickly still plays again. The standalone now also lets its typed notes go when its window
  loses the focus, as it does on macOS and Windows.

• Hosts that load the CA-72 on a smaller thread no longer crash. Creating or starting an
  instance needed more of the host's thread's stack than some hosts give (a macOS secondary
  thread has 512 KB), which could crash the host to the desktop. An instance's whole life now
  fits a thread of 256 KB, and the sound is unchanged.

• The Audio Unit at 96 kHz: a host that prepared the CA-72 from a thread with a small stack
  (as pluginval does) could crash it while it built its voices. They are now built on a thread
  of their own.

• The standalone quits after being hidden. On a Mac, a standalone application left hidden
  for some minutes while it played no audio (no audio device, or one that had stopped) was
  slowed by macOS's App Nap, and quitting it could stop at an error window ("Standalone shutdown
  did not finish within two seconds") instead of closing. It now always quits, its session saved,
  though macOS may take a few seconds to pass the quit on to an app it has been resting.

Free software under the GNU General Public License, version 3 or later. Copyright © 2026 Idle Foundry Ltd.