AT42

Get the highlights.

Light you can play. With MOD on, each drone follows its orb: ambient light, the shadow of your mouse and the red LED inside.

Thirteen cartridges. Two effect engines with 39 programs: shimmer, reverse delays, ring mods, crushers and more.

Twelve plates and a screen. 19 scales, an arpeggiator and a 16-step sequencer on the touch keyboard.

Sixty-two jacks. Every control voltage is patchable, and the internal normals keep it playing without a single cable.

What the original doesn't do. MIDI, host sync, chromatic drones, 30-second releases and stereo width.

The film.

AT42 rendered in 3D, in three shots. The sound is the engine playing Cathedral of A, a drone preset.

Oscillators that drift like the real ones.

Each drone oscillator is a single-transistor relaxation circuit: a capacitor charges toward the supply and discharges at breakdown. AT42 models that curve, so the VOLT knob lowers the supply, stretches the period and, past halfway, lets the five oscillators pull on each other.

Every classic voice has its photo-sensitive orb. Turn on MOD and the pitch follows the light: the ambient light setting, the shadow of your mouse over the orb, and the red LED inside it, driven by any CV.

Drone voices: 4 voices of 5 sawtooth oscillators with the tune ranges of the original, from 16 Hz to 2.3 kHz
VOLT: transposes the whole voice down and, past half travel, cross-modulates its oscillators
Photo orbs: light-dependent pitch with the slow release of a real light-dependent resistor
Noise voices: the Papa Srapa design: square modulator and tone oscillator with FM, AM, noise and sample and hold
VCOs: six waveforms including two morphing shapes, linear FM, hard sync, 8-position octave, ADSR with hold and loop
Filters: dual 12 dB Polivoks with slew-limited integrators, low-pass or band-pass, and stereo distortion
Effector: two engines and 13 cartridges of 3 programs: reverbs, shimmer, pitch and reverse delays, ring mods, crushers, generators

20

drone oscillators with light orbs

62

jacks with the hardware's normals

39

effect programs on 13 cartridges

28

presets, from cathedrals to techno

Hear it.

Every clip is the engine on its own, playing a factory preset from a MIDI file written for it. Nothing added afterwards, only the level matched across clips. Download the MIDI and play it through the preset yourself.

Cathedral of A
Two drone voices tuned to A, through the shimmer cartridge.

0:24 MIDI
Microtonal Fog
The LFOs light the orbs; the drones drift with the light.

0:24 MIDI
Birds at Dusk
The two noise voices with FM and AM: chirps and calls.

0:20 MIDI
Berlin Five
The 5-step sequencer drives both VCOs and opens the filter.

0:20 MIDI
Flute Lead
VCO A on the touch keyboard, in the minor pentatonic scale.

0:14 MIDI
Arp Constellation
Chords through the touch keyboard's arpeggiator, over a drone.

0:12 MIDI
Ocean of Noise
Filtered noise swept by two slow LFOs.

0:22 MIDI

Sixty-two jacks, with the hardware's normals.

Every control voltage has its jack: LFO A and B, the joystick, the 5-step sequencer and its pulser, the envelope follower, the drone envelopes, the sample and holds, and the touch keyboard's pitch, gates and pressure. Unpatched inputs keep the original's internal connections, so the instrument plays before you plug anything. Cables hang with real physics, and outputs take stacked plugs.

Twelve plates and a little screen.

The touch keyboard quantises to 19 scales, arpeggiates in five directions and records a 16-step sequence, with portamento, vibrato and five pressure modes. Its pitch and gate are normalled to both VCOs, and MIDI notes play it too.

Scales. Semitones, the seven modes, blues, pentatonics, Japanese, Gamelan, Gypsy, Arabian, Flamenco, whole tone. All 12 plates follow the scale.
Arpeggiator. Forward, backward, ping-pong, random or in the order played, with hold and clock division.
Sequencer. Record up to 16 notes from the plates; the active plate transposes the pattern.
Clock. Internal tempo, your DAW's tempo, or any clock patched into the clock input.

What the SOLAR 42 doesn't do.

A Settings page, drawn like the panel, adds what owners ask for most.

MIDI. Notes play the touch keyboard, C1 to F1 play the drone keys, pitch bend bends the VCOs, the mod wheel moves the joystick, and MIDI learn works on every control.
Host sync. LFO A and B, the pulser and the keyboard clock can follow your DAW.
Chromatic drones. Snap the drone oscillators to semitones, or keep the original analog tuning.
Longer releases. Drone envelopes up to 30 seconds.
Stereo width. A WIDTH knob before the filters and the effector, from mono to twice as wide.
Presets and colours. Save patches with their cables and keyboard sequence, roll a random patch, and pick a panel colour.

AT42 Settings page — The Settings page: character, sync, touch keyboard, expression, MIDI and system.

Drones, storms, sirens and sequences.

6

Drones

Chords tuned on the real tuning curve, from cathedrals to saturated swarms.

5

Ambient

Shimmer, breathing orbs, tape memory and an ocean of noise.

5

Sci-fi

Sirens, birds at dusk, a space monster and volleys from the noise voices.

3

Sequences

Patched with cables: Berlin-school, ritual pulses and a techno monster.

5

Keys

Flute leads, arpeggios, binaural VCOs and pressure pads from the touch keyboard.

4

Experimental

Piezo percussion, joystick spaces, ring bells and crushed choirs.

Pick a colour.

Cream

Tech specs.

Sound engine

4 drone voices of 5 negistor-style saw oscillators, VOLT coupling, light orbs
2 Papa Srapa noise voices with FM, AM, noise and sample and hold
2 AS3340-style VCOs with 6 waveforms, linear FM and sync; ADSR with hold and loop
10-channel mixer, dual Polivoks filter (LP/BP) with distortion
Dual effector: 13 cartridges × 3 programs
1x, 2x or 4x oversampling

Control

LFO A and B, joystick, 5-step sequencer and pulser, preamp and envelope follower
Touch keyboard: 19 scales, arpeggiator, 16-step sequencer, pressure
6 drone keys, 62-jack patch bay

Extensions

MIDI notes, drone keys, pitch bend, mod wheel and MIDI learn
Host sync for LFOs, pulser and keyboard clock
Chromatic drone tuning, 30 s releases, stereo width
Four panel colours

Formats

VST3, Audio Unit (macOS) and standalone app, with stereo audio input

Minimum

macOS Mac with Apple silicon (M1 or later), or Intel Core i5 quad-core from 2017 or later, with macOS 11 Big Sur or later.
Windows PC with Intel Core i5-6500 (6th generation, 2015) or AMD Ryzen 5 1600, or better, with Windows 10 or 11, 64-bit.
4 GB of RAM, a 1280 × 800 screen and a 64-bit host for VST3 or Audio Unit, or the standalone app.
Disk space: 125 MB on macOS (all formats), 42 MB on Windows.

Measured CPU load

Setting	Apple M4	AMD Ryzen 9 5900XT
Two drone voices with effects, 2x	2.6 %	7.9 %
Every voice and the effector, 2x	2.6 %	7.5 %
Every voice and the effector, 4x	4.8 %	14.5 %

Percentage of one CPU core at 48 kHz, sound engine only. With the editor open, the interface adds about 11 % on the M4. Hosts run each instrument on one core, so single-core speed is what counts.

Download AT42 1.0.3.

Free, no account, no activation, no telemetry.

macOS

macOS 11 or later. Apple silicon and Intel in one universal binary. VST3, Audio Unit and standalone app. 105 MB.

Download for macOS

How to install

Unzip the file.
Copy AT42.vst3 to ~/Library/Audio/Plug-Ins/VST3.
Copy AT42.component to ~/Library/Audio/Plug-Ins/Components.
Rescan plugins in your DAW. In Ableton Live: Settings, Plug-Ins, Rescan.

Windows

Windows 10 or 11, 64-bit. VST3 and standalone app. 35 MB.

Download for Windows