Apollo — Polyphonic Synthesiser for Eurorack · Two Engines, Eight Voices, MIDI

Launch price — £329. Apollo is hand-built here in the UK in small batches, and the first 25 go out at £329 as a thank-you to anyone coming along early. After that the price settles at £349.

Apollo is a polysynth, in a rack.

Eight voices, two engines running at once, twelve kinds of synthesis and a full stereo effects chain — played from MIDI, from a keyboard, or from four sequencer tracks at the same time. Chords, arpeggios, presets and modulation are all on board, so the instrument is finished before you patch anything into it.

Full user manual: Download Apollo 8-Voice Polyphonic Synthesizer for Eurorack

Two engines, twelve kinds of synthesis

Two engines run at once, independently, each with eight voices and its own filter, envelopes, level, pan and tuning. Set each to whichever synthesis suits the sound:

V-Analogue — two oscillators with sync, sub and unison 
FM — six-operator, DX-style, with the full bank 
Modal — struck, plucked and bowed resonant bodies, twelve materials and ten exciters 
String — Karplus–Strong plucks, bows and blows 
Drums — nine tuned drum kinds, eight-drum kits 
Tonewheel — a nine-drawbar organ with percussion 
Wavetable — thirty-two morphing sets with a position LFO 
Phase Dist — CZ-style phase distortion 
Additive — partials, tilt, odd/even and comb 
Formant — vowel and voice synthesis 
Waves — the four classic shapes, done properly 
Noise — white and pink through the engine filter

Engine 1 can cross-modulate engine 2 by linear through-zero FM or AM, tapped before its level — so an engine set silent is still a full-scale modulator.

And every engine is loudness-matched to every other by measurement. Switching type is a musical decision again, not a trip to the output knob.

Four knobs that are always the right four

Apollo boots into its PLAY screen, and that is where it is meant to live.

Four knobs — A, B, C and D — sit on the sound in front of you, already mapped to the controls that define whichever engine you are on: a wavetable's scan, a modal body's material and strike, an organ's drawbars, an FM voice and its brightness. Nothing to bind, nothing to set up, nothing to remember. D does double duty as the value knob once you step into the edit menus, so the hand that was playing the sound is the hand that changes it.

Eight pages carry the rest under the same four knobs: levels, both envelopes, the filter, the effects, the granular section and the engine's pitch placement. The four assignable CV inputs pin straight onto the Sound page's axes. The depth is all still there — the matrix, the operator envelopes, the mode tunings — but it sits behind the instrument rather than in front of it.

Eight layers, four tracks, one module

Eight multitimbral slots sit over the default layer, each with its own MIDI channel, CV input or note range. A four-track sequencer into the four CV/gate pairs plays four lines at once; a DAW on four MIDI channels does the same.

Or ignore all of it: a note is a note, and out of the box every input plays the same eight voices and the same sound with no setup at all.

One trigger, a whole part

The chord engine turns a single gate into a voicing — including just-intonation and harmonic stacks — and can advance the chord type on every note, so a plain sequencer track walks a progression. The arpeggiator then takes whatever is held and spreads it, with harmony, strum, pedal-point, ratchets and generative variation. And on the struck engines, notes decay naturally long after the gate has closed.

A studio on board

A full stereo effects chain, all of it on the module: Age for the drift and wear of a well-used instrument, then bitcrusher, filter and drive, phaser, granular, delay, reverb, chorus and glitch. Every effect has its own wet and dry, and every parameter is a modulation destination.

The granular engine

The granular section is the one to go and find first.

It sits in the middle of the chain, after the filter and phaser and before the delay and reverb — so it granulates the whole instrument, both engines together, and the grains then land inside the delay and the reverb rather than being sprinkled over the top of them. Audio runs continuously into a capture buffer, and grains are read back out of it with Hermite interpolation, up to eight overlapping at once.

• Position — where in the buffer the grains are read from: hard right is the audio you just played, hard left is the oldest still held.
• Size and Density — from single isolated grains drifting past with silence between them, to a solid cloud.
• Pitch — ±2 octaves, and Jitter scatters it per grain, so one setting gives a chorus of pitches rather than a transposition.
• Spray — scatters where each grain starts reading, smearing a tight loop into a wash.
• Texture — opens the grain window from a soft Hann curve towards a near-boxcar, which is the difference between a breath and a stutter.
• Random — moves the spawn clock from strictly periodic to Poisson, so the cloud stops sounding machine-timed.
• Grain arpeggio — steps each successive grain up or down by up to an octave over a settable number of steps, turning a held buffer into a figure.
• Freeze — stops the capture. What is in the buffer stays there, and everything above keeps working on it, indefinitely. Play on top of it with the instrument it came out of.
• Fine and Long modes — a short buffer with full bandwidth for stutters and glitches, or a four-times-longer one for pads and drones.

Four of these sit on the knobs on PLAY's own Granular page, and every single parameter is a modulation destination — so Position can be swept by an envelope, Freeze triggered from a gate, Density tracked from a CV input.

Modulation and memory

Four mod sources — LFOs, sample-and-hold, random, envelopes, probabilistic gates and Euclidean patterns — plus two mod envelopes, feeding a sixteen-slot matrix that reaches every parameter in the instrument. Each routing can be aimed at engine 1, engine 2, or both. The four assignable CV inputs can take any parameter over outright as a hands-on control.

Presets store the whole instrument: both engines, the filters, the envelopes, the modulation, the arpeggiator, the chords and every effect. Program Change recalls them. The module keeps its state through power-off exactly as you left it, edited or not.

Specifications

• Eight-note polyphony; two independent digital engines, eight voices each — sixteen voice instances at full polyphony
• Twelve synthesis types, all resident and switchable from the panel
• Per engine: multimode filter (LP/HP/Band/Notch) with drive, VCA and VCF envelopes, level, pan, octave/semitone/JI/fine tuning, glide
• Eight multitimbral layers by MIDI channel, CV input or note range
• Chord engine with sequencing, just-intonation and harmonic chord types
• Polyphonic arpeggiator with harmony, strum, pedal-point and generative variation; internal, MIDI or gate clock
• Four mod sources, two mod envelopes, sixteen-slot modulation matrix with per-routing engine scope
• On-board stereo effects: age, bitcrusher, filter/drive, phaser, granular, delay, reverb, chorus, glitch
• Preset memory with factory and user banks; Program Change recall
• Inputs: MIDI IN; 4 × 1V/oct; 4 × gate; 4 × assignable CV
• Outputs: main out; MIDI OUT (thru plus arpeggiator and chord notes); 2 × modulation out
• Controls: four knobs (A–D; D doubles as the value knob in the edit menus), master tune, DATA encoder, OLED display
• 44.1 kHz
• Format: Eurorack, 19 HP
• Power: +12 V @ 150 mA, −12 V @ 40 mA

Taxes and shipping

UK orders: All applicable UK taxes are included in the price shown and there are no additional UK taxes or import charges to pay on delivery.

International orders: Customers outside the UK are responsible for any import duties, VAT, sales tax, customs charges, brokerage fees or other charges imposed by their country of import.

Buy with confidence

• 30-day no-quibble returns — changed your mind? Send it back.
• Two-year guarantee on every module.
• Faulty in the first six months and we replace it, not repair it.
• Free firmware updates for life.