Manual

For Carnac OS 0.9.3. The FM1's panel, sounds, sequencer and presets, as the firmware has them today. New to the panel? The button guide shows what each button does.

Introduction

Carnac OS turns the M-VAVE FM-1 into an eight-voice wavetable synthesizer with two layers, a four-lane sequencer, a chord arpeggiator and a stone-circle-themed screen. It is built on the X0X platform and takes its name from the megalithic alignments at Carnac.

This manual follows the instrument as it is today. Every change is logged in the Changelog at the end, so you can see what moved since you last read it.

• Controls are named as they appear on the FM-1 panel: ten section buttons, a Select Encoder, an Algorithm Encoder, a Preset Encoder, four knobs, OCT- and OCT+, PLAY and REC, and the keyboard.
• Parameter names are written in capitals, as they appear on screen (CUTOFF, SPREAD, PRESCALE).
• Values run 0 to 127 unless a section says otherwise. Bipolar values show as -64 to +63, with 0 in the middle.

Getting started

Carnac starts on the HOME screen in SINGL mode: one layer, all eight voices, ready to play from the keyboard.

1. Play. Press keys. The note keys sound the focused layer.
2. Load a sound. Turn the Preset Encoder. A full-screen preset list opens and stays up for two seconds after the last click, and each click loads the next stored patch.
3. Shape it. Press FX for the oscillators, SEL for the filters, ENV for the envelopes, LFO for the LFOs. Press the same button again to step through that section's pages.
4. Turn the knobs. The four knobs set the four values shown at the bottom of the page.
5. Browse a page's other settings. Turn the Select Encoder. A list of the page's rows opens over the whole screen; the Algorithm Encoder changes the highlighted value.
6. Save it. Press SAVE. The button flashes while a save is armed; press it again to confirm (see Presets and saving).

To play two sounds at once, change PERF MODE on HOME from SINGL to DUAL or SPLIT. Layer 2 is unavailable in SINGL.

Panel and controls

Ten section buttons open the pages. Pressing a button again moves to its next page; hidden pages (for example OSC2 in SINGLE) are skipped.

Encoders and knobs

• Select Encoder moves through the rows of the current page. Each click opens a full-screen list of the page's rows; it closes 1.5 seconds after the last click, or when you touch another control.
• Algorithm Encoder changes the highlighted value. It keeps the list open while you turn it.
• Preset Encoder loads the next or previous stored preset. What it loads depends on the page: a layer patch on the sound pages, a performance on HOME, an arp pattern on ARP, a sequencer slot on SEQ.
• Knobs 1 to 4 set the four values on the page. Hidden or unused knobs are drawn greyed.

Shortcuts

• HOME + OCT- or HOME + OCT+ switches focus to layer 1 or layer 2. HOME acts when you release it, and not at all after a chord. After 200 ms of holding HOME, the focused layer's OCT LED lights and the other flashes. Layer 2 is refused in SINGL mode.
• SAVE + OCT- copies what SAVE would save on this page; SAVE + OCT+ pastes it (the save page opens and asks first). SAVE acts when you release it. Holding HOME or SAVE for 200 ms shows a strip at the bottom of the screen naming what OCT- and OCT+ do.

Lights. Only the button for the current page is lit. While the sequencer or arpeggiator plays, its button (SEQ or ARP) blinks on the beat, lit for the first half of each quarter note, even when its page is open. MIDI clock out (GLOBAL > CLOCK OUT) goes out on USB.

Transport. PLAY starts and stops the sequencer on the SEQ page and the arpeggiator on the ARP page. On any other page it starts both, or stops whichever is playing. The PLAY light shows what PLAY would stop. One started while the other plays waits for the other's next bar, so they stay in time. REC arms recording on the SEQ and ARP pages.

Voices and layers

Carnac has eight physical voices shared by up to two layers. Each layer plays its own patch, with its own architecture, filters, envelopes and effects sends.

Performance mode (HOME, PERF page)

• SINGL: one layer, using every voice the architecture allows.
• DUAL: each layer has its own MIDI channel. The FM1's keys play the layer you have selected, so you hear the layer you are editing (both layers when the two share a channel). External MIDI reaches each layer on its channel.
• SPLIT: layer 1 and layer 2 share the keyboard. The ZONES page (HOME) sets, on its four knobs, SPLIT NOTE and SPLIT FADE (by note) and VEL SPLIT and VEL FADE (by velocity).

In DUAL and SPLIT the voices are shared out: layer 1 gets half rounded up, layer 2 half rounded down, based on the smaller of the two layers' caps. MAX VOICES on the LAYER page shows the result.

Architecture (ARCH on the LAYER page, for the focused layer) decides the signal path of every voice, and the most voices it may use.

The caps keep the FM-1 within its processing budget. Carnac uses both of the FM-1's cores, and lightens the load by itself rather than drop out if the processor gets close to its limit.

ANALOG (L1 ANALOG and L2 ANALOG on the LAYER page, right after ARCH) makes the layer behave more like an analog synth. It is stored with the patch. Each voice gets its own small fixed tolerances: pitch, cutoff, resonance, envelope speed and level. Each note scatters them a little. From 40 up, slow drift eases in as well. At 0 the layer is exact.

Voice mode (L1 VOICE MODE, L2 VOICE MODE): MONO RETRIG, MONO LEGATO, POLY REUSE, POLY RESET or UNISON. In UNISON, UNISON DETUNE spreads the outer voices by up to 50 cents. In SPLIT, layer 2 uses layer 1's voice mode.

Glide. PORTA MODE is CONST RATE, CONST TIME or LEGATO TIED, and PORTA TIME (knob 4 on the LAYER page; 0 is no glide) sets how long it takes. In polyphonic modes the glide starts from the last note played on that layer. A chord (notes within 30 ms of each other) fans out from the note played before it.

Layer focus. The sound pages edit the focused layer. Switch with HOME + OCT- (layer 1) or HOME + OCT+ (layer 2). The screen uses one colour scheme for both layers, set by THEME.

Oscillators and filters

Oscillators (FX button)

OSC1 and OSC2 play a wave from the WAVE list: first the 16 wavetable banks (MENHIR to HEARTH, then HOLLOW REEDS, breathy flutes), then the PCM waves, then the 20 attack sounds as one-shots. OSC2 appears only in architectures that use it (DUAL OSC and STACK).

• Knobs: WAVE SCAN (position within the wavetable), OCTAVE (-3 to +3), FINE TUNE (up to 7 semitones up or down, finest near the centre, shown in cents), PITCH MOD (amount).
• Rows: WAVE, SCAN MOD SRC and AMT, PITCH MOD SRC, KEY TRACK, and on OSC2 OSC SYNC. In SINGLE, SPREAD and STRIKE, knob 3 is SCAN AMT (the scan's mod amount) and FINE TUNE is a row.

PCM waves. A PCM wave is a recorded sound: an optional attack, then loop A and an optional loop B. WAVE SCAN crossfades from loop A to loop B, and the attack plays again on every new note. SPREAD works on PCM waves too, with four detuned playheads per loop. FM cross-modulation works on them; PM and OSC SYNC do nothing.

The PCM waves live in their own flash areas, beside the firmware. The web installer writes them after the firmware; without them a PCM wave plays the first wavetable bank instead.

OSCMIX mixes the oscillators, the sub oscillator and the noise. Its four knobs change with the architecture:

Cross-modulation types are FM, AM, RING and PM. The sub oscillator sits one or two octaves down (SUB OCTAVE) and is a SINE, a SQUARE, or CURRENT, a copy of OSC1's live wavetable frame. Noise colour morphs from white (0) through pink (64) to brown (127). In BINAURAL, BEAT HZ offsets the right ear's pitch by up to 31.75 Hz.

In STRIKE, each new note starts with a short attack sound layered over the wavetable, the way an LA synth puts a sampled attack in front of its tone. A note played legato over a held one keeps the running attack. STRIKE adds an ATTACK page to the FX section, between OSC1 and OSCMIX; its screen shows the sound's outline, dim at full length and bright as it will play.

Filters (SEL button)

FILTER1 and FILTER2 share the same controls. FILTER2 appears in DUAL FILT and STACK.

• Knobs: TYPE MORPH (labelled by what it does in the circuit: LP-BP-HP, MODE or SPREAD), CUTOFF, RESONANCE, MOD AMOUNT.
• Smoothing: CUTOFF, RESONANCE and TYPE MORPH (and OSC SCAN) glide to a new knob value over about 25 ms, so a slow turn sweeps smoothly. Loading a patch or performance jumps straight to its values.
• DRIVE (the first row) sets how hard the signal goes into the circuit, from clean at 0 to driven hard at 127. The level stays roughly even as it turns, so it adds grit rather than volume.
• FLAVOUR (the second row) picks the circuit, and TYPE MORPH means something different in each.

KEY TRACK (the third row, after DRIVE and FLAVOUR) moves the cutoff with the note played, pivoting at C4. At 0 the cutoff stays put; at 127 it follows the keyboard one octave per octave.

The filter mixer (FLTMIX) appears in DUAL FILT (BALANCE, ROUTING from serial to parallel), STACK (BLEND A/B, WIDTH, ENV3>CUTOFF) and BINAURAL (FLT PHASE, WIDTH, CUTOFF L/R, PHASE MOD).

Modulation

Almost every destination in Carnac has a MOD SRC row (which source drives it) and an amount. Sources are: none, velocity, keyboard, mod wheel, aftertouch, ENV1 to ENV3, LFO1 to LFO3, MODSLOT1 to MODSLOT3, and CUSTOMCC1 and CUSTOMCC2. The two custom CC numbers are set on the GLOBAL page; the CC1 knob on the LAYER page sets CUSTOMCC1 directly, with no number needed.

Envelopes (ENV button). Knobs are ATTACK, DECAY, SUSTAIN and RELEASE. Extra rows: VEL > TIME and KEY > TIME (bipolar), RETRIG RATE, RETRIG SYNC, LEGATO, AUTO DECAY (a rapid repeat of a note shortens the release) and, on ENV2 and ENV3 only, INVERT. ENV1 is hardwired to the amplifier. An inverted envelope is drawn upside down in the display, as its destinations receive it: full at rest, dipping with the note (in source).

LFOs (LFO button). Knobs are SHAPE (sine through slewed random), RATE, DELAY (above 100 the LFO runs in release mode) and FADE (negative fades out, positive fades in). Extra rows: SPEED MOD SRC and AMT, CLOCK SYNC, PHASE and KEY RESET. LFO1 is shared by all voices; LFO2 and LFO3 run separately in each voice.

Mod slots (EDIT button). Three slots, MOD1 to MOD3, each combining two sources into a new one that other destinations can then use. The knobs are SOURCE A, FUNCTION, SOURCE B and AMOUNT. AMOUNT starts at 0, and at 0 the slot does nothing.

• Functions: A * B, A + B, A - B, MAX, MIN, SAMPLE B ON A (B is held each time A crosses its middle), QUANTIZE B TO A (B sets how coarsely A is stepped), ABS(A - B), LAG (A slews, B sets how slowly) and DIODE (A - B with the negative half cut off).
• The page: the capstone shows the slot as an equation, such as LFO1 * ENV1. Below it, the portal at the centre shows the slot's recent output as rings radiating from a glowing eye. Around it stands a ring of stones, one for every destination the architecture has, always in the same place. A ray runs from the eye to each stone this slot feeds, carrying the slot's signal outward: the more the destination gets, the wider the ray swings and the brighter and taller its stone. A stone fed by another source is an outline; one fed by nothing is a low stub. At AMOUNT 0 the portal goes dark and the rays stop.
• Destinations: the line under the capstone names the stone you are on, with its amount if this slot feeds it, or the source that feeds it now (OFF for none).
• Editing destinations: turn the Select Encoder to walk round the ring, and the Algorithm Encoder to set the selected stone's amount. Turning the amount of a stone this slot does not feed routes the slot to it, starting from 0, and replaces what fed it before (the popup shows the destination). You can still route from each destination's own page by setting its MOD SRC to MODSLOT1, 2 or 3.
• With no note playing: velocity, keyboard, mod wheel, aftertouch, the envelopes, LFO2 and LFO3 belong to a voice and read 0 when nothing sounds, so the portal only moves while a note plays. LFO1 keeps moving without one.

• Knobs: SOURCE A, FUNCTION, SOURCE B, AMOUNT.
• Functions: a*b (with one source set, it passes that source), a+b, a-b, max, min, sample B on A, quantize B to A, |a-b|, lag and diode.

Pitch bend and mod wheel. The LAYER page's knobs are VELOCITY (the keys' velocity), MOD WHEEL, CC1 and PORTA TIME. Pitch bend comes in over MIDI only. BEND RANGE is on the GLOBAL page.

Effects

There is one reverb and one delay, shared by both layers. Each layer feeds them through its own sends on the AMP page (DELAY SEND and REVERB SEND). The effects settings are on the EFFECTS page (GLO button) and belong to the performance.

EFFECTS knobs: DELAY TIME, DELAY FDBK, REVERB TIME, REVERB DAMP.

EFFECTS rows: DELAY TYPE, DELAY SYNC, REVERB TYPE, REVERB PREDELAY, DEGRADE, PING PONG.

• DEGRADE is one control for wow, flutter and filtering. It drives both the tape and the BBD delay.
• PING PONG bounces the echoes between left and right.
• DELAY SYNC locks the delay time to the tempo.
• Self-oscillation. With FEEDBACK above 100, both delays build up on themselves, in a musical way. At the top of the range they run away to a dark, filtered howl, so turn it up slowly.

Very loud sends are limited before they reach the reverb and delay, so playing several voices into a hot reverb should not buzz. If you hear digital buzz or a high whine after a note ends, report it with the reverb type and the patch.

Sequencer and arpeggiator

SEQ: the four-lane sequencer

SEQ has four lanes of 16 steps. Each lane has its own event type, speed, direction and loop, so lanes of different lengths drift against each other. Press SEQ to open lane 1 with steps 1 to 4 on knobs 1 to 4; press SEQ again for the next lane (1, 2, 3, 4, then back to 1), keeping the same steps on the knobs. The keyboard's bottom 16 white keys are the lane's steps: the playhead lights brightest, the four steps on the knobs medium, and every other step that plays (inside the loop, not muted or skipped) dimly. Press a white key to put that step and the next three on the knobs (from step 13 on, steps 13 to 16). While the sequencer plays, the knob card of the step under the playhead is outlined, as on the ARP page.

Lane rows (Select Encoder, Algorithm Encoder):

Loops. Hold OCT- and press one of the 16 white keys to set the lane's loop start. Hold OCT+ for the loop end.

Step record. Press REC on SEQ, then play keys. Each note is written into every NOTE lane at the record step. Keys struck while others are still held build a chord of up to four notes. With PLAY and REC both on, the record step re-fires at each lane's PRESCALE rate on the clock, so it keeps sounding rather than playing once.

Scale mode. On a NOTE lane, SCALE holds the lane to a scale: OFF, GENRE (follows the arpeggiator's genre bank), Major, Minor, Dorian, Phrygian, Lydian, Mixolydian, Harmonic minor, Major pentatonic, Minor pentatonic or Blues. ROOT sets the tonic. Turning a step's note knob moves through the scale's degrees; played notes are snapped to the scale as you enter them. Stored notes are never changed, so turning SCALE off gives your original notes back.

ARP: the chord arpeggiator

ARP plays chord patterns of up to 8 steps. The lowest 13 keys are chord keys, and a chord key sounds the chord for its note from the current GENRE BANK. The next 8 white keys are step keys.

• Play live: hold a chord key.
• Capture a step: hold a step key and press a chord key. The chord and the four ARP knobs are stored in that step.
• Knobs: RATE (how fast the step's notes play: the length of one rhythm cell, 1/2 down to 1/128, with triplets; the rhythm repeats until the step ends), OCTAVE (1 to 4), STYLE (hold, block, up, down, up-down, down-up, random, strum up, strum down) and RHYTHM (24 patterns). HOLD strikes the chord once and holds it; while following steps play the same chord it is not struck again, at any TIMING and octave range. With HOLD, RHYTHM becomes STRUM: NONE, UP or DOWN, with the notes RATE apart.
• Function keys (the black keys among the step keys): LATCH keeps a live arpeggio playing after you let go. TIE carries the previous chord on. CLEAR makes a rest. COPY copies a step to others. ACCENT plays the first strike at ACCENT VEL.
• Rows: LAYER (L1, L2 or BOTH in DUAL mode), TIMING (every step's length, 2 bars down to 1/32T), GATE (how long each strike sounds, for the whole pattern), SEQ LENGTH (1 to 8), TRANSPOSE MAQ, GENRE BANK and ACCENT VEL.
• Record: arm REC. Playing, a chord key records into the nearest step. Stopped, chords fill steps 1, 2, 3 in turn.
• TRANSPOSE MAQ makes the sequencer's NOTE lanes follow each step's chord root and the chord key you press, so the arp and the sequencer stay in key together.

The GENRE BANK holds dozens of chord sets, from Pop, Jazz, Blues and House to Synthwave, Cinematic, EDM, Gospel, Lo-fi, Funk and Neo Soul.

Presets and saving

Carnac stores four kinds of thing, each in 128 slots:

Loading. Turn the Preset Encoder. It loads the kind that fits the page you are on: a patch on the sound pages, a performance on HOME, an arp pattern on ARP, a sequencer slot on SEQ. The preset list covers the whole screen and closes two seconds after the last click.

Links. HOME's PERF page, the performance browser, shows which patch, sequencer and arp slots the current performance uses: L1 PATCH, L2 PATCH, SEQ LINK and ARP LINK (its knobs), with PERF PRESET and PERF MODE as rows. Its dolmen draws the performance as a capstone on four pillars, one per part; a pillar is thicker the more its part holds, an outline while it is still factory-fresh, and the capstone thickens with the whole.

Saving.

1. Press SAVE. The save page opens on what the page you were on saves (a sound page: the focused layer's patch; HOME: the performance; SEQ; ARP) at the slot it came from. The header says it, e.g. SAVE L2 PATCH.
2. Pick the slot with the Algorithm Encoder or knob 2. The bottom of the screen shows the whole bank: a mark for each used slot, your slot as a standing stone, and the moon above it, full over an empty slot and a dark crescent when you would overwrite. The line under the name says EMPTY or OVERWRITES and the name there.
3. To rename, turn knobs 3 (position) and 4 (character); the letter keyboard shows while they turn. Names are up to 16 characters from letters, digits, space and . - _ /.
4. Press SAVE. An empty slot is written at once; a used one asks OVERWRITE? first (NO or YES with the Algorithm Encoder, then SAVE).
5. The screen reports SAVED NAME TO SLOT N, and the next control takes you back to the page you came from.

Copy and paste. Hold SAVE and press OCT- to copy what SAVE would save on the current page (the focused layer's patch, the performance, the sequence or the arp pattern). Hold SAVE and press OCT+ to paste it over the same kind, for example layer 1's patch onto layer 2: the save page opens and asks PASTE? first. While SAVE is held, a strip names both, with PASTE dimmed when the clipboard holds another kind.

Display and themes

The screen is mostly black, so the panel gives off little light when played outdoors at night. Text is set in a rune-style face, and every popup covers the whole screen. Pages are drawn with lines, lit stones and sparse fog rather than filled textures.

• Page header. The current section's pages are listed at the right, with the current one lit and underlined. The layer and architecture are at the left.
• Battery moon. The moon at the top right of every page shows the battery. It waxes with the charge: a dark new moon when empty, a full moon when full. Below a third of a charge it is lit pale. On a computer's USB power it is full with eight stars around it. Until the first reading it hangs full and unlit.
• Parameter popup (shown only while the Algorithm Encoder turns a value; the Select Encoder moves through the page's own list). Each row is a standing stone, with the cursor's stone lit. The value is a moon on an arch over the stones: the left horizon is the minimum, overhead is the middle (zero for bipolar values) and the right horizon is the maximum. The moon waxes on the way up and wanes on the way down.
• Preset list. The slot picked is marked by brightness.
• SEQ and ARP use the same colours as every other page and do not change with the layer.

THEME (HOME, GLOBAL page) sets the screen colour. It belongs to the instrument, so loading a preset never changes it. The CARNAC OS start-up screen is drawn in the theme you last chose.

System

GLOBAL page (the last page of HOME). Knobs: TUNE (MASTER TUNE, -50 to +50 cents), CURVE (VEL CURVE), CLOCK (CLOCK OUT) and TEMPO (INT TEMPO, greyed when following MIDI clock). Rows: MASTER TUNE, VEL CURVE (SOFT, LINEAR or HARD, applied to incoming MIDI notes), CLOCK OUT (OFF or USB: while the clock is internal, MIDI clock, start and stop go out on USB; the TRS jack only receives), MIDI CH LAYER1 and LAYER2, CUSTOM CC1 and CC2, BASE VELOCITY, BEND RANGE, CLOCK SOURCE (INTERNAL or MIDI), INT TEMPO and THEME. MASTER TUNE, VEL CURVE, CLOCK OUT and THEME belong to the instrument and survive power-off; the rest belong to the performance. The sequencer and arp follow the clock, internal or MIDI, and changing page never disturbs it.

Processing load. Carnac runs on both of the FM-1's cores. The sound is the same on one core or two. If the FM-1 gets close to its limit, Carnac lightens the load by itself rather than drop out, and the voice caps in Voices and layers keep the heaviest architectures inside the budget. On the device, eight SINGLE voices use about 43 percent of the processor. The heaviest combinations (SH-2 filters in DUAL FILT, STACK or BINAURAL, or heavy patches with the sequencer and arpeggiator running) reach 75 to 85 percent, where Carnac may lighten the load.

USB audio. Connected to a computer, the FM-1 is also a USB audio input: 16-bit stereo at 44.1 kHz, class compliant, so no driver is needed. It shows up as "Line (X0X FM-1)" and carries the same output as the jacks, after the MASTER knob. Record it in any audio app.

Installing and recovering. Install Carnac from the web installer at owenkirby.github.io/carnac-os, in Chrome or Edge, with the FM-1 on USB. It writes the firmware, checks the version, then writes the PCM waves. If an install stops part-way, replug the cable and start again: the FM-1 stays in update mode and the installer carries on. If the FM-1 does not start after an update, switch it off and on twice; it then starts in safe mode, which keeps USB working. The same page can put M-VAVE's stock firmware back. Deeper recovery steps are in the source repository (docs/fm1-recovery.md).

In the works

These features are in active development for future releases:

• MIDI Program Change: receive program change messages to load patches and performances from external MIDI controllers and sequencers.
• Full CC implementation: comprehensive MIDI CC support with the ability to map any CC number to any parameter, and record CC changes into sequences.
• Voice optimization: further refinements to voice allocation and voice-stealing algorithms for smoother, more musical note handling in dense polyphonic situations.
• MFX (Multi-Effects): additional built-in effects and modulation processing pathways under development.

Changelog

Newest first. Features marked in source are written but not yet installed on the FM-1.

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