FireFlow · Build log

A small ambient groovebox where modulation is the instrument.

The instrument already plays. The software is well underway; now the work is turning it into hardware — a compact performance box currently being planned for the bench.

Play it in VCV Rack See prototypes Code on GitHub

A large hybrid groovebox prototype on a blue electronics work mat. — A hand-built hardware prototype on the bench — and the firmware it led to, playable today as a VCV Rack module.

The current FireFlow VCV Rack plugin panel: one unbroken dark surface, its two mirrored decks marked by softly lit mint and orange fields with a neutral centre column between them. — A hand-built hardware prototype on the bench — and the firmware it led to, playable today as a VCV Rack module.

Track 1 of 10

The New Init Patch

0:006:35

Roadmap · Aug 2026 — May 2027

Nine months from a plan to an instrument you can play.

Three hardware milestones, two board revisions and 23 April as a target corridor rather than a deadline — the dates past the panel freeze get re-anchored once that freeze happens. The graphic below is drawn in two materials, because hardware time comes in two kinds. It is not redrawn when reality overtakes it; it gets corrected by hand, in red, the way a plan on paper would.

Weeks I workWeeks a factory worksMilestoneDecisionwhat actually happened

H16 Nov 2026The prototype plays

A ten-euro test board and a lasered acrylic panel with real knobs on it. Not pretty, but playable — and the panel layout freezes the same day.

Two acrylic plates later, the layout froze on 13 Oct.

H212 Feb 2027The first real PCB

Two boards and an aluminium front panel, built and measured. Every fault goes on a list; nothing gets fixed in place, or the next revision never ships.

Rev A and the aluminium plate: both ordered 13 Oct.

H39 Apr 2027The finished PCB

One correction round, assembled and tested. After this the only work left is firmware, a demo set, and packing a case.

Target23 Apr 2027An instrument that plays

A corridor, not a deadline — re-anchored once the panel layout freezes; the regrouping rounds in Rack come first, before H1. Superbooth opens two weeks later. There is no booth booked and none required; the fair is what happens afterwards.

Re-anchor once Rev A is measured.

63 of those 259 days are spent waiting. Boards take three weeks to come back from a factory, and no amount of enthusiasm shortens that — which is why the schedule is built backwards from the last day, and why the cheapest board in the plan is the first one.

Build log

Build log — in the open

Building in public, in eighteen chapters — from the first commit to the whole engine playing on real hardware. Start with what happened last, or open any chapter below.

mcbronkowitch/fireflow89 entries · 52 days · 60 takes

Latest entry28 Oct 2026

Where you left it

Until today every power cut was a factory reset. Now the board remembers. The knobs speak for themselves at boot; the flash keeps what they can't show, like the 50 depths under MOD. It saves once the knobs have been still for 15 seconds…

Chapter 18 · It runs · CPU hunt, part IIItakepanel

Read this entry Hear the take

Every chapter

89 entries in 18 chapters · open one to read its entries

Order

18It runs · CPU hunt, part III523 joints by hand, Rev A boots with its keys the wrong way round, and every knob at noon sends the CPU hunt back to work24–28 Oct · 4 entries
1. 28 Oct 2026Where you left ittakepanelnewest
2. 27 Oct 2026Seven quiet ones
3. 25 Oct 2026Noonpanel
4. 24 Oct 2026523 jointspanel
Read chapter 18 in full
17The board nobody drewRev A goes from a sentence to a set of fab files, the first acrylic plate says its rows are too tight to play, the second one finally lets a whole hand in, and the aluminium one arrives with gummy bears, the boards right behind it3–21 Oct · 6 entries
1. 21 Oct 2026Nerd? We prefer the term intellectual badasspanel
2. 13 Oct 2026The real panel is orderedpanel
3. 13 Oct 2026Room for a whole handpanel
4. 9 Oct 2026Nine millimetres of elbow roompanel
5. 7 Oct 2026I blew itpanel
6. 3 Oct 2026Rev A is a file now, and a quote says what it costspanel
Read chapter 17 in full
16Anything but the multiplexerTwo mux breakouts lie on the desk, and everything else gets built instead — a drone engine deleted the same week, an FM engine, a handful of new controls and a plate that becomes one dark surface — until a test board arrives from the fab, gets soldered by hand, and on the last day three of its pots play deck A18 Aug–28 Sep · 15 entries
1. 28 Sep 2026Five rounds with a probe, and the coupon answers
2. 17 Sep 2026The SMD boss, first trypanel
3. 16 Sep 2026Board one, and nothing caught firepanel
4. 15 Sep 2026The boards are here, and I cannot read thempanel
5. 3 Sep 2026Eight dollars of real hardware, and an argument about SMDpanel
6. 30 Aug 2026The plate stops being a blueprintpanel
7. 30 Aug 2026PAN, and the room stays where it istakepanel
8. 29 Aug 2026TAME, built twice and kept neitherpanel
9. 29 Aug 2026Left of noon, and every depth knob grows a second halftakepanel
10. 23 Aug 2026The plate stops fidgetingtakepanel
11. 23 Aug 2026PULL, and the bass takes the chords with ittakepanel
12. 22 Aug 2026Hold MOD, and every ring becomes a depthtakepanel
13. 22 Aug 2026The two decks stop ignoring each othertakepanel
14. 21 Aug 2026I opened Rack at three percent motivation, and it was already doing ittakepanel
15. 18 Aug 2026What I built instead of measuring a multiplexertakepanel
Read chapter 16 in full
15The plate starts talkingTen LEDs were drawn on the hardware panel and six of them could not light at all — now nineteen lamps read the modulation rather than the knobs, and a take from the same morning turns out to be the same thing heard instead of seen16 Aug · 1 entry
1. 16 Aug 2026Nineteen lamps, and each one answers the question asked where it sitstakepanel
Read chapter 15 in full
14The accentA pattern that played every note exactly the same finally stops doing that — the first note keeps full strength, DENSE decides how many quieter ones join it, DEC decides how much room they have, and a note played by hand stops borrowing the sequencer’s last one16 Aug · 1 entry
1. 16 Aug 2026Every note struck the sametakepanel
Read chapter 14 in full
13The plateGlow comes out of the tree and half of it turns out to be a front panel for a module nobody will build — then the modulation layer finally learns to go slow, a knob that never had a behaviour gets one, the panel groups draw their own shapes and the result looks like a children’s toy, and the patch you boot into is a different instrument again14–15 Aug · 6 entries
1. 15 Aug 2026The plate went darkpanel
2. 15 Aug 2026It boots as something else againtakepanel
3. 15 Aug 2026Nobody drew these shapespanel
4. 15 Aug 2026The knob had no behaviourpanel
5. 15 Aug 2026Nothing here could slow downpanel
6. 14 Aug 2026Half of it was one filepanel
Read chapter 13 in full
12The planA date nobody handed over, three hardware milestones, seventy-seven days of waiting for a factory — the panel question answers itself at 60 HP, the first drawing of it is honestly ugly, the second one has an opinion, the instrument that answers at boot is a new one, and then the last lead goes flat7–14 Aug · 8 entries
1. 14 Aug 2026No further readingspanel
2. 10 Aug 2026Maybe tofu is not as dead as we thoughtpanel
3. 10 Aug 2026A different instrument answerstake
4. 10 Aug 2026The size of a knob is a claimtakepanel
5. 9 Aug 2026The first draft, as ugly as it ispanel
6. 8 Aug 2026Tofu is deadpanel
7. 7 Aug 2026The first cycles ever counted on the real boardpanel
8. 7 Aug 2026The date is mine nowpanel
Read chapter 12 in full
11The compact moduleSix knobs, one button, a machine that rolls the instrument underneath them — and a day later, v2.20.0 ships it as alpha 0.15–6 Aug · 2 entries
1. 6 Aug 2026Glow, alpha 0.1 — it makes sound, and sometimes it makes tofutakepanel
2. 5 Aug 2026GlowFlow — six knobs and one buttonpanel
Read chapter 11 in full
10StandaloneThe residency said no — the ledger, a fork that is no longer a fork, and the last entry on this site4 Aug · 1 entry
1. 4 Aug 2026Not selectedpanel
Read chapter 10 in full
09The bucket brigade · CPU hunt, part IIFLUX stops being tape, two days paying the CPU bill, a delay too strange to stay an effect, and two cracks somebody else found28 Jul–3 Aug · 6 entries
1. 3 Aug 2026Every knob says what it doestakepanel
2. 3 Aug 2026Somebody read the whole thingtakepanel
3. 2 Aug 2026Too strange to be an effecttakepanel
4. 30 Jul 2026Two days, nothing to heartakepanel
5. 28 Jul 2026It boots hummingtakepanel
6. 28 Jul 2026The clock is the instrumenttakepanel
Read chapter 09 in full
08BODYA resonator from string to bell — one voice per deck, and cheaper than the one it replaces27 Jul · 1 entry
1. 27 Jul 2026The engine with no oscillatortakepanel
Read chapter 08 in full
07The third engineA wavetable scanner, a song form, first sound on the Seed, lanes on the grid and off it25–26 Jul · 7 entries
1. 26 Jul 2026Now let them freelancetakepanel
2. 26 Jul 2026The lanes stop freelancingtakepanel
3. 25 Jul 2026It runs on the Seed
4. 25 Jul 2026Three the same, then a turnaroundtakepanel
5. 25 Jul 2026The knob we forgot to buildtakepanel
6. 25 Jul 2026The bootloader said yes and meant notakepanel
7. 25 Jul 2026We changed one part and got a new instrumenttakepanel
Read chapter 07 in full
06The samplerGrain cloud, a new co-author, Groovagene, a grid that swings20–24 Jul · 6 entries
1. 24 Jul 2026It grooved. Now it swings.takepanel
2. 23 Jul 2026We don’t need a Morphagene. We need a Groovagene.takepanel
3. 22 Jul 2026The sampler engine ships. So do its crimes.takepanel
4. 22 Jul 2026The sampler works. That’s the problem.takepanel
5. 21 Jul 2026Somewhere in entry 25, I became wetakepanel
6. 20 Jul 2026The grain cloud lived forty-one hourstakepanel
Read chapter 06 in full
05Macros & the panel · CPU hunt, part IChords without a chord mode, 160% of a chip18–19 Jul · 4 entries
1. 19 Jul 2026160% of a chip that only has 100panel
2. 18 Jul 2026The knob is the centre, not the ceilingtakepanel
3. 18 Jul 2026Infinitely many knobstakepanel
4. 18 Jul 2026Chords, without a chord modetakepanel
Read chapter 05 in full
04Making it playableGroove instead of dice, CHOKE, a cutoff you can grab16–17 Jul · 6 entries
1. 17 Jul 2026How wild, how fastpanel
2. 17 Jul 2026The cutoff you can grabpanel
3. 16 Jul 2026Only one may speaktakepanel
4. 16 Jul 2026A melody allowed to fidgetpanel
5. 16 Jul 2026A groove instead of a dice rollpanel
6. 16 Jul 2026One switch, two worldstakepanel
Read chapter 04 in full
03Finding the voiceA workbench in VCV, and a melody that finally sang14–15 Jul · 4 entries
1. 15 Jul 2026The reverb that moonlights as a delaytakepanel
2. 15 Jul 2026The melody sings now
3. 15 Jul 2026The workbench moved into the computerpanel
4. 14 Jul 2026The melody didn’t singpanel
Read chapter 03 in full
02Sequencing & roomCapture, entropy, the center section, a rebuilt reverb12–13 Jul · 5 entries
1. 13 Jul 2026One knob loudertakepanel
2. 13 Jul 2026Ambient reverb, rebuilttake
3. 12 Jul 2026Center sectiontakepanel
4. 12 Jul 2026Entropy sequencertake
5. 12 Jul 2026Capture sequencertake
Read chapter 02 in full
01The engineFork, five lanes, quantizer, first offline render10–11 Jul · 6 entries
1. 11 Jul 2026Polyphonic synth voicetake
2. 11 Jul 2026Effects & modulationtake
3. 11 Jul 2026Scales & quantizationtake
4. 11 Jul 2026First offline releasetake
5. 10 Jul 2026First tests
6. 10 Jul 2026Forked
Read chapter 01 in full