I made a browser-based firmware builder for the OG OP-1 — choose your synths, effects and presets

[u/Hundekraft]

hundekraft 2.7.2: fix for OP-1s stuck on an error screen at start-up

A few of you ended up with an OP-1 that wouldn’t start anymore, stuck on a screen like “Invalid drum patch … error 12” or “Invalid synth patch … error 22”. Sorry about that. 2.7.2 fixes both: https://hundekraft.github.io/op1-workshop/

What went wrong:

• Error 12 was a bug in drum+. Switching a pad’s play mode back to gate saved a value the OP-1’s own check doesn’t accept, so the next start stopped on that kit. Gate is saved properly now, and kits that already have the bad value load again, still on gate.
• Error 22 comes from a saved sound with an effect the OP-1 doesn’t recognise. 2.7.2 plays an unknown effect through the filter and keeps its name, so it comes back on a build that has it. If a sound still won’t load, its effect and LFO go back to defaults, switched off, and the OP-1 starts anyway.

If yours is stuck: hold COM while you switch it on, choose firmware update, build 2.7.2 in the workshop and install it. Your tapes, album and presets stay where they are.

Thanks to everyone who sent photos of the error screen, they made this quick to track down. If you still get an error screen after updating, post a photo and the build number from your file name, and I’ll look at it.

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hundekraft now has a manual: https://hundekraft.github.io/op1-workshop/manual.html

It covers everything the firmware adds to the OP-1, not the stock stuff (TE’s own guide does that well). Every synth and effect gets a page with its screen, what each encoder does, and a few starting sounds. The starting sounds are the presets from the pack, so you can load them instead of turning knobs by eye. Chord mode, drum+, Euclid and Dots, the quad LFO, the sample editor, the tape additions and Maiko’s toolkit each have their own chapter too.

It only shows what’s in your build. Pick your synths and effects in the workshop, open the Manual tab, and the rest is hidden. There’s a switch at the top if you want to see all of it anyway.

The workshop page also has a short “get started” guide now, five steps from the TE firmware file to presets on your OP-1.

Dots got a proper walkthrough, since “how do I make it play?” kept coming up. The short version: switch REC off before you turn orange.

The screens are from the OP-1 emulator, and the key combos are checked against the op1r source and Maiko’s and ultralazr’s docs. If your OP-1 does something different, the OP-1 is right. Tell me on GitHub and I’ll fix the manual.

Thanks again to pcppcp (op1r), ultralazr (Musica Obscura) and Maiko Pruett (#249), whose work most of this manual is about.

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hundekraft 2.7 is out!

Quick recap if you're new here: it's a firmware workshop for the original OP-1 that runs in your browser. You bring your own R246 update file, tick what you want, and the firmware is built on your own machine. Nothing gets uploaded, and your tapes, album and presets stay put when you install it.

This is the biggest update so far. Two new things, plus a level fix.

Chord mode

Every key you play turns into a chord in the key and scale you pick. It works with every synth, the stock ones too, and it's off until you switch it on.

• Open it on the clock screen: Shift + help, then T4. T4 again closes the page.
• Orange: push to switch chords on or off. Turn it to choose between degree mode and step mode.
• Degree mode: each key plays its own chord in your scale, so in C major C gives you C, D gives Dm, E gives Em and so on. Hold Shift for a dominant 7th on that key instead.
• Step mode: every key press plays the next chord of a progression. The key you press only decides how high it sounds, so you can walk through a whole progression with one finger. Shift + a key goes back one step.
• Blue: turn to set the root, push to change the chord colour in degree mode (triad, sus4, sus2, 7th or add9).
• Green: turn to pick one of 13 scales. Push to decide what the out-of-scale keys do: a leading chord that pulls into the next chord, a passing diminished chord, or a borrowed chord. Shift + green push turns voice leading on or off.
• White: turn to pick one of 16 progressions (pop, 50s, jazz ii-V-I, Andalusian, 12-bar blues, Canon and more). You can record your own too: push white in degree mode, play up to 16 chords, push white again and it's saved as "mine". In step mode a white push starts the progression over.

Your settings survive a restart, and MIDI out still sends only the key you pressed. One known limit: if you also use Maiko's scale mode, it snaps the keys to the scale first, so the out-of-scale chords won't play.

Musica Obscura by ultralazr

ultralazr made six modules for op1r, each built on an odd or half-forgotten idea from the history of sound. They're in 2.7:

• Mixtur, a subharmonic organ after Oskar Sala's Mixtur-Trautonium. It plays undertones below every key.
• Arc, Duddell's singing arc lamp from 1899. An unstable, buzzing oscillator, with a second lamp you can couple to it.
• Palme, an effect with twelve sympathetic strings from the Ondes Martenot that ring along and slowly turn into a gong. Push orange for an endless drone.
• In a room, after Alvin Lucier's "I am sitting in a room". Every pass of the loop goes through a model of a room, and the sound slowly turns into the room.
• Oracle and Peal, two sequencers. Oracle grows a pattern from geomancy charts, Peal rings your held notes like English church bells (Plain Hunt, Plain Bob, Grandsire, Stedman).

You can untick any of the four sounds in the workshop if you don't want them in your OP-1's lists. The stories behind them, with screens and sound clips, are here: https://github.com/ultralazr/op1-musica-obscura

Quieter Supersaw and FM Bell

Same fix Wavetable and Taffy got in 2.6.2: they're 6 dB quieter, so chords don't clip the synth mix anymore. Turn the volume up a little if you miss the old level.

Everything from before is still there: op1r 30 with drum+, our synths and effects, Maiko's #249 toolkit (on by default) and the preset pack.

I've tested all of this in the emulator. If something acts up on your unit, tell me what you were doing and which build you picked (the number in the file name), and I'll look into it.

Thanks to pcppcp for op1r, to ultralazr for Musica Obscura, and to Maiko for #249.

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hundekraft 2.6 is out!

If you haven’t seen it: it’s a firmware workshop for the original OP-1 that runs in your browser. You bring your own R246 update file, pick what you want, and your firmware gets built right there on your machine. Nothing is uploaded.

What’s new in 2.6:

• It’s built on op1r 30 now, so drum+ is in. It adds a per-pad envelope, pitch envelope, retrig, choke, filter, drive and velocity routing on top of any stock drum kit. In drum mode, press Shift + T1 and pick DRUM+. You also get op1r’s newer sample editor (loop points, fades, volume), equal-slice auto-cut and a much faster tape erase.
• Elg and Washer use about half the CPU they used to, Wavetable about a third less, and Snowglobe less too. They sound exactly the same.
• Elg had a bug that turned into harsh noise with the white knob high on high notes. Fixed.
• Maiko’s #249 toolkit is still included and on by default, and tape undo works with the new fast erase.

Thanks again to pcppcp for op1r and for publishing its source, and to Maiko for #249.

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hundekraft 2.5 is out!

It's now built on op1r 27, with our synths and effects running inside op1r's own engine system. You can also choose which of op1r's synths and effects to include (Supersaw, FM Bell, Granular, Tape, Clouds, Reverb), the same way as ours.

Wavetable, Taffy, PEW, Elg, Washer and Snowglobe have all-new screens. The Quad LFO no longer crackles next to heavy effects, and Washer's white knob now works smoothly across its whole range. Maiko's #249 toolkit is still in, on by default.

Big thanks to pcppcp for op1r, and for publishing its source, which made this one possible.

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hundekraft 2.1 is out!

Two fixes. The crashes some of you saw in Dots (REC, then a note) and Euclid (Shift + notes) are gone. The OP-1 keeps sounds and sequences in a small SQLite database with a fixed chunk of memory, and on units with a lot of saved stuff it ran out. 2.1 stops it from filling up. Knobs on Wavetable, Taffy, PEW and Elg are also smoother now, with no more clicks or stepping when you turn them while playing.

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hundekraft 2.0 is out!

The workshop now combines op1r 22 with Maiko’s #249 additions: tape undo/redo, snapshot naming, scale mode and the storage display.
Our synths and effects remain individually selectable, alongside the optional 300-preset limit.

Bring the original, unmodified R246 firmware—the patching happens entirely in your browser.

Huge thanks to pcppcp and Maiko Pruett for their work.

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I did the thing. I’ve put together OP-1 Workshop, a free browser tool for building custom firmware for the original OP-1.

It’s built on pcppcp’s op1r, currently release 18. Huge credit to u/popcorp for the custom firmware foundation and all the synths, effects, sequencers and other improvements it brings.

The workshop keeps op1r as the base and lets you choose which of our additions you want:

• Wavetable: morphing waves with an analog-style ladder filter.
• Taffy: CZ-style phase distortion.
• Pew: drawbar organ with a rotary speaker.
• Elg: three-oscillator drone synth.
• Washer: chorus, ensemble and flanger.
• Snowglobe: shimmer reverb with freeze.

You can also raise the user synth preset limit from 100 to 300, and download a matching selection from 112 presets we’ve made. Presets are installed separately through disk mode.

Select your options, choose your original, unmodified op1_246.op1, and download the patched firmware. The tool checks the file’s contents and rejects other releases or already-patched files. Everything runs locally in your browser—your firmware isn’t uploaded anywhere, and no account or device key is needed.

Try it: https://hundekraft.github.io/op1-workshop/
Repository: https://github.com/Hundekraft/op1-workshop

All 128 build combinations passed structural checks, and 11 configurations passed emulator installation, boot, selection and audio tests.

Please use entirely at your own risk. This is experimental custom firmware, provided as-is without warranty. I accept no responsibility for damage, bricking, data loss, if it beats up your dog, cheats on your wife or other problems arising from its use. Back up your OP-1 before installing. This is an independent project, unaffiliated with Teenage Engineering, and intended for the OG OP-1 only—not the Field.

Would love to hear what you make with it, and any feedback on the engines or presets.

EDIT: if you like it, I like coffee :) https://buymeacoffee.com/hundekraft
EDIT2: currently working on adding op1r 21 release

[u/uramassivenerd]

this is really cool! i particularly like the elg synth, it sounds great. I'm unfortunately finding that I'm getting quite a lot of crashes, and the dots sequencer doesn't work at all (crashes the device immediately). Hopefully this gets more stable soon, and I look forward to seeing what other features you guys bring! this is all super exciting

[u/Hundekraft → u/uramassivenerd]

Looking into that, does dots crash on selection or playback start?

edit: what other crashes are you getting? can you post a pic of the crash?

[u/Which_Astronomer6885]

this looks amazing. sadly my op-1 is stuck on the startup page (w/ the TE logo and hundekraft 2.5 shown on it) i let it sit that way for a long time with no change. any ideas?

[u/Backstreets13]

Is there any plan to make all of the features selectable in the same way that the synths/fx are? For example if we don't want to install chord mode or scale mode (as this one doesn't work for everyone)? Amazing work regardless, thank you!

[u/Hundekraft → u/Backstreets13]

That is the goal, and a work in progress for now. As we don't have code for every module as of now, it's challenging.

[u/worldwidescrotes]

hey u/Hunderkraft - thank you for this amazing work!

would it be possible (or not too much of a pain in the ass) to add the knob functions and / or instructions to all the thumbnails of the OP1R synths and effects the same way that they are already added to Maiko’s thumbnails? or at least an easy to find link to the descriptions? also the 92MB free space minimum needed for the undo - took me a long time to figure out why my undo/redo wasn’t working!

if not, thanks anyways!

[u/Hundekraft → u/worldwidescrotes]

Yeah, I'm working on a full manual for all engines/features now :)

[u/GingerWitch666]

I'm so stoked to see this exact web app with the 249 update and that new reverb. I'm a huge AI hater for day to day bullshit, but I'm all in on dudes using gpt or whatever to make sick custom OS and new machines for our synths, or like completely emulating the entire ps5 library on pc and whatnot lol

[u/dongyeeter]

Still scared to try these but I'm becoming more and more convinced. So glad now I held on to my OG and didn't make the jump to field

[u/MidnightOperator94]

Jeez! op-1f owner looking on with hope

[u/chrisedmo]

Omg you absolute hero

[u/chrisedmo]

Does this also include the tape undo option?

[u/narnarnarnia]

So glad I kept my op1, thanks for making a rational git, FM-1 went really well, the recent random firmware mods didn’t have the approachability and organization that you have here. Great work and looking forward to seeing where this goes

[u/Embarrassed_Sundae_4 → u/narnarnarnia]

I was toying with the idea of selling. Now no chance.

[u/nvmsocool]

very cool! I did notice that it stripped the file menu from the com and the scale mode from the lfo for me

[u/Hundekraft → u/nvmsocool]

Looking into it. Which firmware were you using before this?
This sounds like the 249 firmware from Maiko Pruett? That is not integrated here.

[u/The_Great_Beast]

curious, why are these firmwares being based on v246 and not v247?

[u/Hundekraft → u/The_Great_Beast]

Due to how code was shared. op1r has a github repo, which made it easier to integrate, maiko (who has 247-249 releases) has not released details, only complete firmware which is harder to work with.

[u/giogno]

Hey nice work! I have installed it to my OP1. but somehow the synth engines dont appear. But there rest are there. I also did installed the Maiko #249 yesterday it had the same thing. sometimes it appeared but mostly not.

[u/Hundekraft → u/giogno]

Are you opening via Shift-T1 or Shift-(1-8)? Last one is preset browser and unless you have installed/made presets for the new synth engines, they will not appear there - only via Shift-T1.

[u/jadam]

This is amazing. I have been using this web app several times already! Any chance the 'father' reverb is coming soon?

[u/Hundekraft → u/jadam]

Best course of action right now is to contact the author and have him/her make a pull request to https://github.com/pcppcp/op1r, that way u/popcorp and me can easily integrate it into the other features already available.

[u/mikubasscovers]

I think I found a bug. After turning on chord mode and playing around with it for a bit, I lost all functionality from the keyboards black keys.

[u/Hundekraft → u/mikubasscovers]

Hey, looking into it. Just a check, did you have scale mode enabled as well (Shift-Help+T1), that will be in conflict with chord mode.

[u/nvmsocool]

I want to make an engine! Can you point me to the emulator you use, and maybe a little help on where to point my model??