Orac : open source instrument thing ;)


Its a wild ride for me today, as Im releasing Orac, an open source, free modular instrument Ive been working on for a while :slight_smile:

Its been released today for the Organelle, however, its not Organelle specific at all, in fact I already have it running on the Raspberry PI (rPI) and Bela Salt (in a eurorack) as well.

I thought Id post a few details here, first the concept (for musicians) and then a bit more technical stuff… for those that might be interested.

here is a video , that explains what it is better than I can :slight_smile: (thanks to loopop)

anyway, the basic idea behind Orac was simple…

There are some great new hardware platforms, that are cheap and powerful like the rPI, and I wanted a way to use them musically, to take them out of the desk draw they get stuffed in…
I liked the idea that something like Pure Data could be used to create synths/fx/sequencers quickly, that could run on the rPI.

But I found once I did this, that everything was a bit fragmented (even on the Organelle which is well organised), sure you can get some great patches, but how do I link them to midi , how do I save/recall presets, how do I combine them… and the only answer was start doing (lots of) patching in Pure Data.

what I wanted was a way to do these things, without patching, and to have some consistency

So… I decided to write it, and so we have Orac.

a modular synth, that uses pure data for its modules, but allows musicians to select modules, do midi learn, save/load presets, remote control from OSC and much more.

it comes with over 50 modules, including adaptations of some wonderful C&G patches, to ports of mutable instrument modules.

obviously with a headless (or small display) , we are not going to patch via wires, instead in Orac I created ‘Router modules’ , these describe how to route audio, notes, mixing etc.
these, I guess are similar to the DX7 algorithms , though Orac allows new ones to be added.

thats it really, the idea is to leverage the easy of use of pure data for module patchers, but to hide this from musicians to just let them combine things and control things as they want.

today, its out on Organelle.

for the rPI and Bela Salt, currently I can configure and control these by using a Push 2, taking a config from Organelle, or editing a config file.

this is obviously not the end goal, as its not suitable for many musicians…

so the next goal is to add a web app, such that users can control and configure if from their phone/ipad.
(of course once the rack is setup, they are then free to disconnect this, and control the rack from midi - it is designed to be used ‘headless’)

if you are an open source developer, especially if you have experience on web apps - Id love to hear from you, it will speed up this process a bit, and mean I can get it to rPI and Bela users asap.

so lets get a bit technical , as I think some here would like this…

another goal for me, was to make module development simple, as i noticed i spent a lot of patch development time on the UI, presets, midi … all things a framework could do, to remove the burden from the module developer.

so I developed the framework in C++ , which basically is an API that broadcasts parameters locally, and via OSC (for remote control)… also supports other ‘control messages’ e.g. midi assign.

This framework , also then includes a pure data externals, which do most of the work, the user simply includes the KontrolModule file, and then presents it with a module definition file (json) which describes the parameters.

some ‘interesting’ tech facts:

  • Orac actually dynamically re-patches the main patch in C+ from the main KontrolRack external :slight_smile:
  • Routing is done via routing modules, which are also written in PD, so anyone can add new routing schemes

of course, using pure data, osc, its all cross-platform… so much of the time ive been developing/converting modules on my mac, using the Push 2 as the display/control, and then just download it to the Organelle/PI/Bela to use/test it :slight_smile:

as I said already, the next step is to add a ‘browser’ implementation, that way anyone with a raspberry PI sitting in their desk drawer can find a use for it.

Bela Salt … this is quite fun, having a virtual modular in a eurorack case is quite ‘meta’, but also means that there are quite a few other options for modules e.g. Orac can be a midi to CV converter , CV modulator, and also rather than always using it as stereo, you can treat the 2 audio channels independently, so basically use the module as 2 audio modules (and still do cv output too)
(Orac supports a concept of chains, which is like multiple tracks)

anyway, thats what Ive been up to recently… I really enjoy it on the Organelle, and I can’t wait to get it out on the rPI and Bela for others to enjoy it too.

anyway, I hope this is interesting… if you have any questions id be happy to discuss,
and its open source, so if others are interested in participating again id love to hear.

(I’ll post the link later today, I just need to move it from my private repo to the public one, now its released :slight_smile: )


Cool stuff! I think you do well thinking about a web app. I don’t think making the patches on a tiny screen like the organelle’s is going to be really fun on the long run (though it’s great to have that option when you want to change things on the fly!).
I quite like how you can organize things via the web app in MODED / MOD DUO, albeit making the whole headless thing only half as useful to me (but that’s another story and specific to how I have things set up).
Are you also considering to make a pre-configed rPI image for this? Something like MODEP where you can just burn the image onto an SD and just plug&play?
The Raspberry+Pisound combo is great, but honestly… it can be so laborious and frustrating to get things to actually work, and so far, nothing has really worked for me, with endless hours wasted on trying, which would have been much better spent making music.

Edit: Just to be clear, considering this is an open source project, and that I have no idea how much work is involved in making such an image, I can totally understand it, if this is not something you are planning to do.


Super clean and elegant, no hardware restarts or software recompiles during the whole process. I don’t have an Organelle, but sweet!!


actually its not too bad on the organelle screen, as you dont need to do the routing, so its just selecting things into ‘chains’, then adjust parameters, its all pretty quick.
also, the modules we are talking about are high level, things like sequencers , synths etc - so your getting quite big chunks of functionality per click :wink:

though, of course for performance, that would be tiresome - which is why midi learn is fully integrated.

my guess/hope is for a similar experience to the OP-1,
though of course the focus of this is very different, this is about an (easy) extendable platform, something that can grow from the community.

Are you also considering to make a pre-configed rPI image for this?

Im already talking to blokas, so thats a definite possibility.
they already use an image builder to create modep, so its just a matter of cloning that and switching the application… but yeah, that would come once Ive the UI for the rPI.

another option, and not mutually exclusive, is to put a touch screen application on the rPI, as quite a few have touchscreen on PI - but thats after the web app.
oh, and these new UIs, of course, will all work on the Organelle and Bela too :wink:

on a separate note, again Id like to thank Mutable Instruments and also C&G for open sourcing their code, this project really stand on their shoulders.

one thing, thats perhaps not clear here, is alot of the modules are derived from C&Gs patches, and if you don’t know C&G, you will be in for a pleasant surprise - C&G have a rather different / playful outlook, and this really comes across in things like their sequencers.
Their sequencers are really fun to play with in a Eurorack context :slight_smile:


Sounds really great and promising! Thanks a lot for this!
Btw. another question, to get the Pd patches into Orac I guess you’d all copy them into a folder, but you’ll probably have to also prepare them in a specific way, or how does that work?


lovely. also: as someone whose naming strategy for computers is “naming them after fictional computers”: good name. (My last computer was called Orac).


if you see my ‘creating modules’ video, this shows how modules interact with Orac, its deliberately very simple.
then yes, they get put into the modules sub-folder.
(for the Organelle, the new ones can added via an install package, but thats kind of ‘sugar’ )

at least initially, I suspect they will be shared on patchstorage.com, as thats where many Organelle patches are already shared.

btw: heres the current module list , all working on organelle, pi and bela
module list


So cool! :exploding_head: – The ‘it can be anything’ idea of the organelle is coming to life in a way where makes sense in practice. Super amazing news!!!


Quite a list!
I’ll check the video as well, thanks for the heads up! (I was this post after the one on blokas.io and didn’t kind of register that second video)


I have to say, I’m no programmer (a ‘modifier’) but the Organelle has really over-delivered in my expectations. Thanks for yet another amazing box of possibilities. :zap:


I’m impressed. having on the fly patch edit capabilities, as on on aleph or er301, is a huge win.
even when I share some concerns about usability (also on aleph btw), it’s a very very nice thing to have. as someone who is less likely to focus on pd, this is specially appealing to me.

you’re really on fire and don’t fail to better every time. many many thanks for your work sir!


This looks like a well-considered set of concepts to introduce into the rapidly mutating “music appliance” space, and a big win for open source. Congratulations.

I look forward to the “orac on / off” synthesis module:

Blake’s 7 is my all-time favorite SF TV series, if you don’t count The Prisoner. I ran a record label called Orac from 2000–2010: https://www.discogs.com/label/5208-Orac-Records


thanks @randy

Blake’s 7, a favourite of mine too.
Orac’s character was great, and very typical of BBC SciFi props/sound effects at the time, no expense spared :wink:


a very good question on C&G forum (from Andy, not sure if he is here at lines), which I thought others might be interested in. (important because PD is single threaded)


one word: Thanks! (ad libitum) :slightly_smiling_face:


i have a set of pd patches that i think i am going to try to convert to this. it was made with a similar idea that folks who bought the organelle most of the time did not want to learn pd which disappoints me but i think it also will make a bunch of the users who just want to make this go with that without having to deal with menus – which is my least favorite part of the organelle stuff too.

i have about 30 S- sounds/F effects & i guess M -modulations/Math functions based on Roman haefeli’s NetPd Set of tools that i think will work and were kind of intended to emulate the Empress Zoia box that i think is coming out soon too


Another rabbit hole! @TheTechnobear thank you very much indeed :slight_smile:


Looks very immediate to use with the Organelle and very interesting as a coding project - congrats on the nice work!

Also makes me want to blow the dust off my rPi :-).


I wonder could the (upcoming?) norns web editor be repurposed for use with pisound/organelle/orac?


Just grafted this onto my Organelle and wow, this has really upped the dimensions this little guy can perceive! Thanks for all the hard work (I know you had fun doing it).