WhatTheRack: a Rack randomizer

VCV Rack is a great emulator of Eurorack synths. But it’s missing one great part of modular synthesis: puzzling over someone else’s rack and figuring out what these unknown modules are, or why they have 5 sequencers but a single VCO. Sometimes, too, software gets in the way of creativity: it’s just too easy to add 10 more VCAs, or to duplicate that module you enjoy so much. Hardware doesn’t allow that, and these constraints can sometimes be the source of very creative patches.

WhatTheRack offers a solution! Hit the button, and get two dozen random modules, including a healthy mix of VCOs, LFOs, effects, filters, mixers, sequencers and more, guaranteed to fuel your next jamming session. The module scans through your installed modules, picks some for each category (2 VCOs, 2 LFOs, 1 mixer, etc.) and spawns them in your rack with randomized parameters. Patch and see what happens! Just like the first time you played with a modular synth.

I started this as a joke, and it mostly still is one, but as I developped this today I got some great surprises. Turns out, I have a zillion modules I never tried, and some are really cool. Without this random chance, I would never have tried them. And it was fun to go back to my first impressions of modular synthesis, i.e. “what the hell is this mess in front of me”.

I’m sure people with more talent than me will actually make good music with randomized racks too, so I’m excited to release this and see what happens. Sources are at https://github.com/korfuri/WhatTheRack. Enjoy!


do you have a compiled win version? (couldn’t find it on github)
I would like to try it.

Interesting, here’s windows dist.

WhatTheRack-0.6.0-win.zip (419.2 KB)

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Mac please?

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very nice idea! but everytime when I tap the “?” it adds the same plugin set!

I just tried and I have the same set of plugins everytime I first click the “?”.

If I re-click new set is added to the previous and it is different,


it is the same “2nd” set of modules everytime I had a 2nd set.

etc, etc…

Can confirm this is also happening for me. Every time you open rack or start a new patch the first, second, third, fourth etc/etc… set of modules added are the same.

Perhaps another approach would be to first have different buttons for module tags one button adds random LFO(s) another VCO(s) but also randomise the randomness.

I also tried initializing and randomizing the module in the context menu, just in case it would have change something :smiley:

but no :frowning: same result

I had to try :stuck_out_tongue:

How do I build this on linux? I’ve cloned the repo and if I ‘make’ I just get

Makefile:29: …/…/plugin.mk: No such file or directory
make: *** No rule to make target ‘…/…/plugin.mk’. Stop.

i’m 100% the target audience for this. keep us updated on RNG fixes!


I’ve fixed the randomness issue, I think. I’m not able to reproduce it, but I suspect it has to do with how the RNG works on different platforms.

Unfortunately I’m not able to build for anything other than Linux at the moment. Someone else will have to build for Win and Mac. Here’s a build for Linux: WhatTheRack-0.6.1-lin.zip (415.3 KB)

@TroubledMind, to build, you’ll need the Rack-SDK. Git clone WhatTheRack like any other plugin under Rack-SDK/plugins/WhatTheRack and make from that directory. Or make RACK_DIR=path/to/Rack-source if you have Rack 0.6’s sources cloned somewhere already.

Thanks for the feedback on usability. I’ll look into making this a bit more customizable :slight_smile:

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WhatTheRack-0.6.1-mac.zip (1.1 MB)



Fantastic! Works as it should now.
Found a new module thats interesting for me after seconds. The only thing the module should have is a crease button for every module beside of the WhatTheRack module. Because for a new start you have to erase all and reload the WhatTheRack module.
Thank you for this idea!

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WhatTheRack-0.6.1-win.zip (419.2 KB)


Great idea! Look forward to playing with it.

@korfuri not sure if this is intentional maybe so, but I noticed your question_bw button is not showing as one might expect (same size as question_color). Looking into the svg I see that it is much larger than button_0 (512 x 512)


Thank you very much!

Works perfectly now, thanks for the quick fix.

Really great idea !!! Thanks
I have to test this tonight