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Introducing Roucha Legio


It’s always a good day when we have a new module to explore. And today, we’re taking a look at a module that a lot of you have requested: a filter for the Legio platform! 

Roucha Legio is a whole lot of fun: it’ll do all the things you’d expect a filter to, and it has a few tricks up its sleeve, too. Legio paneled as Roucha Legio modules are shipping now as are replacement panels and hotswappable overlays, and if you’re already a Legio owner you can, as usual, try out the Roucha firmware completely free at the Noise Engineering Customer Portal.

Roucha Legio, stereo multimode filter by Noise Engineering

A multimode filter and more 

Roucha Legio has modes for lowpass, bandpass, and highpass filtering. It’s a stereo 12dB-per-octave filter, so as well as being an excellent tool for mono subtractive patches, it sounds great on samples and other stereo sources. We’re big fans of live-performance patching here, so we also added a bypass option so it can be used like a DJ filter: run your whole mix through Roucha, turn up the filter cutoff to create a buildup, then tap the Frequency control to bypass all processing and bring your whole mix back instantly.

Resonance and wavefolding 

No filter is complete without some resonance, and Roucha’s resonance is all that, and then some. With no resonance the filter is quite clean, but it goes into wild and screamy territory when cranked to max. I’m a big fan of using characterful filters like this at maximum resonance to create distinctive timbres – here’s an example of Roucha filtering a couple of saw waves to create a big, brassy tone.

Roucha has a unique input architecture that was designed to reduce noise when used over a full mix. A nice side effect of this part of the design is that it won’t start oscillating until it’s excited by something at its input: this makes it easy to experiment with, and it won’t start singing by itself unless you want it to. 

One feature we add to of a lot of our oscillators is the wavefolder: it’s a classic technique that adds a lot of  character to a sound. We decided it would be a perfect addition to the Roucha filter, too, and along with the normal Fold amount parameter, we added a switch that places the folder before, after, or both before and after the filter. Double the wavefolding, double the fun!  

This is only the second time the distinctive Noise Engineering wavefolder has been featured in an effects module, and if you’d like to use it in isolation (and in stereo!) on a sound, Roucha makes it simple. Just open up the filter all the way, turn down the resonance, and you have a voltage-controlled wavefolder that you can put on top of any sound you’d like. 

On of my favorite things to do with Roucha is to use it as a voice on its own: by sending a short trigger to the audio input and tweaking the Resonance and Fold settings to taste, a lovely pluck comes out that’s the perfect lead for a melody or arpeggio. Filter pinging is a fun synthesis technique to play with, and the Fold parameter adds an extra layer of character on top of the usual pings and pops. 


Along with the above patches, you can find a number of fun patch suggestions in the Patch Tutorial section of the user manual.

The long road to a stereo filter 

The development process for Roucha didn’t actually start with the goal of creating a filter. We knew we wanted to make a filter at some point, but we had a set of concept firmwares that were relatively far into development, and we figured that with some arguing and tweaking we’d the next product concept, so we’d refine one of those existing firmwares. 

That didn’t happen. After weeks of design, development, testing, arguing, and tweaking, we just didn’t could not get a consensus agreement on any of the firmwares we had. Stephen mentioned that, as a last resort, we could look at a filter firmware he’d recently rediscovered, after it had been left on the backburner a few months prior. As soon as we tried it, we all loved it. We added a wavefolder because wavefolders are awesome, did some final tweaking and we finally had a new addition to the Legio family. 

The final step of the design was to come up with a name. At this point, we just wanted to get the filter out the door and when Stephen suggested we call it Roucha, meaning pants, because, “it has a wavefolder and you fold laundry,” we agreed without much hesitation. After a quick clarification on spelling and pronunciation (a Groucho Legio panel, complete with mustache and glasses, may have been presented as an early art concept) we were ready to share Roucha Legio with the world. 

Don’t forget: if you have a Legio already, you can try out the Roucha firmware on our Customer Portal and pickup an impact acrylic overlay. Or, order a complete Roucha Legio module from your favorite retailer or our webshop

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