Module Review: Qu-bit - Aurora


Probably like many others, the first time I encountered FFT, was the Paulstretch program. I was curious about production techniques used in dark ambient, like in the mixes put out by Cryo Chamber. There’s an long article interviewing a load of dark ambient artists about their methods, but while there’s a range of diverse and interesting music within what one would categorise as Dark Ambient, I was particularly curious about how a consistently-appearing sound was achieved in many of the long-form youtube mixes- the kinda hazy low-mid soundscape that’s hard to describe as anything other than “atmosphere” or “ambience”.

This is where Paulstretch comes in. An FFT-based Open-Source program released by Paul Nascar in 2006 that takes samples and slows them down a load with various controls over how the audio is affected in the process. If you put something clean sounding and melodic in, then what you get out is likely to sound fairly pleasant, whereas if you put in some spoken word or random field recordings, then you’re going to get something more unpredictable and hopefully demonic sounding out the other end of it. The results are often instant, atmospheric, kinda creepy and exactly the sound I was curious about. Paulstretch is also available as a free VST for all platforms and a basic version is one of the included effects in Audacity.

Now as a layperson, in regard to how this FFT business works, I feel like I understand to a point, I’ve watched some videos about it and it’s super interesting but quickly gets into a lot of advanced maths stuff that goes way beyond my understanding. Just putting that in here because i’m bound to have described the technicalities of it incorrectly at some point. From what I understand though, (and i’ve probably plagiarised this from the Aurora manual) the idea is that you use the Fast Fourier Transform algorithm to convert audio into a bunch of sine waves, which then allows you to alter the time and frequency independently of each other. In practice this basically means you can take any sound and stretch it out into long, interesting textures while maintaining the original pitch, or modulating it as you see fit.

When it comes to Eurorack, the most well known implementation is probably the Spectral Madness alternative mode on Mutable Instruments Clouds, which interestingly was initially intended to be the main function of Clouds. The latency involved in FFT processing, because the processor needs to analyse the sound before it can mess it up and give it back to you, was the main barrier to it featuring a lot in Eurorack. There are a couple of old threads on Modwiggler discussing FFT-based and similar effect modules. If you’ve got a Clouds, μClouds, Monsoon or whatever, and you’ve never braved the Spectral Madness mode, I highly recommend you check it out.

Now we jump forward to May 2022 and Qu-Bit’s release of Aurora- a “spectral reverb” using the FFT algorithm. It can also run alternative firmware, powered by Electrosmith’s Daisy platform (which is also used in Noise Engineering’s Versio modules). I would guess that Aurora is made possible, despite the previous limitations of implementing FFT-based effects in Eurorack, partly because of the power of the Daisy platform, and partly because it’s just designed in a different way, to work with the latency issues. Aurora does have some latency between the dry sound and the wet sound, but definitely not in any way that’s been noticeable in my uses and it does have the option to delay the dry signal if you want zero-latency, like if you’re using the effect on percussion.

Aurora has stereo in and out with controls over pitch (Warp), time, delay (Reflect), blurring and atmosphere (some magical filter business). The LED interface, besides looking awesome, is especially useful as it move through different colours giving feedback on parameters and is also helpful for navigating to octaves and factory settings. The USB port on the front makes it really easy to change firmware or adjust some of the deeper settings.

This is the video that sold it to me and the official video guide is also worth a watch if you’re not sure whether the module is for you. I was hyped at the thought of being able to bring the aforementioned "atmosphere" sound into Eurorack; I’ve always been looking for a module just for processing field recordings and turning them into interesting soundscapes (admittedly mostly recordings of the rain or household objects rather than audio captured from some exciting expedition).

One of the first things I did was run through the patch examples in manual. This was really helpful to understand different potential uses but also helps hear the effect of modulation sources and the different characters of the 4 FFT size settings- which is basically like the resolution and changes the sound quite a lot, particularly when modulating the Atmosphere parameter. It definitely feels like a module that benefits from time watching the videos and reading the manual- I wouldn’t say it’s a complicated module to use, but it takes a bit of understanding of the parameters to dial in the sounds you want. The fact that it’s perhaps less instantly gratifying, actually makes it more exciting because there’s a sense of exploration; it’s taken me 2 months to write this review because I wanted to take the time to really get my head around it and test it in different situations but I’ve loved every minute of it.

Like most modules that excel at turning audio into interesting textures or long smooshy sounds- what you put in has a massive effect on what it spits out. A cleaner input will be more predictable, while more complex sounds take a bit more experimenting to get used to what the results will be. Holding shift and turning the mix knob allows you to adjust the input gain which is really handy as the volume of samples seems to have a big difference on the outcome and this feature also allows you to run gear into it from outside the rack.

On melodic parts, it sounds great. You get a nice shimmer if you raise the pitch an octave or two and a unique range of effects as you mess with the time setting. If you send shorter sounds through and randomly modulate the parameters you can quickly get some pretty weird, unhinged noises which I love. For my main use case of wanting to create longer dark atmospheres, it works perfectly and I can’t wait to experiment more with different samples.

You can dial in something closer to a more typical reverb sound but I think because of how much fun it is to move away from that and get weirder with it, that it’s nice to have another reverb after it. In my case I run it straight into Desmodus Versio so that I can overdose on gloomy atmosphere. For more traditional reverb, Qu-bit have recently released the first alternative firmware, the FDN Verb - I haven’t got round to trying it out yet, but it sounds super cool from the demos.

To summarise- Aurora is an awesome, versatile audio to dark ambient atmosphere machine, with mesmerising glowing lights, that’s pure joy to use. With alternate firmwares and easily customisable settings available via the USB, it’s a deep module with a lot to explore without being overly complex. My recommendation is to pair it with Desmodus Versio, test all the different uses and have a great time.

You can grab one direct from Qu-Bit or support your local synth shop.

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