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Cosmotronic Cosmix Pro

Eurorack Module By William Stokes
Published June 2023

Cosmotronic Cosmix Pro Eurorack module.

We live in a world of component shortages and economic uncertainty, where boutique developers are often found on the front line in the fight for survival and must therefore make every design count. Dutch developer Cosmotronic — aka the one‑man operation of Matthijs Munnik — has relatively few modules on the market yet maintains a laudable strike rate, with a focused range of designs bridging the gap between reliable and innovative with aplomb. The Cosmix Aural Enhancing Stereo Mixer was one module that certainly fit this description, now discontinued due to a lack of components for its much‑loved dual‑band distortion circuit. This led Matthijs to a fork in the road: double down on the Cosmix and find alternative components to try and recreate it, or make lemons into lemonade and go in another direction entirely? Thankfully for us, he opted for the latter: the Cosmix Pro is an eight‑channel mixer offering a broad range of routing possibilities, with generous amounts of visual clarity and several functions usually reserved for much larger mixers.

In a sense, the Cosmix Pro toes the line perfectly between an upgrade and a lateral shift; by this I mean it can be paired with the Cosmix via a rear Link cable, so even if you’re an owner of its predecessor there’s something for you here. It has 6HP on the width of the Cosmix, and while it offers the same amount of inputs, not only does it do more with them, its spacious layout feels clearer, faster and, well, more like a ‘real’ mixer — hard as that notion is to qualify.

The Cosmix Pro’s panel presents a total of six channels, constituting four mono and two stereo channels. Each of these has a dedicated slider and miniature three‑colour VU meter, as well as a large mute button and a pan pot. A master level knob sits on the bottom right of the module beneath a pair of master meters. So far so solid. The mute buttons are brilliantly designed: clickless and brightly lit, they are as well suited for bringing parts in and out of a performance in a low‑light setting as you’ll find in a Eurorack module. They also engage on release and not on contact, meaning it’s easier to bring things in and out right on cue. Beyond this is where things get a little more interesting — or, should I say, ‘pro’. The first four channels each offer a low‑cut switch, which applies a tasteful 1‑pole high‑pass filter at 80Hz. Very useful for staving off low‑frequency build up in a patch, particularly if you have a few low‑pass filters on the go. The two stereo channels, meanwhile, each have a gain switch to boost their respective incoming signals by 18dB; in other words, to bring anything line‑level up to modular level. This immediately opens up the Pro to the world outside of your system, unifying it with anything from samplers to laptops to centralise your setup, on stage or in the studio.

Where the original Cosmix had one mono aux send, not only does the Pro boast two sends, but one of them is in stereo. Now luscious stereo reverbs or ping‑ponging delays can be applied to any input signal, mono or stereo, leaving the mono aux free for things like feeding a side‑chain input on a compressor, to name but one possibility. The mono aux 1 is reserved for the first four channels, while aux 2 is available for all six. Capping it all off are two CV inputs for the panning on stereo channels five and six, whose pan pots become stereo balance controls when both sides are connected, opening up some interesting opportunities for movement across the stereo image.

There are one or two things I’d have loved to see on the Cosmix Pro, for instance pre‑fader aux sends, or at least the option to set them so. I’m the kind of person who keeps my aux sends permanently set to pre‑fader, which not only gives me more flexibility with the wet/dry balance on my effects sends but also allows me to use the auxes as alternative outputs for certain channels if needed. While the Cosmix Pro’s sends are unalterably set at post‑fader level, I should say that with its generous amounts of headroom across the board, with my main channel fader low and aux level turned up high, I wasn’t far off being able to hear my effects fully wet. I would also have appreciated a headphone output, which doesn’t feel like a stretch considering the Cosmix Pro definitely has the panel space. I’ve seen the question of quarter‑inch outputs asked elsewhere, but I believe mini‑jack is the right call for any Eurorack mixer; not least because it lets you easily feed the main output into other modules.

At the end of the day, to adapt GK Chesterton’s well known adage: mixers, like art, consist of drawing the line somewhere. One could go on forever thinking up potential features — inserts, EQ, polarity buttons and more — but this would be inappropriate. Ultimately, a Eurorack mixer has to be selective with its functions, otherwise you may as well just get a standalone mixer. The Cosmix Pro has chosen well. It’s sleek, it’s smart, it’s reliable, it’s creative (it’s also very cute), and suffice to say I’m now struggling to imagine my system without it.