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Molten Modular Motion Meter

Molten Motion Meter

Here at SOS, we pride ourselves on an unbiased approach to reviews, treating all developers with equal respect, big or small, new or established. Many of them we know personally, many we don’t. But I’ve never had something pass across my desk from quite as close to home as the Molten Motion Meter, since it was developed by our very own Robin Vincent; a core contributor in this here modular corner of the magazine, as well as to Sound On Sound at large. Molten Modular is the name under which Robin has recorded his foray into Eurorack online, featuring a host of rather excellent videos, a newsletter and now a burgeoning line of brand‑new modules. It’s well worth checking out his website ( and accompanying YouTube channel, particularly if you like jazzy shirts.

The Molten Motion Meter is the fruit of a collaboration between Robin and DIY‑leaning Eurorack company Befaco. Available either assembled or in kit form, it came about in response to what Robin calls “my desire to be able to visualise modulation... to be able to better connect visually and aurally to what the heck was going on with the modulation and signals in my patch.”

So what is the Motion Meter? Well, it can be a lot of things. Its cute 6HP panel presents three knobs, each surrounded by a halo of LEDs. Each of these has its own input, output and accompanying three‑way mode switch with options for Audio, CV Attenuation and CV Inversion. With its three outputs able to mix down to Output 3, it can also act as a simple mixer, with some handy three‑colour visual metering to boot. I’ll also say I was pleased to find that at full tilt in Audio Mode it’s actually able to drive sounds a little into what sounded to me like clipping distortion, which you may like or hate, depending on your persuasion. Switch to CV Attenuation and the LEDs around the knob in question turn purple. With nothing patched to that channel’s input, it outputs a static 10V at maximum, suiting it well to acting as a remote control for another less reachable or less visually intuitive module during live performance. Even simply using it to open a filter is satisfying, with that accompanying ring of purple LEDs. Patch any CV into that channel’s input and the LEDs will meter the motion (geddit?) of the incoming signal, and the knob becomes a useful offset.

Set a channel’s switch to CV Inversion and its respective LEDs turn amber, metering anti‑clockwise around the knob instead of clockwise, which is a nice touch. This is where the Motion Meter becomes a lot more creative, since it can invert any signal thrown at it and completely change the character of a signal — even a patch — at the flick of a switch. With nothing patched to Outputs 1 and 2, Output 3 will sum their values. This makes for some great modulation possibilities: set one to attenuate and the other to invert, for example, and work the two against one another. I particularly enjoyed routing the main body of a simple patch through the Motion Meter to control every aspect of it. Through Channel 1, a VCO; through Channel 2, CV from a sequencer to that VCO; and through Channel 3, an envelope going to that VCO’s wavefolder. This way I could adjust the volume of my oscillator, attenuate its pitch and adjust the amount of wavefolding all from a single panel. Classy!

If there’s one criticism I could throw at the Motion Meter, it’s that it would benefit hugely from CV inputs for each channel’s parameter position. On one or two occasions I found myself wishing I could have the knobs’ values move by themselves, or at other times to move faster than one could turn the knob manually. Apart from anything else, this would also essentially render it a fully functional three‑channel VCA on top of all its other functions, which would be tremendously useful. That said, I respect the way that the Motion Meter encourages — even demands — hands‑on performance, and this is much of its identity at the end of the day. One assumes it needed to go one way or the other: patchable and socket‑heavy, or big, beautiful knobs and LEDs. Clearly the latter won the day, and as it is there’s not much to complain about.

The Motion Meter is a great example of what I think of as an ‘enabler’ module, expanding the functionality of all the modules around it...

The Motion Meter is also available in a recently released 1U version, which offers four channels over the original three. This is a good move, with that extra channel opening up a lot more combination opportunities — particularly when it comes to working with stereo signals. Whichever version speaks to you, the Motion Meter is a great example of what I think of as an ‘enabler’ module, expanding the functionality of all the modules around it and so open‑ended as to only be limited by one’s own lateral thinking. This functionality would expand exponentially with more than one in your case, which I can totally imagine having since it’s so widely applicable, and I’ll submit it’s just about affordable enough to warrant repeat purchases. Bravo, Robin.