In the real world, a twenty-four page tome explaining the reasons why it's necessary to sharpen your skates or get new brake pads would go mostly unheralded and unheeded. Lucky for us—and even luckier for synth manual readers and writers—synth enthusiasts are a pretty curious bunch by and large: We be readers, if you will, and a two dozen page deep dive into the mechanics, reasoning, and mathematics of the properties of momentum can actually be thought of as interesting, inspiring, educational, potentially musical, and even important. What other subset of anything has fervent collectors of instructional manuals?
Evan Buswell of New Systems Instruments is an obvious wordsmith and enthusiastic reader. Even name-dropping the 5th century BC philosopher Zeno of Elea and Achilles in NSI's manual for their new module, Inertia, couldn't scare me off from reading the whole thing—though it was damn close. Evan's scholarly work made for a good read on a rainy Saturday night in the pitch black 4 PM of a Seattle winter evening, though I can't say I dove too deep in the math department. Still, it's a good enough testament that if you have kids of a certain age trying to get out of studying math by saying that algebra and the like are a waste of time, not applicable in the real world, you can produce a convincing counter-argument: "Ah! Not so!" you can say, while you regale them with the kinda real-world mathematical applications from the Inertia manual.
If you don't have time for a good read, or any free dark and dismal Saturday nights, but are still interested in both inertia and Inertia, then by all means, read on.
Inertia is a module inspired by the holy grail of function generators, that being Serge’s DUSG, and makes no bones about it, but what separates this module from the others with the same inspiration—aside from the lengthy manual—is in the name itself: Inertia. Basically, as the Blood, Sweat & Tears song says, “What Goes Up, Must Come Down,” and when it comes to sound waves, this holds very true. NSI, however, has decided that adding a little momentum to each the RISE and FALL of its signals can delay that “going up” and “coming down” bit, and by doing so, has opened up a whole new world. In other words, don’t sharpen those skates or get new brake pads [actually, please do]. Instead, embrace this overarching movement, this imprecision and possible recklessness, this momentum. See where it leads.
Inertia has two modes that are switchable via toggle, RISE/FALL mode and SKEW mode. Every control on Inertia has two functions, depending on which mode you’re in, and this is indicated by the text being orange when in RISE/FALL mode and blue for SKEW mode. As for those controls, they are RISE/FREQ and FALL/SKEW, grouped together as RATE, RISE/MOMENT, and FALL/SKEW, which are grouped together as MOMENTUM. Each of these controls has a CV in with attenuverting capabilities. There’s only one other control, another RANGE toggle, that switches between low and high audio range. As for ins and outs, there is an INPUT, a rising edge TRIGGER input, a 1V/o input, and two outputs; a FIRST ORDER OUTPUT and a SECOND ORDER output, both with an LED level indicator. It’s a really unfussy and simple layout, belying its potential for complex and unique operation.
Inertia allows you to control rising and falling rates—like most EGs—but adds some special sauce in the way of momentum. Since the momentum of the RISE and FALL can be controlled separately, that means the signal can overshoot its starting and ending point before attempting to make its way home, sometimes unsuccessfully. Because of this, Inertia can be used as a VCO, a resonant filter, an envelope generator, an LFO, and on and on. For the most part, all of Inertia’s controls and parameters are pretty self-explanatory, though I’m not sure everyone will be familiar with the terms first and second order, which the manual, unsurprisingly, does a very thorough job of spelling out via graphs and text. It’s pretty interesting. From a short gist via the manual:
“In Inertia, first order exponential motion follows some target input, whereas second order exponential motion follows first order exponential motion, which then follows some input.”
What this means is that, for example, when using Inertia as a filter, FIRST ORDER will take on a -6dB/oct slope, while SECOND ORDER will take on a -12dB/oct slope because of its relationship to FIRST ORDER—it lags behind it. While I was familiar with what exponential movement/motion is/was, I hadn’t known mathematically how that was represented until I read about it in the manual.
While Inertia is one of those modules that can do a lot of different things, I normally shrug off using a module like this as an oscillator as there doesn’t seem to be much point. I’ve got oscillators that I like already, so why go there in a patch? Still, this would never stop me from putting anything through the proper paces, and in the case of Inertia, I’m glad I did. Even just using it as a VCO was more than worthwhile, serving up everything from sine waves to gritty sawtoothy waves. It tracked pretty well also, but it’s when you start patching in CV that it gets crazy…and sometimes cranky. Numerous times in my trials with Inertia, its inertia would come to a stop and I’d lose the sound/movement. Each time a quick toggling of the INTERFACE switch or twist of the MOMENT to jumpstart it and I was back in business. Again, I’d probably never use this as an oscillator, but it’s good to know that you can just in case you’re stuck on a desert island with a small modular setup and only enough room for…
More experimenting brought me to setting the RANGE on H, with RISE at 3:00, FALL at 7:00, MOMENT at 11:30, and SLEW at full CW to where I got a bounce after the initial trigger, kind of like ghost hits on a snare. It was a little like the bouncing ball effect except that each subsequent movement was consistent until the trigger came again, unlike the bouncing ball effect where each hit diminishes in size with succession. This could be really interesting for accenting melodic notes, or as mentioned, using it for ghost hits on a snare.
Again in H mode and in RISE/FALL mode, Inertia self oscillates with some very ring-moddy sounds, and CV’ing either the RISE or FALL with a saw wave executed a damn freaky space alarm. CV’ing all of the inputs simultaneously with various LFOs, VCOs, and external envelopes while self oscillating got sounds I’d never achieved before. Just some really interesting craziness. I suppose you can say that about a lot of things/modules, but still…there was something inherently different sounding about Inertia than other modules that I’ve patched the heck out of.
Running a triangle wave through its input while using a sawtooth LFO to CV the RISE at 11:00 and the other three controls at about 3:00 each, gave a distorted, stepped ramp at the output, with some interesting rhythmic abnormalities. Using Inertia as an LFO was rewarding, getting shapes that you won’t find on conventional modules or synths, but overall using it as an envelope generator was by far my favorite use for it. Patching into the CV inputs of Inertia and modulating the CV of a VCA, filter cutoff, resonance…dreamy stuff.
Inertia is an interesting take on one of the most storied–and emulated—modules of all time, and it definitely has its own worthwhile spin on it. My only gripe is that while I do like the size and spaciousness of the module, the DUSG and most of its emulators are all dual generators, and I’d love for that to be the case here. The interplay between having two sides of this could and would be pretty interesting and fruitful. With that in mind, I may have to procure a second Inertia; I can feel my momentum pulling me that way.
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