Ordovician Restraint

State Variable Filter

In what could possibly be seen as an intentional effort to confuse the masses and keep everyone on their respective toes, the good folks at VF make for you this offering of an analog state variable filter. Wait. Hold on. An SVF. In 2024. Don’t you mean resonant wave folder? Or perhaps Adaptive Neural Buffer? Or some sort of embedded app that runs an authentic copy of Rebirth, but with incorporated CV control of the vintage 303 emulator’s resonance? No? Just an SVF? Is it at least based off a component-accurate replica of some rare vintage French or Japanese thing? Or is it a clone of this one popular thing, but
cheaper and with that one additional feature I wrote you about? What about another Ripples, but like, quad? No? Then what the hell damn guy – what’s the deal!?

No deal. It’s just a filter that came by way of a couple projects of necessity converging into one solid stream that made sense to put out into the wild as a build your own adventure as well as a complete package for assorted VF completionists and well-wishers. That said, here’s how it came about:

Project of Necessity 1: For those down with my entire thing, you might recall that one of my DIY things out there is a Eurorack conversion of the Ciat-Lonbarde Duber filter. You may also recall that I later
offered a revision to said filter to make things slightly more accurate, as well as slightly more appealing to those outside the periphery of the cult of Blasser. While I was doing that, I also took a quick trip into the deep reeds to figure out what made this filter unique and what can further be done to convert this critter from a stand-along bandpass intended to be played with worms and steel wool to something that could be equally at home with the boom-bap. Through these efforts, the entire power section was reworked from a 9v unipolar to a +/- 12v bipolar – meaning less crunch and more headroom – whoopee! Next up was the realization that once you strip the unipolar quirkiness our of the way, the filter topology is relatively straightforward – so adding high and lowpass outputs was a given. Likewise, the switch was a serendipitous suggestion from a friend – at least in my wacky world of filters, I only ever end up using one of the several outputs on the beast so why not offer the same – less jacks, smaller footprint, etc. Always a good thing when one of your rules of construction is to keep things through hole for the sake of the DIY scene. So up for high, down for low and bandpass in the middle. Finally, while the Duber is a dual resonant bandpass filter, there’s nothing stopping us from splitting the circuit into a single filter. I mean, it’s modular, so if you really want to replicate, just smack two of these together and mix the signals on the output. So yeah, that’s part one.

Project of Necessity 2 came by way of the day job where I was tasked to develop a modular synth building workshop that would yield a fully functional one voice instrument. Yeah, I know, working for the man. Keeping in mind that time would be limited and there would be a learning curve, I’d need a filter that could demonstrate multiple types of filtration, but also have a modest parts count, ideally with components that can take a slight level of abuse without going kablooey. Seeing as the previous trip into the weeds produced something relatively close to these specs, the question was how to adapt this beast to fit the proverbial picture – and the easiest way to do accomplish this would be to rework the CV section. In the CL Duber, CV processing comes by way of nests of transistors pulled from Serge designs. Fun and freaky, for sure, but transistors can be temperamental. However, seeing as the previous modifications left me with an available OTA channel, why not replace the dual Serge-inspired CV control with a single traditional VCA and call it a day? Which I pretty much did and hey, mischief managed – and in a compact 8 hp package to boot.

And that’s pretty much the gist of it. It’s small, sounds good, and is a relatively decent build. Does it cover territory that countless other builders have already covered? Sure, but that doesn’t mean it’s not special. Hell, when you put it that way, it almost sounds sort of honest and wholesome. So I guess there’s also that. Care to check it out?

And now onto questions.

First up, the name. Obviously not a pun in Spanish like all the rest. So it goes. I thought I had a theme going, but this one just kind of landed. Here’s what’s up. As I live in a super-nerdy science town, one of the rainy-day activities we’re prone to patronizing is the Museum of the Earth – which is a pretty cool pile of fossils considering the local geologic record had us as a prehistoric shallow sea – meaning oodles of trilobites all around the omni-abundant slabs of shale. Dinosaurs… not so much. Though there is a Mastodon skeleton, so it’s not all ancient proto-lobsters. As it happens, I was at said locale one day (which is obviously rife with the term “Ordovician”) and happened to remember my first encounter with said word which was the first time I mounted a show in a gallery. I was an intern at a NYC art spot called the Tank and the piece was called “Reimagining the Ordovician Gothic: Fossils From the Golden Age of Spam” – kind of an abstract title for sure, but the gist of it was that it was a collection of thousands of pieces of “spam poetry” – which, for those that don’t remember, were strings of strange phrases and words tacked onto various unsolicited emails in the pre-Google era, designed to circumvent primordial spam filters. The ting is, some of the stuff was outright amazing – like generative cut-up poetry from the depths of the Twilight Zone. Of course times and technology changed and now we’re stuck in a post-industrial hellscape where all things digital are market-driven generative garbage, but hey, in those kinder, innocent times, maybe just maybe man and machine shared a common interest in the poetic arts – which at least in one case manifested as a band dedicated entirely to “spam poetry” (or spoetry) – later on they became a Cardiacs cover band, which is equally ok in my book. So yeah, there’s the name. Restraint obviously referring to the filtration and eventual elimination of unwanted information. So also poetic? Either way, cool name, right?

On the artwork, for those willing to squint and believe me, it’s a wizard fighting a dinosaur. Because of course it is. Just for that reason alone you should probably get this thing.

https://vauxflores.com/electronics/ordovician-restraint/