Rungling in the Continuous and Discrete

Added: 2026-05-31

[00:00:00]Hello, this is episode 14 of new uses for old circuits wrungling in the continuous and discreet. Rob Hordike is probably someone who needs no introduction to viewers of this channel.

[00:00:12]But for those unfamiliar, he was a synthesizer designer primarily interested in creating instruments that were, in his words, bent by design. Rob wasn't so interested in creating instruments that were predictable. the kinds of studio workh horses that producers reach for when they need to lay down a baseline. Rob's interests lay more in embracing chaos and in creating instruments that would be a source of inspiration. Thomas Dolby once said, I think that the platonic ideal of a synthesizer is a machine that would take a sound that's in your head and manifest it in the quickest way possible. Rob's instruments were basically the polar opposite of that idea. turn them on and you'd be greeted with a bunch of sounds and you have no idea where the instrument is going to go next. Perhaps his most famous instrument is the Blippu box. An instrument which took two oscillators, two filters, and tied them all together with the mysterious circuit called the Rungler. The Wrungler also appears in his Benjelin design, which is a kind of open-source design, and you can find many versions of Benjelins in Eurorack. And Rob also handbuilt beautiful and huge 5U modular systems.

[00:01:26]But pretty much all of Rob's instruments centered around the concept of the Wrungler, the circuit that probably best encapsulates all of his ideas as a designer and artist. In the previous video, we looked at the tension between continuous and discrete signals. And no circuit exploits this tension better than the rungler. So, in this video, we're going to dive into the rungler, see how it works, see how it exploits this tension between the continuous and discrete, and build a rungler from scratch to better understand everything about it. I've been reticent to introduce new gear into this channel because I want this channel to focus on ideas and techniques. Ideas you can take into your own practice and implement whether you're using a surge synthesizer, a URAC modular synthesizer, a software modular synthesizer environment like VCVR rack or within Bitwig, or even ideas you can take to a synthesizer as ubiquitous as say a microcorg. But because this video is more or less dedicated to the work of Rob Hordike, someone I admire very deeply and who sadly died a few years ago, we're going to start by listening to the sounds of the Blipoo Box to hear rumbling in action. And while I get a lot of enjoyment by taking the rungler outputs of my Blipoo box and patching them within my Surge system, the primary motivation of this video is to build a Wrungler ourselves using the elements in the Surge. I grew up outside of New York in the '9s and my parents got cable I think around 1999 or something. And as a budding little gourmand, I enjoyed watching the Food Network. I learned a lot as a kid about how to cook, and I think it probably has a little bit to do with why I enjoy cooking so much to this day. One key thing I learned from some of my favorite shows on the Food Network was about the idea of the unasker, the object in a kitchen that only does one thing and is good for basically nothing else. Think of a garlic press or a speciallydesed object for squeezing a lemon. Growing up in the consumerrist 90s, it seemed like every kitchen needed to have about 5,000 different objects and implements just to cook the most basic meals. And what I came to learn is that you don't need any of these unitaskers. If you have just a handful of the most basic tools, then with enough experience and knowledge, really knowing how to cook, you can use a handful of basic tools to create the most elaborate meals. You maybe need three knives. A chef's knife, a pairing knife, and a bread knife. A handful of pans, maybe one to make stock in, and then one or two. Maybe a cast iron and carbon steel to to cook steaks and sauté all sorts of things. And maybe a mortar and pestle or some kind of blender thing, but outside of that, you really didn't need anything else to cook pretty much everything. This is in part, I think, why I became so enamored with the Surge. The Surge embodies this kind of principle. It gives you a handful of the most low-level tools and allows you to build complicated things from those tools. It seemed like a bit of a corrective to the feeling that would be generated mostly by companies trying to sell you something that you need some new piece of gear, that you need some new tool, when in fact with just a bit of thinking, you could probably build what you thought you needed within the surge. Now, with a bit of experience, you'll probably find over time that there are a handful of things that are a bit specialized, but that you do turn to pretty much all the time. And it's helpful to have specific tools for those. That's why I have a Blip Boooo box. It's a specialized object that I use basically all the time. But it's also a bit more than that. It's a instrument in its own right. You build a relationship with it, learn how to play it, even though it in many ways plays you. But anyway, let's first listen to a bit of the sounds of the Blipoo Box and then we'll dive into recreating the Blipoo Box in a reduced sense on the Surge in order to better understand what exactly the Rungler is, what it's doing, how it's playing with these ideas of continuous and discreet to give rise to chaotic behavior. Before we jump in, I should probably uh plug the Patreon. So, if you like this video, if you like what I do, please do check out the Patreon in the link below to help support this work. This is the Blippu Box. Probably Rob Hordike's most legendary instrument and one that took a lot of the special sauce in his large five systems and boiled them down to a single standalone instrument. Like I said, I don't want this to become a gear review channel, but the Blippoo Box is genuinely one of the most interesting instruments that I've encountered in my entire time of making music. And since so much of this channel is indebted to Hord Dyke's work, I thought it would be a good moment to look at the Blipoo Box and in particular look at how the Wrungler works to give you a better idea of some of the principles that we're going to try to recreate later on the surge. So, the Blippo box has two oscillators, A and B.

[00:06:43]And the core of the Blippo box is the famous Wrungler. The Wrungler is an eight stage shift register, and it takes in two inputs, a data input and a clock input. With every clock pulse that comes in, the Wrungler looks at the signal in the data input and samples it and holds it in stage one. And at every clock pulse, the sampled value that's held in stage one is moved down the line to stage two. And then stage three, four, five, six, all the way down the line until stage 8, whatever is in stage 8 is just no longer held and effectively deleted. So every clock pulse samples a new piece of data from whatever is in the data input and shifts the rest of the data down this line. Now, there are two funny quirks to the runler. One is you'll realize that I don't have continuous voltage values in here. Usual voltage values in the surge or any synthesizer would be from 0 to 5 volts for example, but I only have ones and zeros. That's because the Wrungler effectively takes whatever it sees in the data input and quantizes it to a resolution of one bit. So effectively if we have as our data input a ramp wave moving smoothly from 0 to 5 volts then whenever a clock pulse appears the wrangler's going to try to sample that input signal and basically threshold it to be either zero or one. That probably means that if the ramp wave is say from 0 to 2 1/2 volts it's set to zero and from 2 1/2 volts to 5 is set to one. But I I can't really be sure exactly how that thresholding works. But so while the Wrungler samples continuous voltage, it only stores digital binary information. And then the other fun thing about the Rungler is that the output isn't the eighth stage. That would essentially give you just a kind of shift register delay thing. So a circuit that only samples an input voltage and spits it back out at you a certain number of clock pulses later.

[00:08:38]The runler output is the output of a digital to analog converter within the runler circuit. This digital to analog converter is looking at the binary word within the rungler at any given time and converting it to an analog signal. So if the runler were all ones, then we'd have the highest possible voltage at the DAC output, probably 5 volts. And if the rungler were full of zeros, we'd get the lowest, probably 0 volts. And for any combination in between, the DAC converts this binary word at every moment in the runler into an analog voltage with the information in stage one being the most significant bit and the information in stage 8 being the least significant bit.

[00:09:20]So the Blippoo box has two oscillators and it uses oscillator A as the data input to the runler and oscillator B as the clocking input to the runler. And then the Wrungler is available as a modulation source in this middle row of knobs as well as the uh banana output jacks here. The Bloop Boooo Box actually has two separate runglers, but let's forget about that for now. So, we turn up the volume on the Bloopoo box. We'll hear we hear oscillator A primarily. And that's it sounds a bit kooky. I mean, we can change the frequency of oscillator A.

[00:09:57]It sounds a bit odd because it's sent into this twin peak resonant filter which uh is doing a lot of things. And also it's not just oscillator A going into the twin peak filter, but it's a combination of oscillators A and B. They're basically run through a comparator. But for the most part, oscillator A is our data input to the runler and oscillator B is our clock. So, we can start to hear the Rungler in action. It's actually easier to hear its effect on the filters.

[00:10:38]Let's turn up the clock rate of the run.

[00:10:49]And of course, by sending the rumbler into either of the oscillators, we get a feedback loop, which starts to give the box its signature If you're a follower of this channel and this is your first time encountering the Bluy Box, then it should be pretty apparent why I love this thing so much.

[00:12:05]Don't contact The Blippo Box is truly the source of some of the most gastric sounds out there.

[00:12:58]The Blippoo Box is hours and hours of fun. And there's a lot more going on in the Blipoo Box. The filter design is very strange. And there's this sample and hold circuit uh that Rob calls a time warp circuit. Uh we'll get into that maybe in some other video down the line. But for now, let's take this idea of two oscillators and a runler and try to make our own uh runler and sort of blipoo box inspired patch on the surge.

[00:13:32]The core of the Wrungler is of course the eight stage shift register which is basically eight sample and holds linked together which on the surge would mean linking eight stepped function generators together. Now I'm lucky enough to have four SSGs in my system. I have two here and then two as part of the dual GTO here. And while I think a system containing eight SSGs sounds like a whole lot of fun, uh it would be admittedly a little impractical. And also for the purposes of this video, patching eight SSGs together is a lot of cables and just gets unwieldy and is a little unclear. So here we're just going to patch three SSGs. We're going to use a threebit shift register. So to start building the core of our rumbler, we'll take the output of our first stage, our first step generator. It's a sample and hold circuit and patch it to the input of a second stage. And then we'll take the output of that second stage and patch it over to the input of our third stage here in the dual GTO. The blueoo box uses two oscillators, one for the data input and the other for the clocking input of the rumbler. So we'll use these two oscillators here. And we'll use this as our primary oscillator as our data input. So that is just going to go straight in to the first SSG. And we'll use this second oscillator to do our clocking. Now, clocking becomes a bit of a tricky subject here. In principle, it seems reasonable that we could take the output here and send it into all three sample inputs on our chain of SSGS. And then with every clock pulse coming out of this oscillator, we would sample whatever is in the data input at the first and whatever is being held in the first SSG would move down to the next stage and move down subsequently to the third stage. But in reality, that doesn't work. Everything just happens way too fast. And if our clock triggers all three sample and hold stages at once, they will all update to whatever is being sampled at the input of the first. So we won't get this smooth flow of data. Rather, all stages will match whatever is in stage one. So basically what we want is to first trigger the last stage to update to whatever is being held in stage two.

[00:15:50]Then a very short time later, trigger stage two to take whatever is currently in stage one. And then another short time later, trigger stage one to sample the new value from our primary oscillator. And we can do this a handful of ways using trigger delays, slope generators, things like that. But the easiest way is to actually just use the TKB as a trigger sequencer. We will take the clock output of our clocking oscillator and clock our TKB. And then I'm going to take the stage 4 pulse out of the TKB and go into reset to give us a three stage sequence. I don't really know if you can see on the video, but if I slow down the clocking oscillator, you can see the LED moving through the first three stages of the TKB. And now what we can do is take the stage one output to sample our last stage, stage two to sample our second stage, and stage three to sample our first stage.

[00:16:58]Basically kind of working in reverse. So now you can see this already work. If I slow down the clock a little more, you can see now the data moving down. It's nice and clear with the LEDs on the first two SSGs. You can see this data sampled from the primary oscillator and then shift on down the line. And just for a quick demonstration, we'll take a triangle wave from a different oscillator and listen to it and use the output of our last stage in the shift register to sequence it.

[00:17:35]And we just hear a basic sequence with the clock rate determining the the rate of that sequence. The primary oscillator is being sampled at the clock rate. If we slow the primary oscillator way down, we'll hear it's sampling this kind of ramp structure.

[00:17:55]But that's of course not at all what the Wrungler does. The Wrungler doesn't just take the final output for of the shift register. It uses a digital to analog converter to take the information in the shift register and combine it into a digital word. That of course reminds me that we actually need to fix the input of the Wungler here because the first sample and hold is sampling a continuous value and it's obviously being allowed to be any voltage value whereas we need this input to be thresholded and set to either a high or low state. So what we'll do is we'll use a comparator.

[00:18:28]We'll take our primary oscillator and go into the input of a comparator and then take the comparator output and patch that to the data input. And now you see that we're only getting a high or low state.

[00:18:44]So whereas previously in our shift register each stage could hold a voltage of any value, now it can only hold a voltage value of either high or low. And the Wungler output, the digital to analog converter, looks at the binary word in the shift register at any given moment and outputs that as an analog voltage. Now, one thing uh the search system clearly doesn't have is a digital to analog converter, but we can fake one using a dual processor. What we're going to do is mix the three shift register outputs using a dual processor and give them each an individual weight. The bit in stage one we'll send into channel one and we'll set the attenuator to max giving it the maximum amount of weight.

[00:19:26]The bit in stage two we will send into channel two of the dual processor and set the attenuator around halfway or maybe 2/ird of the way to give it a medium weight. And the bit in stage three over here in the GTO we will send into channel 3 of the dual processor and set the attenuverter to around 1/3 or 20% or or whatever. This is all pretty imprecise but effectively treating the third bit as the least significant bit.

[00:19:54]So now this dual processor is our runler output. We can look at it on the scope and let's use it to control the frequency of that triangle wave oscillator.

[00:20:14]And now it's the interaction between the frequencies of the clocking oscillator and the primary oscillator that give us these interesting and strange patterns.

[00:20:33]And while this is a very fun and interesting pattern generator, it's missing one crucial aspect, which is, of course, feedback. Our primary and clocking oscillator are driving this whole system, but they're not influenced by anything other than my hands turning their frequency controls. The really key controls on the Blipoo box are the ones that allow you to send the runler outputs back to the source oscillator frequencies. So, we'll take our Wrungler output and go to the frequency control of our primary oscillator and the frequency control of our clocking oscillator. We'll take the Wrungler output and drive this independent triangle wave oscillator to hear what that sounds like.

[00:21:29]So here we see the Wrungler's power as a pattern generator and it creates chaotic behavior by doing what we did in the previous video by playing with this tension between the continuous and the discrete. we have a continuous oscillator being sampled and digitized into the Wrungler where that oscillator now only exists as a digital stream of bits. That digital stream of bits of zeros and ones is then converted into an analog voltage using a digital to analog converter and then sent back to control our oscillator completing this circular transformation from continuous to discrete and back to continuous again.

[00:22:07]Let's make something a little more interesting. Let's actually use the pulse output of our oscillator here.

[00:22:15]Send it to our variable Q filter and then send the variable Q lowass filter out to our stereo mixer.

[00:22:26]And of course, we got to wrangle the filter.

[00:22:39]Ah, one of the interesting things about the Blipoo box is that it doesn't have a third oscillator, which is the one we listen but rather we listen to the combination of both of our oscillators.

[00:23:13]So instead of listening to this other unrelated oscillator that's not totally embedded into the system, let's listen to the system itself by taking the primary oscillator and the clocking oscillator and running them both into a comparator.

[00:23:36]And then we'll send the comparator output to the audio input of our filter.

[00:23:41]And apologies, uh, this is generally the point in the video where my attempts at color coding patch cables uh, starts to fall apart.

[00:23:55]First, we'll just listen to it.

[00:24:05]The raw comparator output is not always the best uh sound source. But if we take the rungler and start to wrungle the filter again crossing across clean The Twin Peak resonator on the Blippo box uses very resonant filters and it uses two of them in a somewhat strange configuration. Let's try to mimic that configuration with our setup here. What we want is to take our comparator output and send it into a first highly resonant filter. And what we'll do is we'll take the band pass output of that and put it into our just a basic audio mixer down here. And then we will take the lowass filter output of that first variable Q and run it into the input of a second variable Q and set that to very very high resonance. And we'll take that band pass filter output and run into the first channel of this audio mixer, but we'll set the phase to negative so that the second filter is being subtracted from the first filter. Obviously, if this first filter has a really low frequency and the second filter is set to a higher frequency, then nothing's going to happen because that second filter is using the low pass filter output of the first as its audio source.

[00:25:45]But by doing this weird phase inversion trick, we can get around some of those issues. The Bloopoo box doesn't have a resonant EQ, but I do. So, we're going to use it and do my typical comb filtering stereo move.

[00:26:15]And of course, we also need to rumble this second filter.

[00:26:50]One thing we can't do on the Blipper box, but which we can do here is we have access to the slooh rate on all of our sample and hold stages in the runler chain in the surge SSG. This rate control basically slooh whatever is coming into the input before it actually hits the holding stage. So it basically kind of slooh limits the deviation from one stage to the next.

[00:27:28]It can be a bit of a It can be quite a sensitive control, but potentially a very interesting one.

[00:27:45]One funny thing that Benjelin has is a sort of circular FM uh between the two driving oscillators. So uh let's see what that sounds like by taking these sine wave outputs and doing a little circular FM.

[00:28:09]Kind of want to hear what this sounds like with a little spring reverb on it.

[00:29:25]And you know, I can't help myself. Let's uh throw a phaser in here.

[00:29:38]And we will of course run phaser.

[00:30:25]Heat. Heat.

[00:30:59]Rob Hordike's Wrungler is all about playing in this tension between continuous and discrete signals. That constant circular transformation from continuous to discrete and back to continuous again leads to all sorts of strange patterns and we start to see chaotic behavior emerge. And it's what makes instruments like the Blipoo box so compelling.

[00:31:25]But with a bit of understanding of how these circuits work, we can build them ourselves and start to explore and immerse ourselves into the world of chaos.