Cycle Instruments is the Brisbane/Reykjavik based brand behind the Tetrachords sequencer module. Started by two friends with a background in guitar playing, the idea behind the Tetrachords emerged out of their dissatisfaction with traditional analog step sequencers when it comes to building harmonies while playing and jamming with other musicians.

After many years of development in search for a more elegant way of sequencing and arranging melodic and harmonic ideas in the Eurorack format, the Tetrachords hit the stores in late 2023 and has since then steadily amassed a loyal fan base including high profile users like Sam Barker.

Intrigued by the module and wanting to know more about the backstory behind this unique sequencer, we reached out to Cycle Instruments for an interview after the recent Tetrachords workshop at SchneidersLaden. You can find a video recording of the workshop here.

In this conversation with Mathieu Pé of Stromkult, Cyle Instruments talk about the motivations and concepts behind the Tetrachords, the role of harmonic "maps" in electronic music-making and modular synthesis, building a harmony-based module that appeals to both music theory pros and beginners, as well plans for future firmware updates.

Stromkult (Mathieu Pé): Firstly, I would like to know where you come from musically — what was your musical background before you started making modules?

Cycle Instruments (Josh): I started learning guitar in high school and that's actually where I met Nick [the other half of Cycle Instruments]. He was my guitar teacher. And after I graduated from school, Nick invited me to come and work with him on a big outdoor theater show that happens once a year in Australia at New Year's, called the Fire Event at Woodford. And we worked together on that for four or five years, just making crazy soundtracks for these massive puppet shows and fire burns.

It was during that time that we started getting into modular together and started talking and dreaming of a different way of playing together — because we were jamming together on our modular systems and getting frustrated at not being able to jam in the way that we wanted to. So we decided to build our own sequencer, which took about eight years (laughs).

So you were obviously trying to solve a problem with that — how would you spell out that problem?

So this was around 2014/2015. We had these basic modular systems and we were trying to apply our shared musical knowledge into these modular jams. And the issue was that moving together harmonically with the sequencers that we had at the time felt very difficult and limiting.

Because as musicians, we all generate a mental “map” of places we will gravitate to harmonically, places that we like. It doesn't matter what instrument you play, you generate this in-built kind of map. And when you apply that to the modular as an instrument, you need an interface that helps you to quickly access that map — because otherwise, what happens is that you have much more knowledge than you can actually use in the system. Eurorack systems are so powerful that it can become really frustrating when you are limited by the interface and not able to get to a harmonic place [on your map] very quickly.

Most traditional sequencers — like the classic monophonic step sequencer — are incredibly limited when it comes to harmony, since they’re monophonic and un-quantised and step-based. So moving from one musical key to another requires a large amount of technical knowledge, like what relationships the notes have, and how much you actually need to move them to modulate to a new key or scale.

That was really just super clunky when we were jamming together with these traditional modular sequencers, because we’d hear something in the jam and be like "oh, let's go to the sixth note in this chord" , but it was impossible to just change everything super fast and move everything to the sixth and modulate the key. So we wanted to build something that would allow you to actually do that while playing a modular synth.

What made you gravitate to a Tetrachord approach for the sequencer? As far as I know, it's not a standard way of looking at keys and scales, it's mostly a concept found in Jazz and more improvisation based music.

That was really Nick’s spark, and it came from a video course by the late great jazz guitarist Pat Martino. In the course, Martino uses the Dorian mode, which is built from two identical minor tetrachords, and then shifts it to fit whatever the music is doing. That sparked the idea of having an interface with two tetrachords — both with simple identical controls that could combine into scales — along with the realisation that it could be a very approachable musical interface that could make scales more physical and less abstract.

A tetrachord basically is just a four note pattern, and you can combine two of them to make a scale. And because the patterns are short enough to understand and play with quickly, they make it easier to manipulate scales and compare them, improvise within them, and generally get a feel for them. By combining the six tetrachord types we’ve included in the module, you can create all of the commonly used scales and more. Essentially it's a way of building scales that is simpler to understand and easier to fit on a module, because you have these smaller building blocks. 

So if all you have to remember is the combination of two tetrachords to make a scale, you can yield the same musical results as with a traditional approach, but with much less "stuff" to manage and remember?

Yes, but I mean, you actually don’t really have to remember anything. You can just — honestly, most of the time when I'm using the tetrachords, I don't know what scale I'm in (laughs). It doesn't really matter, I’m just listening to the relationships between the notes and going to where I think will sound good. It's just a way of exploring scales and building scales that is a lot more accessible.

So the way things started was just you wanting to be able to jam on the modular while making use of your knowledge of music theory — but then you went beyond that because the module allows you to embrace the randomness of modular without having to sacrifice musicality?

Yeah! We wanted to build a device that could explore harmony in the modular world in the same really deep way in which a lot of modules let you explore sound. An interesting conundrum with music theory is that you can learn it in multiple ways, and probably the worst way of learning it is by learning the rules of music theory — certainly, it is one way of doing it, but it is a very limiting way of learning music. 

You know, it’s this weird feedback loop of “you need to experiment to learn what you like” and build that harmonic map I was talking about earlier. But to experiment, you need to know some ground rules, otherwise you’re just walking around with a blindfold on – so you need to learn the rules, but the rules limit the way in which you think about music and may stop you from going somewhere interesting. So what we're trying to do with the module is to just give you everything and make everything available to the user. The rules are built into the module if you want to think about them as rules, but if you are someone with no knowledge theory knowledge, you can also just start playing and exploring and figure out what you like and build your own "map" from that. So I really see working with the Tetrachords as a musical feedback loop of exploration and learning. 

That’s pretty much the best way to work: experimenting with your ears first and then later putting concepts on top — if need be — to give names to things you have already explored by ear.

Yeah. And this is so apparent when you compare, say, a folk musician with a classically trained musician. The folk musician often doesn't have the names or the rules for what they're doing, but they still have an extremely competent map of where they want to go harmonically and a refined sense of style. And then the classical musician might have a stronger sense of what we call “Western music theory”, but those two musicians are at an equal level of proficiency, they just think about things differently. And we want to create an interface that really enables both of those schools of thought and allows them to apply their approach to a modular system.

What are you proud of interface wise when it comes to the Tetrachords?

There's a number of things that I think make the module kind of special. One is the fact that it separates rhythm from harmony. So the module itself is not a sequencer in the sense that it doesn't have an internal clock — it doesn't care about time at all. You feed it time from something else, which opens it up to be just a harmonic processor, which is how it actually works in a lot of instruments — like, with a guitar, the right hand is doing the time and only the left hand is worried about the harmony. So we split that up and I think that's one really cool thing about the module.

The other thing is the modularity of the sequencing aspect. Like, if you want to, you can write a whole track in a single “pattern”, which is what we call a collection of notes. You can just build an entire track out of a single pattern, or you can then build multiple patterns into a “sequence”, like with a jazz standard where you have the A section and the B section, and a couple of chords in a sequence. You can then build these sequences into larger song arrangements, and then move between those in any way you want.

So in the context of a live performance, you can very easily perform the arrangement in a different way for each set. And I think that is super inspiring for musicians that are playing live with hardware, where you want to set something up and you want to have a predetermined aspect to the composition, but you also don't want it to be so locked in that you're just pressing play, you want to be able to express things in a different way each night. And I think the interface of the Tetrachords really allows for that.

I’ve coined a term for this ... it's a “sequantizer” (laughs).

Yes (laughs)!

Can you say something about the connectivity of the module — you have MIDI outs, you have USB-C and you also have the I²C protocol, so there’s a lot of options to implement it into different setups.

We really wanted the connectivity to just be like, whatever you throw at it. There's two reasons for that. One is that polyphonic synths are awesome and they provide so much harmony — and while building a polyphonic synth in modular is technically possible, it's just so much cooler to be able to just plug in any polysynth with MIDI and just have it do its thing, along with the benefits of the modular system. 

The other reason is that when you're jamming on a modular and you're recording the sound, it's so great to be able to split off and record the MIDI at the same time, and then be able to go back and break that MIDI out and re-record it in different ways or multitrack it, or just have that option of combining both of those worlds, not just the audio and the MIDI separately, but combining them.

So the USB-C on the module is a two-way connection? So you can have very complex, almost Black MIDI type stuff going on and change up things completely, right?

Yes! You could make an arrangement in Ableton and then send that MIDI to the Tetrachords, and then quantize that using the Tetrachords, and then send that to a hardware synth or the modular system over CV, and vice-versa. You could download a classical piece and then completely mash it up and re-quantise it to a new scale on the Tetrachords, and then send that to the modular and a bunch of polysynths.

And MIDI is very easy to find these days — could you plug in a Novation Launchpad like we have here, for example?

The module is not a MIDI host on its own, you need to have a powered MIDI controller. But anything that has its own power, you can then plug in and use.

Can you say something about the I²C protocol? To be honest, I myself only discovered the existence of I²C two days ago while preparing for this interview (laughs).

So I²C is a fairly niche protocol within the modular environment. Some manufacturers use it to talk between their modules and expanders, and some manufacturers open it up to other modules. What’s pretty cool about it is that you can connect two modules on the back of the modules, and then you don't need any cables on the front. Currently, we have worked with some specific modules — right now, the Expert Sleepers Disting EX and the Whimsical Raps Just Friends — to integrate them with the Tetrachords via I²C. In the case of the Just Friends, you can then have a six voice poly with just those two modules and no cables on the front. You can also daisy chain the I²C – currently there's only a single connection on the back of the Tetrachords, but the modules that you can connect to often have multiple, and you can daisy chain them together.

Given the very split opinions over whether music theory is good or bad for inspiration in the modular community — what's it been like designing a module that distills down concepts from music theory for a broader audience?

It's been interesting for us to talk about and market the module. Because while it could be seen as a very complex music theory device, the module actually is a very accessible way of getting into the theory side. So we’ve had a reception both from musicians with a strong music theory background that want to be able to apply that to the modular, as well as people with absolutely no theory background that have found a lot of potential in just sitting down and exploring the module.

So it's been super fun to see artists like Sam Barker perform with other traditionally trained, musicians like the saxophonist Bendik Giske, and to see how they are able to integrate the Tetrachords into their set in a way that enables them to play very harmonically rich and dynamic live shows. And conversely, we’ve also had people that have bought the module emailing us like, "I'm learning music theory through this module — I never thought about it like that before". That's been really exciting as well for us, and I think that also comes from Nick's many years as a music teacher, because during that process you get to understand how people learn music and what is important to teach.

“Which teaching device is working for which brain?”

It's obviously not for everyone, but I think there are ways of approaching the Tetrachords that enable you to learn without even really thinking about it.

Are you working on new firmware updates?

Yes, we are constantly working on the firmware. We haven't released an update for a while, but we are working very hard with constant feedback from our power users, and these firmware features are aimed at exploring deeper layers of what we already have, while obviously also tightening up things like the timing. So soon there'll be some more updates.

How final is the current MIDI implementation – do you have any plans when it comes to program changes?

The MIDI implementation is fairly comprehensive already, but we are working on adding things like program changes for the next update. We are adding more and more control on the MIDI side over the parameters. The future updates will be looking to completely enable almost all control in the MIDI protocol — currently it's about 80% of the entire module, so the hope is you will be able to run it bidirectionally with Elektron gear and other stuff and have them talk to each other.

Do you have any final thoughts or anything else you would like to say?

You know, the Eurorack world moves quite fast. There's a lot of modules coming on the market all the time. This module took a very long time to make, because we wanted to make something that had a long life and a kind of deep exploration potential — it’s been out for two years now, and I think it still has a lot of room for people to explore and to learn how to take full advantage of the depth it has. 

In general, I am really excited about the future of modular live performance. You know, some people say that mastering an instrument takes ten years of practice … and a lot of people got into modular synthesis about ten years ago! So I think over the next few years, we’ll see some modular live performers emerging that will really be taking the craft of performing live on a modular to the next level — whether that's combining modular with traditional instruments and musicians like Sam Barker or Lisa Morgenstern are doing, or just full on modular performances like JakoJako or Colin Benders. And I am also excited for manufacturers to respond to this and to make more sweet live performance orientated modules!

You can find out more about Cycle Instruments and the Tetrachords over at their website and watch a recording of their recent SchneidersLaden workshop with Sam Barker here.