Over the past decade, Instruo has carved out a distinct presence in the modular synth community, earning widespread appreciation for striking a rare balance between elegant design and deep musical utility. Founded in Glasgow by composer, educator, and instrument designer Jason Lim, the company has become known for its meticulously crafted Eurorack modules that are equally intuitive, visually stunning, and sonically deep. The brand's work often fuses analog tradition with thoughtful innovation, resulting in instruments that feel both timeless and forward-thinking. Modules like Arbhar, Cs-L, Lubadh, and Scion can easily fit any shortlist of Eurorack's instant classics, and rightfully so.
At the heart of Instruo’s design philosophy is a simple but potent idea: design selfishly. For Lim, that means building instruments that he genuinely wants to use himself—born entirely from personal creative needs, technical curiosity, or specific musical frustrations. That approach has led to a diverse and musically rich ecosystem of modules, whose usefulness and appeal, in reality, far exceeds Lim's original creatively selfish goal. And now, this landscape reaches a significant evolutionary step with the release of Seashell—a standalone semi-modular synthesizer that merges Instruo’s analog deftness with digital control, stereo processing, and deep software integration options.
In this interview, we trace Jason Lim’s journey from early experiments with electronics to the founding and evolution of Instruo. Along the way, we explore the guiding principles behind his designs, the collaborative engine driving the company forward, and how Seashell represents both a culmination and a new chapter in the Instruo story.
The Origins of Instruo
Perfect Circuit: What first drew you to electronic music and instrument design—and how did that path lead to the formation of Instruo?
Jason Lim: I've always had an interest in electronics. I think even before I properly took up an instrument. I definitely learned to solder when I was in primary school. I clearly remember getting hands-on at a workshop in a science museum when I was very young. It must have been a simple 555 timer circuit driving LEDs or something like that. My dad's soldering iron effectively became mine at a certain point.
I started on violin and piano when I was nine and later got into guitars and pedals in high school. I was always trying out wiring mods on my guitars and pedals. Many failed attempts, but it got to a point where I was earning beer money through college doing guitar tech work. Mostly balancing Floyd Rose bridges and setting action, but a lot of guitars got passed to me for pickup coil tap mods.
I didn’t properly get into synthesis and sound design until I was accepted into the Electronic Production and Design major at Berklee College of Music. I think I formally achieved enough credits to cover a minor in Acoustics and Electronics. I took so many electives, including: loudspeaker design, circuit bending/physical computing, and some introductory programming in Csound and then in C.
Troika triple oscillator
I think I learned C a little more thoroughly while trying to figure out some Arduino projects, integrating lighting design and controllers for a quadraphonic composition that eventually became my senior project. Designing Eurorack modules was a very logical progression after falling down the synthesis rabbit hole.
I actually co-founded my first modular company while still a student in the US. We can consider that a learning experience! Among many aspects of that time, I really learned a lot about how I would want to conduct my own business moving forward.
Instruo was a solo project for quite a while. I didn’t initially intend for it to become a modular brand. “Instruo” was the name I used for performing and collaborating as an artist. I designed the troika because I wanted more oscillators in my rack, and I documented the design and build process—which became the video that effectively launched Instruo.
As I got more settled in Glasgow and involved in the creative scene, I got to know a lot of very talented people who have since become long-time collaborators. I met Kian at a local synth DIY meetup and at various gigs. I met Sebastian through similar circles around the same time. We became good friends and started collaborating on new module designs. The working relationships that developed were very different from past experiences, and from the get-go I knew how I wanted to structure things to function fairly.
Instruo has always operated on a profit-sharing model. We've continued to adapt this approach as the team has grown. Glasgow is such a great city to be based in—there's so much activity in the creative scene.
Designing Selfishly
PC: Instruo modules are often noted for their architectural clarity, deep functionality, and sonic nuance. What underlying design principles or values have remained central to your approach?
JL: There’s one primary “rule” I’ve always tried to maintain as an overarching philosophy for Instruo designs: design selfishly.
It might sound oddly negative, but it’s something I embraced quite early on, and it’s been a significant guiding concept in Instruo’s journey.
What I really mean by “selfish” is that I always try to design for myself. The module or instrument has to be something I personally want to play with. Often, a module stems from either a technical curiosity –where I read about a circuit topology and fall down a research rabbit hole– or a musical idea where I don’t quite have the right controller or system setup to do something the way that feels most intuitive.
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An example of the former is the neóni oscillator module I designed in 2020/21. I revisited a Bernie Hutchins Electronotes article that beautifully articulated a circuit capable of through-zero FM. I added one of the blue-paneled Doepfer TZFM Doepfer TZFM oscillators to my rack at some point and became fascinated by the concept. I don’t think certain aspects of TZFM really clicked for me until I started tinkering with the circuits. Some of the oscillator sync tangents I explored with neóni were fun discoveries in themselves.
The harmonàig, on the other hand, is a much older design, and a perfect example of what I’d consider a “selfish” design. It started life as a Max/MSP patch back in college. I built it as an aid for designing practice routines for modal chord scales while preparing for guitar proficiency exams. I had taken an arranging class that focused heavily on voice leading using inversions. Things like using a iii-7b5 inversion in place of a tonic dominant 7. The bass can either define the root, or the context allows for the voicing to go a bit more “out.”
I still have a reharmonised arrangement of "Stella by Starlight" I wrote for an assignment. It's a standard I know well, but trying to re-harm using chord shapes that don't mean what my muscle memory thought outside of the new context. Brain scrambling!
Anyway, the harmonic engine that eventually became harmonàig was originally an interactive Max patch I used to learn my chord scales.
[Above: several iterations on the eventual Harmonaig design]
The module itself is a transposing instrument. Musical “do” is wherever your oscillator defines it. It quantizes with a diatonic modal harmonizer that covers all bases for 7th chords. Any non-diatonic chromatic root notes per mode still harmonize, but use my own curated choices of chord quality. Compositionally, these are somewhat rigid choices on my part. Most typical modal interchange options are included, but there are some chromatic tones where I deliberately opted for chords that voice lead in an interesting way.
In practice, I rarely use full 7th chords in a modular patch! Maybe if I’m doing something melodic with analog switches. But triads are plenty, and they stay much more “in.” There’s a diminished triad in one or two spots, but that’s fun!
For more specific use cases, I definitely recommend sequencing directly and bypassing the diatonic engine.
I think over the years I’ve grown to trust my gut to some extent. I do seek feedback from close friends and colleagues when I’m uncertain about an implementation detail, but when I have a clear intention or solution, I tend to ignore a lot of outside influence.
There’s a strong enough pattern of people using Instruo modules either the way I intended (or in completely new ways). This has been extremely gratifying and has helped build some confidence in trusting my judgement during design stages.
I think coming to technical design from a musical background, and designing as a means of solving problems for my own performances or composition, means the end results make at least some sense to others too. That’s one of the more rewarding aspects of all this.
Introducing Seashell
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PC: With its hybrid architecture and standalone format, Seashell feels like a significant shift in your design language. What sparked its development?
JL: Seashell began in a much more basic form. Although the earliest renders and sketches are really not far off the final product you see now.
I wanted to create something small and self-contained that was effectively a “complex oscillator in a box.” There are a handful of particular patches and configurations that I always return to on the Cš-L, and I had them in mind as the core sound sources for this (at the time unnamed) noise box.
A big inspiration in terms of early concept and—at least to some extent—form factor was the Noise Toaster by MFOS / Ray Wilson. It’s an incredible article, DIY resource, and tutorial all in one. I had a print copy from Make Magazine years ago that I read cover to cover multiple times. I never got around to building one of the kits specifically (I will someday), but I built sections of the circuit on breadboards and learned a ton about various core circuit fundamentals. The LFO and AD envelope in particular were key “lightbulb” moments for me in understanding some really important techniques.
The early Seashell sketch was inspired by this idea of a standalone little noise box – a mini palm-sized Cš-L I could sit with on the couch, headphones on, just making weird drones and textures.
I actually drew out some early circuit layouts and board designs for that nearly all-analogue version. I went with SOIC ICs and 0805/1206 passive components. There was an early plan to make it a semi-DIY project. The idea was to let people stencil, paste, place, and reflow SMT parts using hot air or a hot plate. Larger SMT parts could be hand-soldered.
Instruo shares its workspace with subSine Academy. I’ve collaborated with Simon Stokes, who runs the school, for many years. I wrote a synthesis and sound design course that I’ve taught both as weekend intensives and evening classes. I liked the idea of a weekend workshop where people could come and build their own standalone Instruo noise (toaster) box. It would be a more advanced build than typical kits, so we’d need a team helping guide the process—but the goal would be that everyone left with a working unit.
The size and form factor were really defined at this early stage. I was experimenting with a standard Hammond 1590B pedal enclosure, planning to remove the base plate and flip the enclosure upside-down to act as the chassis. The faceplate would mount to the screw points in the corners. I based the Seashell interface on that footprint.
I still have the original enclosure I bought as a test sample. I even spent some time trying to find brass screws I could use for mounting, because the enclosure used countersunk screws. I never quite found the right thread though.
The final voice structures: oscillators, wavefolder, filter, envelope, and cross modulation (similar to the Cš-L), were already locked in at that early stage.
PC: Seashell clearly draws from your earlier work with the Cš-L complex oscillator, but its interface is more streamlined. Plus, it is now a complete voice, with additional elements like a built-in filter, VCA, and envelope generator. How did you approach translating that depth into a more immediate, compact, self-contained format?
JL: The Cš-L was definitely a major influence on the Seashell. I’ve had a personal fascination with analog oscillator circuit topologies for many years. There’s something fundamental about them. They're the basis of subtractive synthesis, and I wanted to understand them at a low level.
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The idea of a “complex oscillator” adds a layer of chaotic fun. It’s a forced instability and interaction between analog cores. Early in my Eurorack journey, I had the chance to play with both the Make Noise DPO and the Verbos Complex Oscillator modules. I met Tony, Mark, and Gur (from TipTop) at various events over the years, and naturally was drawn to their brands even before I started developing my own modules.
The Cš-L combined ideas and configurations I wanted to explore, building upon the more “typical” complex oscillator concepts. Whether or not it was wise, I chose two different core circuits for the two oscillators: sawtooth-based for the top, triangle-based for the bottom. They behave quite differently but offer all the quirks in a single module. Doubling up on the wavefolders, each with its own FINAL output, further blurred the carrier/modulator roles. There were many voicing configurations I didn’t actually get to hear until I patched with the first (heavily circuit-bent) prototype. The way the core mixing at the wavefolders worked was a pleasant surprise! Parts of the signal flow were theoretical until that moment.
The Seashell takes a more optimized approach in its interface implementation, but my favorite go-to Cš-L voices very much guided its design. Originally, the synth was entirely analog. What is now the MACRO pot was initially a dual-gang pot for parallel FM index control. I’m very glad we expanded it into a digitally-controlled VCA setup for the FM buses! There were various decisions made "on a whim" during development that opened up doors that were not anticipated.
Even as digital elements were introduced, the analog signal flow stayed incredibly close to my original sketch and circuit layout.
PC: Did you encounter any specific challenges or breakthroughs in that process?
JL: One challenge I didn’t expect was the shift in canvas size. I’d been designing 3U Eurorack module interfaces for the better part of a decade, so laying out an interface that wasn’t 3U felt far more unfamiliar than I anticipated.
The size of the Seashell is essentially arbitrary!
I had that blank Hammond-style pedal enclosure that I really liked the feel of. My intent was from the beginning to make a little complex oscillator fit inside it. That pedal size defined the dimensions for the interface layout. The vertical spacing between the oscillators' COARSE and FINE pots I think matches that spacing between oscillators on the troika. So much of the process was trial and error though.
I don’t think the core layout ever changed much from that first version. When the project really got underway, we moved to a more bespoke enclosure design, which expanded the footprint slightly vertically, but the form factor stayed very close to the original. And I’m really happy with where it ended up.
Because I had a very dialled-in interface and instrument concept from the start, it worked extremely well as a focal point for the larger collaborative development that followed.
Behind The Sound
PC: The Diffuse Engine seems to play a central role in shaping Seashell’s sound, introducing subtle spatial effects and timbral smearing. What’s actually happening there, and what kind of behavior were you aiming for when developing it?
JL: I’ve worked with Kian for many years. We collaborated on some of the earliest Instruo modules: scíon, vinca, and eãs, among others. He’s the brain behind the Lubadh. That project began as an experiment in audio looping approaches, but quickly evolved into a deep research and development rabbit hole into broader digital signal processing (DSP). Around the same time, Sebastian and I were working on what would become the Arbhar (although if memory serves, the first Arbhar prototype was Seb's codebase running on a prototype Lubadh). Both modules went through parallel development for the most part, and they were Instruo’s first significant DSP-based designs.
While Kian and Sebastian focused on the software frameworks and audio engines for Lubadh and Arbhar, I handled the hardware design and firmware programming of the LED drivers. Those became signature elements in both modules—the visual feedback was crucial and I think has become quite a recognizable design element for Instruo.
Since then, the team has grown, and so has our expertise. Kian in particular has spent an insane amount of time learning DSP at a level that genuinely boggles my mind. There’s a fascinating history and lineage to reverb algorithms and diffusion networks, getting the lowdown from Kian on elements of this over a coffee or a beer is something I highly recommend.
The Diffuse Engine in the Seashell is a direct result of that R&D.
I gave Kian a vague pitch for the kind of thing I thought would benefit the Seashell’s mono-synth voice. In my own performance system, I’ve developed some go-to tricks for taking mono or paraphonic voices and making them feel much bigger and polished. Things like stereo enhancement from all-pass filtering into dampened short-delay feedback paths. These spatial techniques can turn a basic subtractive voice into something huge!
So the idea of a “single-knob stereo enhancer” became a priority. Our choice of DSP platform had to factor in the ability to run something like this.
I’m still blown away by what Kian managed to produce for the Diffuse engine. There was a lot of fine-tuning along the way. For a while we had a lot of varying degrees of reverberant test tones as a foundation noise floor in the workshop!
PC: The filter in Seashell has a smooth yet distinctive character. Can you tell us about the circuit topology and what informed its design? How did you decide the right filter to complement the oscillator’s already quite rich sonic possibilities?
JL: The Seashell’s filter has a bit of a backstory of its own.
My original prototype featured a very nice, slightly sluggish, resonant low-pass gate circuit. It was an experiment I’d wanted to try for a while: a classic Buchla-style vactrol-based LPG, but using a DIY approach. Because the circuit would be fully enclosed and in the dark, I used a combination of surface-mount LEDs with light-dependent resistors placed on top.
It worked well and sounded great, but there was a catch: vactrols are a big no-go these days... Technically, any optical component using LDRs is now discouraged due to various RoHS regulations. Specifically because of the cadmium content. The rules are a bit vague, but best practice is to avoid them altogether.
One logistical reason I initially went with the vactrol design was that it had very low current requirements—important because the Seashell needed to be as efficient as possible. But once I had to move away from that design, I needed a replacement that would still fit within those power constraints.
I started with a generic voltage-controlled Sallen-Key filter to test power draw. It worked, but it was quite “vanilla” sounding. I’d definitely grown attached to the character of the vactrol-based prototype.
I tapped out and made this problem a new problem for Noé (Éon Audio Design), who I’ve worked with for several years now. Noé is an incredibly knowledgeable engineer. I often bug Noé for second-opinion sanity checks on circuit designs. Some people might know his Procyon filter module, which he released with the Glasgow Synth Guild last year. His designs are always incredibly considered and very musical.
I set him the challenge of adapting my very boring new VCF prototype into something with a character closer to the vactrol version, and I think he absolutely nailed it. The feedback topology he came up with is something I’ve never seen before. It might actually be a completely new filter design!
The resonance control took a bit of persuasion to get just right, but I genuinely think we’ve ended up with something way more versatile and expressive than the original prototype even had.
PC: The software aspect seems to be as vital to the Seashell experience as its analog sound engine. How do you envision Seashell fitting into a musician’s workflow? Can you talk more specifically about the controller app? What especially exciting opportunities does it open?
JL: The Seashell started out as a much simpler device. Originally it was a drone box – something to noodle with on headphones while sitting on the couch. But what it became is a fully fledged semi-modular system.
As we moved into proper beta testing during development, we started to realize how broad the use cases were becoming.
In addition to Instruo being my main focus, I’ve also taught synthesis and sound design in both classroom and one-to-one settings. In recent years, I adapted my course to use Instruo modules within VCV Rack, which has been a lot of fun. There’s always a great moment when students move from following along patching in software to getting hands-on with a physical system.
So many people start their synthesis journey in software. Softsynths being so accessible. But that first experience of physically patching and interacting with hardware can be a real game-changer. The difference between using a virtual Cš-L with a mouse to immediately controlling frequency ratios with your hands and cables is massive. I’m really looking forward to incorporating the Seashell into my course.
What I hope Seashell can achieve is an ability to grow into whatever context it’s used in:
With just headphones, it’s a powerful standalone drone box. The analog signal path, combined with the Diffuse engine, gives it a polished, musical sound straight away.
Add a MIDI controller, and it becomes a plug-and-play monosynth capable of both East Coast and West Coast timbres, as well as some unique hybrids. The interaction between harmonic sub-ratios via oscillator sync, alongside analog FM and wavefolding, creates incredibly rich tones. Many of which I think can step into Chowning FM territory in tonal sonic terms.
A huge focus for us was the parallel development of the controller app and plug-in interface. The depth of digital control over the analog circuits has allowed us to implement parameter recall. Something we’ve never had in any of our modules before. The resulting workflow is completely new territory for Instruo. With USB audio and MIDI, the Seashell fits seamlessly into a laptop producer’s setup. Anyone familiar with softsynth workflows will feel right at home, but they’re now controlling real analog oscillators, filters, and wavefolders.
The software interface also opens up much more elaborate configurations. This is where its semi-modular nature really expands. The ARP 2600 has been an important synth to me, both in the contexts as a sound designer and as a synth designer. When I was first learning synthesis at college, we had a few very well-maintained original ARP 2600s. I also built myself a TTSH (a DIY clone) a few years back.
The 2600 is such a well-thought-out synth! It covers so many bases in its normalled configuration, but with patch points it becomes a proper sound design sandbox. That was a big inspiration to me when we were developing the Seashell's expanded capability.
PC: In a live or improvisational setting, how do you envision the balance between using Seashell’s front panel controls and relying on its software integration? Is the software meant more for pre-configuration, or do you see it as part of the performance toolkit?
JL: My personal workflow is a bit of a hybrid. If I’m working with a DAW or a sampler/sequencer setup, I like to patch voices on the fly and sample them into arrangements.
I can use the Seashell in much the same way I use my full performance rack. Honestly, it’s comparable in capability to many 6U systems I’ve used over the years. I’ll sample patches and build up audio to use as the foundation for a track or a score. The beauty of the Seashell is that I can do all of this with just my laptop and a single USB-C cable.
Another major advantage is not having to perfect a take in real time. I can fine-tune a MIDI sequence and micromanage all the parameter movements via automation—then print the audio straight into a track. As long as I keep note of any analogue configurations, I can save all the digital settings and fully recall the patch later.
In a live setting, the Seashell doesn’t take up much space on a tabletop, so I can easily include it as one of several voices in a performance rig. I prioritised hardware controls to make it a very hands-on and performable instrument.
Right now, I’m working on a live set that centres around the new 1010 Music Bento device. I’m sequencing the Seashell using its external instrument track and sampling audio into its looper. Between that, a live-controlled Seashell, a MIDI controller, and maybe a small 3U system—I think this might be my most portable live rig yet!
The Future of Instruo
PC: Despite its standalone capabilities, Seashell remains deeply modular in spirit. Do you see it as a new direction that you would like to explore further—integrated voices and hybrid workflows?
JL: The Seashell really does feel like the start of a new chapter. Its launch was definitely more stressful than previous module releases. Releasing modules is much more in my comfort zone! The Instruo module range is pretty extensive at this point, and I’ve got that process down: timelines, batch sizes, asset prep—it’s all very familiar.
The Eurorack community is really amazing and could not have been more supportive through the nearly ten years of growing Instruo. I’ve learned a huge amount personally, and our full-time development team has evolved massively.
Designing modules has always felt like part of a larger goal: to create complete instruments. The modular format is a design sandbox. You can isolate and deeply refine an oscillator, a filter, an envelope, or a VCA –components parts of a more typical synth– until it becomes its own standalone product. But taking a step back, the real instrument is the modular system itself. A well-populated 6U rack can be a complete, bespoke instrument optimised for a particular musical context.
The R&D that went into the Seashell extends well beyond the product itself. It was the anchor point for a massive development push. I defined the majority of its top-level and analog features. The hybrid functionality design that followed became a full-team focus. At peak, there were eight of us working full-time on it!
Planning and releasing a self-contained, standalone instrument was daunting. The Seashell’s skeletal concept that I’d sketched out years earlier gave the project some grounding. But as we introduced the digital integration and a software interface, the potential feature set grew exponentially. We had to be careful and limit the "feature creep".
In the process, we definitely all levelled up as a design team. We now have our own bespoke DSP libraries, embedded frameworks, communications protocols for hardware/software integration, and app/plug-in development capability. When we first sat down to map out the development roadmap, there were so many unknowns. Now we’ve got that foundation in place for all future projects.
There’s also still so much room for Seashell to grow. We’re going to continue working closely with this new Seashell community to explore all sorts of ideas (the workshop whiteboard is already full again!).
And work has already started on the next thing! I’ve also returned to some analog module designs that were on pause during Seashell development.
The module side of Instruo definitely won’t be slowing down.
PC: Finally, looking ahead: are there synthesis techniques or interface concepts you’re currently exploring—or areas of instrument design you haven’t tackled yet but feel drawn toward?
JL: More oscillators, for sure!
Only partially joking! I’ve already got some paused prototypes that I’m keen to revisit.
Thanks to the capabilities we’ve developed through the Seashell project, I think there are a lot of new hybrid approaches that could lead to completely fresh results.
The team of collaborators I’ve been lucky enough to work with over the years has become a real creative force. There are more ideas bouncing around than we know what to do with! We learned so much through the Seashell development cycle, not just technically, but also in how we function as a team.
Our in-house team meetings are referred to as “band meetings.” Most of us have musical backgrounds and experience in bands, past or present. Co-designing instruments actually feels a lot like songwriting in a band: there’s problem-solving, negotiation, improvisation. Sometimes the solution appears out of nowhere, or a casual idea becomes a whole new module in a few days. Other times, it's a slow grind... weeks of banging your head against a keyboard or soldering iron until something clicks.
Our back catalog spans a huge range of module types. I’ve never stopped experimenting in the analogue domain, and our DSP capabilities have only grown since Arbhar and Lubadh.
So if the question is, “What’s Instruo going to design next?”
The answer is: "Everything!"
