Welcome to a new 20 Questions series interview this time with Ale of Bartola Instruments. You may be aware of their upcoming valve filter ‘Swell’ that I shared a first patch video with recently. You can check that out here and lets get right into it!
Alejandro (Ale) is the founder of Bartola Instruments. He spent over thirty years designing unique valve (tube) circuits for hi-fi, learning exactly how they should behave. He now applies that knowledge in the opposite direction: building Eurorack modules around the moments when vintage components step outside what they were designed to do. Bartola is launching its first released module, Swell very soon and there’s also with a deep product line already in development, from utility modules to complex oscillators. He’s based in London, originally from Buenos Aires, and this is his first interview in the modular world.
01 How would you introduce yourself to someone who has no idea who you are and no idea of the modular, synth, & music tech spaces?
Have you ever heard music that sounds alive and you can’t pinpoint why? Like it’s breathing or shifting? That’s often what modular synthesis sounds like to someone encountering it for the first time.
Modular synth is this strange, endlessly flexible thing – building your own instrument from scratch, every time you play. Those intimidating cables you see draped across a musician’s setup? It’s less like playing a traditional instrument and more like designing one, in the moment, while the music is happening.
I’m Alejandro – Ale – and I make some of those components. Specifically, I build them around vintage technology including valves (tubes in the US) – the same glowing glass tubes that powered TVs, radios and amplifiers sixty years ago. I’m drawn to them because they do something modern electronics struggles to replicate: they add warmth, an organic imperfection that makes sound feel alive rather than calculated. No two valves behave exactly the same, which means no two sounds are ever exactly the same either.
Bartola Instruments (my company) takes its name from Argentine slang for going completely with the flow, carefree. That’s the spirit behind everything I make: instruments built for exploration, for following a sound wherever it leads, without a map.
02 How would you introduce yourself to someone who is aware of modular, synth & music tech worlds?
I’m Alejandro – Ale, founder of Bartola Instruments. I spent 30 years making valve circuits as linear and transparent as possible for hi-fi. Then Eurorack happened and I flipped everything – I now use those same skills to find exactly where tubes and other components or circuits misbehave, and build modules around that. Valve circuitry blended with digital platforms, each doing what the other can’t. If you’re looking for new sounds that sit outside what is out there, that’s what Bartola is for.
I’ve built over 110 prototypes since 2019. I’m now taking those designs to market – starting with Swell, a 14HP valve harmonic filter built around a Soviet Cold War-era military valve, launching end of June.
Each module has its own character – no two valves ever behave exactly alike, which means no two Bartola modules sound identical either. That unpredictability is the point – it’s baked into what Bartola is.
03 What were your early influences for getting into what you do now?
It started at age 10, dismantling every piece of electronics I could get my hands on and rarely putting it back together. Black and white TV sets were my favourite, especially if they had valves inside. That was my first encounter with tubes, and I was immediately fascinated and luckily never electrocuted.
As a teenager I played saxophone, always chasing ways to process and electrify the sound. I built my own stomp-boxes and effects naturally becoming the geek in charge of recording and live sound for every band I was in. I also built a Chapman Stick from scratch with my dad back in Argentina, with no plans and no prior knowledge (see pictures below). We figured it out as we went. That spirit of building without a detailed map has stayed with me.
Musically, I was drawn early to jazz and the avant-garde, artists like Coltrane, Pharoah Sanders, Piazzolla, Ornette Coleman, Keith Tippett as well as Steve Reich and John Cage. I have a complex foundational cocktail of musical influence which also included Frank Zappa, Jimi Hendrix, the Canterbury Scene, Van der Graaf Generator, Nick Cave, John Cale, Lou Reed, Zeppelin, Patti Smith, the early punk scene as well as electronic music.
The expressiveness of wind instruments, the way a saxophonist can bend a note or breathe life into a phrase, that’s something I’ve always tried to chase in electronic design. In the ’90s I was playing electrified saxophone in the Buenos Aires underground rave scene, bridging those two worlds.
Moving to London 20 years ago deepened everything. I went further into designing hi-fi, valve amplifiers, speakers, turntables going fully down the rabbit hole. I’m a hoarder by nature: I’ve collected thousands of valves and vintage parts over the years. More than I could use in several lifetimes. My wife knows this, and still loves me.
04 What was the first thing you created either as Bartola Instruments or something for yourself?
As Bartola Instruments, the first design I made was a valve-based Fuzz distortion module. It consisted of two cascaded valves providing a lot of gain and saturation, packed into 8HP. It had no CV controls, the timbre was shaped with a bias pot and a volume/gain control.
It was a simple and fast design, but it taught me a lot about designing for Eurorack: panel aesthetics, layout, UX and it opened the door to discovering I could genuinely shape different sound timbres with my own circuits.
I shared this module with several musicians around the world as a gift in exchange for their opinion and improvement ideas.
From that initial distortion circuit, I shifted towards building a full system. I designed VCOs, envelope followers, generators, LPGs, filters, VCAs, mixers, gate sequencers, random and chaos generators which helped me learn a lot about synths. I also purchased hundreds of modules to learn from them and improve my own designs. One of the VCOs, the VCO2, I only made three units, it’s a large module I can’t fit in my own rack, but Hélène Vogelsinger uses it actively in her setup (see the pictures below).
05 What was the first product you brought to market and how was that received?
I made several iterations of classic ladder filters and multi-mode ones. One LPF I designed two years ago I named “Swell”. The name came from a late-night session experimenting with morphing drones. About ten units were shared with musicians and Eurorack designers for feedback.
The reaction was unanimous: take it to market. Despite some asking for it to be a small module, I held to the 14HP format. Ergonomics and panel space mattered more than saving a couple of HP. That conviction, and the confidence the feedback gave me, led to the decision to launch Bartola with Swell as the first module of a larger series.
06 How did making that first product influence the next one? Any lessons learned to pass onto others?
I normally work on four or five active projects at a time, each over a span of six to twelve months. Running them in parallel means insights from one feed directly into another, a discovery on a filter might change how I think about a VCA, or a UX problem on one module reframes a decision on the next.
In practical terms, feedback on the complexity and varied gain and timbre controls in Swell made me reconsider how I’d shape Chernobyl (a timbre-shaping 3-band EQ distortion module due later in 2026). I have a version in testing with musicians now, and that feedback may yet change its direction. Had I launched Chernobyl at the same time as Swell, I wouldn’t have had the chance to let that learning shape it.
But development is fluid, launching a module isn’t. There’s a sequential logic to bringing a product to market that you can’t compress. The most expensive mistake is launching two modules close together when either one still has unvalidated assumptions about workflow, controls, or aesthetics. Rework costs time and money, but the harder thing to recover is reputation.
The habit that’s helped most is keeping a running log for every module with deferred ideas, open assumptions, and all feedback received during testing. When I start something new, I go back through those logs. The reason it matters: when you’re running multiple projects over months, memory fades and decisions lose their context. Without the log, you end up rediscovering problems you’ve already solved, or repeating mistakes you’d already noted. Written down, that experience compounds.
07 Would you say you make things for yourself? How much community influence comes into play with new ideas?
Honestly, Eurorack started as pure personal obsession. The early prototypes were experiments I was building for myself, chasing sounds I couldn’t find anywhere else. But that shifted.
Sharing has always been part of how I work. Long before Eurorack, I was writing about valve design on my hi-fi blog for over a decade — lectures, events, giving knowledge away freely. When I moved into modular, the same instinct kicked in. I began sharing prototypes with musicians I respect, offering modules to help them in their work without asking for anything in return. That generosity pays back in ways money can’t buy: honest, direct feedback from people actually using the thing in a real musical context.
The community shapes implementation with thing such as control ranges, ergonomics, what gets a dedicated knob versus what gets buried. They bring their expertise in what works and what doesn’t from a workflow point of view, which is extremely valuable. But the core direction stays mine. The sonic territory Bartola explores, the decision to use a valve in a filter or other optical components to replace a Vactrol, the choice to embrace non-linearity over pristine reproduction and that comes from my own experience.
The sonic direction is mine; the community makes sure my modules work at their best in practice.
08 How do you decide on the value ranges for the controls or CV inputs on your modules?
Everything starts from my notebook. Ideas turn into sketches and then into a high-level module concept. The process is then iterative by design: simulation first, then bench prototyping, measurements, and (most importantly) actually playing with the thing. At each stage I’m refining the controls, always chasing the right balance between what the circuit needs technically and what makes sense to a musician in the moment.
I developed my own “modular” prototyping system. A bit like the Eurorack concept but at the micro level, inside the module. I have developed over the years multiple small interconnecting PCB blocks, each performing a function (like a VCA, mixer, compressor, etc.). I then interconnect these sub-circuit PCBs to replicate the module I’m working on. That speeds up the process significantly and allows me to add or remove CV control inputs during testing.
The harder question is how many controls and how many CV inputs. Consulting with the community is invaluable here, but there’s a real risk: you can end up with a module twice the size it needs to be because every request feels legitimate. Knowing what to leave out is where experience and judgement take over. It ends up being a delicate art, rather than engineering.
09 Generally speaking, what do your products offer that others don’t?
The specific nature of what valves actually do is where most of the answer lives. It’s not just that tubes sound “warm” – that’s a cliché. What they actually do is saturate asymmetrically, adding harmonic content dynamically tied to the input signal: compressing gently at low levels, warming progressively through the midrange, pushing into organic complexity at higher drives. No hard clipping. Ever. On top of that, there are time-varying non-linearities such as microphonic feedback, cathode temperature drift and that changes behaviour second to second in ways that full mathematical models have never been able to replicate. That’s not marketing; that’s physics. And because every valve is slightly different, every Bartola module has its own character. Two Swell filters will not sound identical.
Valves are just where it’s most visible, the same obsession runs through every design decision Bartola makes or the components I chose to use.
In a market racing to shrink footprints, I design for performance, not efficiency. Every function has a dedicated control – visible, touchable, adjustable in real time. No shift buttons. No hidden menu layers. No tiny screen telling you what mode you’re in. The panel is part of the instrument, not just a label for the jacks.
With my background in cartoons and drawing passion, I also design the artwork myself which is hand-drawn, with a graphic language that’s consistent across the range. That’s part of what Bartola is: a considered aesthetic, not just a circuit board with knobs. To me, the module and brand aesthetics are crucial as they convey and reflect the ethos of Bartola in every element. Striking the right balance between minimalist design and ergonomics is a constant but amazing challenge to work on each design.
There’s a concept I keep coming back to: product plus personality equals brand. Bowie didn’t just make music, he made himself part of the art. Bartola is a point of view shaped by decades of obsession with valves, Argentine roots, a lifelong habit of drawing cartoons, and a genuine fascination with the edge where circuits stop behaving predictably. Very few can replicate that combination, not because it’s secret, but because it’s lived.
And honestly, I’m rarely satisfied with the results. There’s always something I’d refine, rethink, improve. I’ve learned to see that not as a problem but as the engine. It’s what keeps the designs moving forward and keeps me awake at nights!
10 What are some of the challenges in manufacturing, any tips to share?
I’m not a large-scale manufacturer, deliberately so. Small batch gives you the freedom to iterate quickly and maintain quality at every step. But the challenges are real and specific.
Final assembly and testing is one of the harder ones. Because every Bartola module has its own character (the valve variance I mentioned) you can’t just run a batch through automated tests and ship. Each module needs individual calibration. SMD assembly I outsource, but everything else, final assembly, wiring, testing & calibration is done in-house. It’s time-intensive, but it’s also where quality is actually made or lost. Digital modules don’t suffer from this and require so much less effort upon fabrication: firmware upload and quick tests are the only things required. This has a big impact on production costs.
The other challenge that catches most small designers off guard is component availability. When your BOM runs into hundreds of different parts across a growing product range, lead times become a serious planning problem. A single component going on allocation can stall a production run. Managing that, tracking revisions, keeping launched products supportable while developing new ones is genuinely complex. It’s not glamorous work, but getting it wrong is expensive. The perfect example is the Swell launch. I was hoping to release it earlier in the year, however due to just one component, it pushed the launch to the end of June.
The tip? Organisation from day one, not when things get complicated. Document everything, maintain a clean BOM, track every design revision properly, and plan your component purchases ahead of when you need them. Most designers shortcut this early on and pay for it later. I’ve seen it in others and felt it myself. There are great open source tools out there which can help a lot.
11 How do classic instruments and designs influence your own work?
The thing wind instruments taught me that most electronics ignores: expression is continuous. A wind player controls timbre, dynamics, and articulation simultaneously through breath and embouchure in real time, never quite the same twice. MIDI never sat right with me because it reduces all of that to discrete steps. That shapes how I approach Bartola’s control design: CV that’s continuous, responsive, tactile. The goal is to give the player something closer to an instrument voice than a patch point.
Frippertronics opened something different, the idea that sound could evolve and build on itself over time, that texture could become musical through layering and feedback rather than melody or rhythm. Fripp’s tape loop system created a living, breathing drone that you could shape but never fully control. That’s the territory Swell was designed to inhabit.
The third influence is less obvious for a modular context: classic hi-fi valve amplifier designs from the 1950s and 60s. The circuit topologies developed by designers like Williamson established how valves could be used with elegance and precision. I spent years studying and building these circuits before ever touching Eurorack. That lineage is what I bring into modular synthesis, not just the components, but the design thinking behind them. Musicians like Jimi Hendrix understood this instinctively – the valve amplifier’s feedback and saturation weren’t engineering failures, they were the sound. Most Eurorack makers reference Moog or Buchla. Mine reach further out into hi-fi, into circuits that were never designed for synthesis at all.
12 Do you find inspiration in areas outside of the one you work within?
My mind is restless. I read and explore a lot, history, science, philosophy and I spend countless hours with vinyl on my hi-fi. Listening to a full record, both sides, studying the cover art and lyrics is something I find increasingly rare and increasingly valuable. It forces a kind of attention that everything else discourages.
The most challenging and rewarding thing I do outside of design is draw with Indian ink, watercolours, minimalist doodles in the style of Saul Steinberg or Quino, the Argentine cartoonist. The discipline of capturing an idea in a few lines, nothing wasted, feeds directly into how I think about Bartola’s panel design. When a drawing works, it opens something in my head that circuits alone can’t.
Sourdough baking, pizza, fermentation generally with beers, kefir, anything that takes time and lives. It connects chemistry, my hands, and a bit of art in a way that feels close to circuit design. And there’s something in fermentation I recognise from working with valves: non-linear, organic, never quite the same twice. You set the conditions and then you let it happen.
Walking is where I do some of my best thinking. I’ll take a notepad to Tooting Common, sit down, and sketch out ideas be it modules, thoughts, fragments that don’t fit anywhere yet. The more I step away from the bench, the clearer the ideas become when I return.
People are perhaps the biggest inspiration of all. I have a close group of friends who are genuinely extraordinary despite many of them being far away from London – across music, art, science, business. The conversations go everywhere. I suspect the relationship is asymmetric: I take more than I give. What they offer is a way of seeing things I wouldn’t reach alone, and that keeps finding its way back into my work.
13 What would you do if you weren’t designing and making gear?
I’m a creative person and I like not knowing the answer to this question otherwise I’d be doing it already. Anything that pushes me out of my comfort zone, teaches me new things and opens up new experiences, I’m open to it.
I’d push myself to be a cartoonist (black and white Indian ink on heavy paper) hopefully collaborating with musicians to bring music and doodles together.
14 Whose equipment besides your own inspires you and why?
I love Jason Lim’s Instruo the panel design, the workflow, the balance between complexity and accessibility. He’s solving some of the same problems I care about: how do you make a module that rewards deep exploration without punishing the player with hidden functions? That shared sensibility is rare.
Beyond that, I find it hard to single out one maker deliberately so. I’ve bought hundreds of modules over the years, and each one is a form of research: what does this circuit actually do, where does it surprise you, what would I have done differently? Eurorack’s variety is unmatched in that sense. You can hold six different answers to the same design question in your rack simultaneously.
15 What was the last product you created?
Swell (https://www.bartolainstruments.com/product/swell/) — a 14HP valve harmonic filter, launching at the end of June.
The concept started with a Soviet Cold War-era military sub-miniature valve I’d been working with for a long time in hi-fi pre-amplifiers. These were built to military spec designed to survive environments that would destroy conventional components and they have a character that reflects that. Putting one actively in a precision analogue signal path felt like the right kind of provocation. They are also very low power and work with relatively low voltages, which make them ideal for Eurorack systems.
Swell is built around a 24dB/oct four-pole filter with full control over where and how the valve shapes the sound: mode, bias, gain, and placement in the signal path. That last point matters, the valve’s position relative to the filter changes the character of everything passing through it.
The personality is split like Dr. Jekyll and Mr. Hyde. In one mode, compressed warmth: the kind of saturation that makes a sound feel closer, rounder, more present. Push it with FM feedback or resonance, and it transforms entirely. Untamed, harmonically complex, unpredictable. It also self-oscillates as a VCO with 1V/Oct tracking so the filter itself becomes a voice, shaped entirely by the valve’s non-linear character.
Each module is calibrated individually. And because every valve is slightly different, every Swell has its own personality. That’s a feature, not a flaw.
16 Rather than ask “what’s next?” Where is your current inspiration and thinking for your future?
The thread I’m most excited about right now goes back to wind instruments. I’ve been fascinated for years by what a saxophonist actually controls – breath pressure, embouchure, resonance, all simultaneously and how that produces an expression that shifts second to second in ways that feel alive. Electronics hasn’t fully captured that yet. I love to see artists and makers like Konstantine and his Croack module, the direction he’s taking is very aligned to what I have in mind. I’m exploring complex oscillator designs that model some of that behaviour: non-linear feedback, time-dependent responses, elements that give an oscillator something closer to a voice than a tone. It feels like unfinished business from my “electrified” saxophone days.
Running in parallel is the optoFET work where I am developing alternatives to Vactrols using new opto-devices that behave similarly to the original CdS cells, including the memory effects that made Vactrols so musically compelling. These are a completely different kettle of fish which have their own nuances and complexities to work with, something I’ve discovered over the years. I’ve already built a VCA and an LPG using these, both due later this year or into 2027.
The bigger direction is hybrid instruments not just modules within a rack, but things that blur the line between modular system and purpose-built instrument. Combining analogue circuitry, vintage component character, and digital platforms into something you could play as a complete voice. That’s where my thinking is sitting right now.
There’s a lot of unresolved territory in all of this which is exactly how I like it.
17 What’s a piece of music you’d like us to check out?
Fripp & Eno’s No Pussyfooting from 1973, two sides of vinyl, predates ambient music as a genre. Fripp’s guitar fed through Eno’s Revox tape loop system, layered until the original source is unrecognisable. What you’re listening for is how the texture evolves beyond either player’s intention, patterns that emerge from the system itself, not from composition. Put on headphones, give it the attention it demands, and start with side one. It’s the closest thing I know to what I’m trying to make Swell do to a signal.
Coincidentally, Fripp has just released a version of The Heavenly Music Corporation with illuminating commentary about how the whole project came together from the encounter, the relationship with Eno, the recording itself. Worth checking out:
Robert Fripp – The Heavenly Music Corporation (RF@80, Vol. 4)
18 What is something unrelated you’d like to mention for people to check out or be aware of?
Quino the Argentine cartoonist. Most people outside the Spanish-speaking world haven’t encountered him, which is a genuine loss.
Start with Mafalda, his comic strip from the 1960s and 70s: a young girl asking the questions adults have stopped asking about conformity, peace, bureaucracy, the gap between how the world is and how it should be. Written fifty years ago and still sharp enough to cut. It’s been translated into dozens of languages and rewards the investment.
But his other work is where the craft becomes something else entirely. Single drawings, often without a single word, that tell a complete story that’s sometimes absurdist, sometimes devastating, always precise. Three ink lines doing the work of a paragraph. Look at one for long enough and something quietly rearranges itself in how you think about visual economy.
He influenced how I draw. Which means, in a roundabout way, he influenced how Bartola panels look.
Start here:
- Mafalda: https://www.quino.com.ar/mafaldaenglish
- Quino’s humour: https://www.quino.com.ar/quinohumour
- In English: https://jrmora.com/en/the-other-quino/ , check Amazon and other booksellers
19 What’s a question you wish I had asked?
“Where do you get your inspiration for module names?”
There’s no system. Names don’t come from a naming session or a shortlist they accumulate through living.
Throughout my days I’m reading, watching, stumbling across things. A word, a situation, an idea lodges itself somewhere without obvious reason. Then months later I’m deep in a circuit design and something connects the word and the module find each other. It’s less like naming and more like recognition.
Chernobyl is the clearest example. I’d read a couple of books about the disaster and watched several series and documentaries and I was genuinely absorbed by it. What moved me wasn’t the spectacle. It was the specific texture: radiation invisible and unstoppable, enormous complexity made catastrophic by a cascade of small errors, bureaucracy and human fingerprints all the way through. When I was developing the distortion module, something that saturates and layers and pushes a signal into irreversible complexity, the connection was immediate. Chernobyl isn’t a reference to nuclear disaster for its own sake. It’s shorthand for a very specific kind of character: uncontrolled energy, cascading consequences, something that changes whatever it touches.
That’s the test every name has to pass: is it genuinely relevant to what the module does, and does it connect to a real experience I had? If both answers are yes, the name stays.
Swell came from a late-night session where a sound kept building like an ocean wave.
Larking came from a Sunday afternoon lying on the grass with my daughters. The process is always the same, something happens, it sticks, it waits.
And honestly the more I think about it, the less I want to define this process any further. I’m afraid that if I do, I’ll take the magic out of it.
20 To end the questions here’s one from the previous guest
Nick from Infrasonic Audio / WMD asks “What is your spirit animal and why?”
and what’s a question you’d like me to ask the next guest?
A Lark, specifically a Skylark. No two sing identically, each one evolving its own song over a lifetime which is how I think about every Bartola module. Shelley described the skylark’s song as ‘profuse strains of unpremeditated art,’ which is about as close to carefree patching as literature gets.
A few weeks ago during an unusual London spring heat week, I took my daughters out for the day. We laid on the grass in the park and we noticed several Skylarks flying around and singing the most complex and extreme tunes. It fascinated me for a while and thought: I need to name a module based on these amazing creatures: I’m quietly planning a VCA module called Larking, so the spirit animal may end up on a panel sooner than you’d think.
Question to ask for the next guest:
Has a module ever done something you didn’t design it to do — and did you fight it or follow it?
Thanks to Ale for taking the time to answer our questions while sharing his background and experiences with us. You can check out other 20 Questions series interviews HERE and watch out for new ones in the future.
