When I called him a couple days before my studio visit, Shawn O'Sullivan described his setup as "cheap pedals and expensive modular gear." Add to that a couple of drum machines, spring reverb units, three or four highly coveted vintage synthesizers and a high-end audio interface, and you've got a pretty good sense of his inventory. The focal point of his home studio is the Eurorack case full of modular gear, a 22-inch-long box that "can do more than everything else in the studio combined," he told me. It did much of the heavy lifting on last month's album, Fit For Purpose, recorded under the moniker 400PPM, which balances a stern techno ethic with a kind of wild-eyed, freewheeling energy.

People talk about modular synths like a gambling habit. Be careful, they'll tell you, or you'll end up buried in credit card debt, all because you couldn't stop buying shiny little boxes with knobs on them. O'Sullivan, who works at the Brooklyn synth shop Control, has a direct line to the source, and like any modular obsessive, he never stops swapping modules in and out of his setup. The format keeps things interesting for him, in the sense that it's as improvisational as live music gets—meaning it's also a lot less predictable. His solo shows are always ad-hoc, with no predetermined set list or sequence of patterns to guide the arc of the performance.

His recordings are less off-the-cuff, especially depending on which projects you're talking about, from the overblown textures of Vapauteen to the more austere contours of his duo Civil Duty, with Beau Wanzer. Until about 2012 he also played with the cold wave revivalists Led Er Est, and now records and performs alongside his wife, Katie O'Sullivan, as Further Reductions. They live together in a cozy apartment in Flatbush, Brooklyn, where their home studio shares space with a wall of records and a bed. I hopped the train down south last month and we spoke for nearly three hours, over tequila-sodas, about the ins and outs of modular synthesis.

How did you get into modular?

I got into Eurorack about five years ago. Some friends had been encouraging me to go in the modular direction for a little while, and the final push was when my friends Jonas Asher and Daren Ho were opening their synth shop, Control, in Williamsburg. To fund my initial jump into modular I sold about 1,200 records out of my collection. A bunch of it I actually sold to Ron Morelli over at A1 Records. He came over and took about six or seven hundred records.

Did you find it intimidating at first?

I'd been making music for almost ten years at that point, so I had a solid understanding of synthesis and signal flow and stuff. So it wasn't daunting getting into it. There's a few things you have to wrap your head around initially, but if you have a decent understanding of signal flow, and a decent understanding of synthesis, it's not that technically difficult. The big problem is just the upfront expense.

If you google "modular synthesis," the first thing that comes up is people asking where to start—what modules to buy, what combinations and configurations are best for beginners. What was your initial setup like?

I remember buying Make Noise's MATHS—it's one of the cornerstones of Eurorack. It's a great module. At the shop I suggest it to everyone who's starting, basically. Not just because it's a really good module, but because I think it's a spectacular learning tool. All it does is make voltage that goes up and down. That's it at its core. And then in the middle there's two channels that can scale and invert that voltage. It sounds pretty banal, but once you wrap your head around what this thing can do, then the rest of all of it makes sense. I think even just as a learning tool it's absolutely indispensable.

What are some of the resources available to someone who's just starting out?

When people ask me that, I tend to tell them, "Well there's this forum Muff Wiggler. It's really unfortunately named, and it's kinda shittier than Reddit—but there is good information there." Especially five or six years ago, they were really one of the better resources for finding out about Eurorack stuff, and there are a lot of threads in there like "starting configurations," or "budget configurations." Admittedly it was a pretty valuable learning tool for me initially, mostly just in terms of learning about the different manufacturers and what was out there.

The other thing to mention here is, when people talk about getting into Eurorack, one of the things we do at Control—which I really generally consider a public service—is giving people access to all this stuff so they can come in and play with different modules. Often someone will say, "I want this module, I saw this demo," or "so-and-so uses it. It's sick." And I'll help them patch it up, demonstrate it to them, and they'll be like, "Actually, I dunno." Then I'll suggest something else, like, "Well, try this filter," and they'll end up liking that one way better. A lot of times the modules don't do quite what they're advertised as—sometimes in a good way and sometimes in a bad way. Trying this stuff in person is pretty important. Five minutes of hands-on time is way better than a thousand YouTube demos.

My understanding is that part of the appeal with modular patches is they never really sound the same twice.

Some digital models do have memory that allows you to save stuff. But generally you're never gonna get a patch back exactly the way it was. Even if you have a patch that's essentially identical, it could be a totally different thing.

Is that part of the fun of it?

Oh, absolutely. A lot of people talk about modular synthesis as if it opens up infinite possibilities, but I think of it as the opposite. It's something that narrows possibilities compared to a digital environment. Obviously you want a configuration that's flexible, but at the same time you want to limit your pallet. You want to limit your capabilities, and I think lacking features that are super basic in a digital environment—that's a really powerful and really vital limitation. For me one of the most painful things is having to do the same thing over and over again as a performer or a musician. It's terrible, the idea of having to go on stage and do something you've already done before. Why would you do that? Why would you do that to yourself? It's just not fun.

What are some of your essential modules?

As far as basic analog oscillators, I really like the Bubblesound VCOb. I have three of them here. Dave Wagenbach, who designed them, is a local guy. His modules are great—they sound good, they're affordable and they have a good footprint. That's something to mention, too. In Eurorack, obviously, money economy matters, but the spatial economy of it is very integral to how you configure things. When I first began to really understand Eurorack, it was like, "Oh shit. This is Magic-The-Gathering-meets-synthesizers. This is going to be very bad for me." Because you have this collector aspect to it, and you're thinking about all the combinations you could have, but then again you only have so much space in your rack.

There's a common discourse around modular like, "Don't go too deep, you might never come out." Where does that come from?

There's a couple of things to be wary of. One is I always advise people to go for a little extra space when they're choosing the architecture to house it in. You should always get a little more than you think you need. Because once you get into it, you're gonna want more space, and you want certain things to work together. But at the same time, if you have too much space then there's this obligatory need to fill it.

The other danger is that people stop making real music. And "real music" is obviously a really problematic term, but I mean it in the broadest sense. When people go down the modular rabbit hole, they stop making music, they stop producing music, they stop finishing music. Because it just becomes, "Oh, I could do this patch, and then this patch," and it becomes more about the patch than the result.

It's like when you're a jazz guitarist and all you want to do is play intense modal scales.

Exactly. Like, "I can do this patch and it's totally crazy. Did you know you could use this module as an oscillator?" And it's like, well you can, but you probably shouldn't cause it doesn't work. Or I guess it kind of works?

What do you like about the format?

Its flexibility and portability. And also just scale. I have more in this case than everything else in the apartment. If you don't have the luxury of a gigantic studio, and if it's something you want to travel with and play with, then ultimately this is actually fairly economical. Yes, it can be prohibitively expensive if you're just starting out making music, and you definitely do not need $10,000 worth of modular to make great music. But at the same time, to deny the flexibility and the immediacy of something like this is also kind of narrow-minded.

When we talked on the phone earlier you expressed some frustration with the current status quo when it comes to so-called live sets.

Just because you have a bunch of gear on stage doesn't make it any more "live." There are laptop sets that I've seen—or a laptop plus one or two small pieces of gear—that are way more live and way more organic than a lot of sets with modular, or with a whole bunch of gear on stage. People can show up with everything pre-sequenced and it can be fundamentally no different than someone doing a live set where everything is just Ableton stems. That's something I like to avoid, because I don't like really any aspect of playback. I would probably be a better live act if I embraced those things, but I can't and won't. Because it would defeat the point for me.

I do want to provide an experience that people enjoy dancing to. I like playing dance music. I like seeing people dancing. That's also why I make techno, because it's more of a blank slate than almost any other kind of popular music genre. It's super flexible, in the sense that you can put whatever you want in the box, and take whatever out. And formally it's very suited for live improvisation. One of the things that drove me in this direction with modular stuff is it's great for live improvisation within techno.

Do you tend to work with the crowd in terms of reacting to what they're feeling and not feeling?

Absolutely. I try to read the crowd as much as I would during a DJ set. If the energy is dipping, then maybe I'll bump the BPM up two or three. If I feel like I'm losing people's focus, maybe I'll try to bring in a melodic element. And also, how I play is also very dependent on the soundsystem in the physical space. Generally, I go in during soundcheck to see what the space is like first and foremost, to feel what the soundsystem is like, and then I can approach things from there.

During soundcheck I'll start out by programming the bass, and then I'll make sure I have enough material to work with for the first five or ten minutes while I feel things out. Because let's say I had prepared a pretty ambient melodic set, or an acid techno set or something, and I go in and the space is not suited for it, or the sound is not suited for it, or it doesn't feel like the crowd is going to respond to that—if I was locked into doing that then I would feel limited. Appealing to the crowd and the space is definitely a concern for me.

Can you explain your songwriting process?

When I record I kind of have two broad approaches. The first is more of a technical thing, like an idea for a patch, or for some kind of processing, like, "I wanna run this instrument through a pedal." Or it can be something as simple as wanting to rip off a song, and it's never a clear line from there. For instance, on the album there's the track "New Exploration," the one that Katie did vocals on. That one was me wanting to do something that has the feel of Chrome, the band. They're like a late '70s synth-punk, or kraut-punk band from San Francisco. They're really hard to categorize in any specific terms, but they're one of my all-time favorites, and an influence that I always tend to draw on.

In another interview you said you had three or four techno LPs that never came to light. I'm curious, why did this one make it out and none of the others?

A few different reasons. Mostly I'd record a bunch of stuff, and I'd be like, "Is this an album?" And it wouldn't really feel like an album. Then it would become an EP, or maybe some tracks here and there, and then a month or two would pass, and if I were to do any more work on it, it would feel disjointed. Everyone's process is different but for me, I'm most comfortable with an album when it's a snapshot, when it's a picture of certain processes, both technically and otherwise. Once you're out of the headspace that was happening in that moment, there's a discontinuity there.

So it all happened in a few sessions.

Yeah. I can't remember exactly how many sessions, but probably five or six.

How would you describe your workflow?

Mostly I just set aside as much time as I can to record and generate as much material as possible. Then I kind of piece things together from there. For me at this point, I'm not the kind of person who can record for an hour or two after a day of work. That's not very rewarding for me. I wish I could, because I'd be more productive, but for me as an artist, I feel like quality comes from quantity. I get my best stuff in after I've just recorded a ton of shit.

Once you're loosened up?

Yeah. But I also have to work through ten bad ideas before I get to one good one. I don't do well when I have to linger over one track. "What can I add to this?" "What is this one missing?" "This is going to be my masterpiece." I don't work that way. And again, there's no value judgement there. Plenty of people work that way, and that can be a great process. But for me, I need to generate a lot of material to gauge what is and isn't working.

You also mentioned that you wanted to avoid the typical techno album format of five bangers, three deep cuts and two ambient tracks. How did you mitigate that?

The first thing I did was set a ground rule that I wasn't gonna do an ambient track. It's a shame that that's become such an obligatory staple in the genre. Also because, generally speaking, techno musicians do not make very good ambient music. There are exceptions of course. But you know, it's frustrating that that is such an obligatory narrative stop-gap.

Was there a certain balance of energy levels that you wanted to hit across the whole album?

After everything was recorded, actually, I realized the album was missing one more banger. So I did feel the need to have something else there, but that was for overall narrative purposes as much as it was for functional ones. That track, "8.069," was my explicit nod to Regis. I don't know to what degree that translates, but I felt like it needed another explicitly floor-functional track, so I filled that in kind of last minute.

Would you say that you're a perfectionist?

No, I love imperfections. Again, for me, I like generating volume and trying to embrace the accident as much as I can. If something doesn't work, I don't labor too hard trying to make it work. I just accept that it's not working and move on.

What about with mixdowns and post-production?

I mean, I'm half deaf at this point in my life. I've done very dumb things to my ears. So I do what I can on the engineering side of things, but I accept that as a limitation as well.

Can you tell me about this Lynx Aurora audio interface here?

That really was one of the key pieces in this album coming together. I had an RME interface for a few years, which was really good, but it had eight channels, which isn't quite enough, especially when I'm working with someone else. I also had this Focusrite interface, which I was using with the RME to boost it up to 12 channels, but it was still kind of limiting.

I was thinking through all the possible ways to get more channels, and Phil Moffa, who is a totally brilliant studio guru, was helping me troubleshoot. After brainstorming with him on a huge email chain, he was like, "Dude just get a Lynx Aurora. Just do it." I was really happy with that, not just because I get 16 channels, but because the fidelity is great and the convertors are super, super high quality. It was absurdly expensive, though, and I had to sell off a bunch of gear to fund that.

What's the importance of having high-end convertors?

You're capturing more of the frequencies. I'm no tech wizard, so I can't explain things in much more detail than that, but basically when you're recording with shitty convertors you're losing frequencies. And when you're losing something in the 40 hertz range or whatever, you can't get it back. I want to capture what I do in the highest fidelity as possible, and from there I can mangle things a bit if I want. Even when I want something to sound like mud going in, I want control over that.

How much of your studio is vintage versus new gear?

I love vintage stuff, it's just it's so expensive. And I know that sounds ridiculous coming from a moderate Eurorack addict but you know, SH-101 synthesizers are going for over a thousand dollars these days. That's only four oscillators in Eurorack language. With Eurorack, you can spend under a thousand dollars to build a full synth voice, except you get at least one oscillator, a filter, a VCA, and some kind of envelope generator. Why get a vintage MS-20 when for $2,500 you can get a nice Eurorack system, or for $250 you can get a used MS-20 Mini, which sounds 80-percent as good?

It gets worse when you talk about the vintage poly synths. I've got a Juno 60 over there, and there's a PolySix over there, then there's the Prophet-5 that my friend gave me. Basically I got all of those for cheap, and I would never advise anyone other than the independently wealthy or spectacularly trust-funded to invest in a vintage analog poly synth. Just because, you know, you're spending one, two, three, four, ten grand. Jupiter-8s I think are over ten grand now.

How do you think the vintage synth market got so warped?

I don't have an easy answer there. Vintage synth prices have been steadily climbing since the early 2000s or late '90s. I read something once that said somewhere on Wall Street, someone identified the vintage synth field as a potential growth market—worth investing in. It's possible they're all being bought up by hedge funds for all I know. Like everything else in this fucking city. I don't think that's actually the case, but I wouldn't be shocked if it was. And you know, eBay drove prices up for years, too. It's the same with any kind of bubble like that, like what's happened to record prices since Discogs hit the market. And not just for old stuff—now you have records that are six months old selling for 200 euros.

Because they only pressed like 50 or a 100.

Yeah, they're deliberately scamming the market. And then they're all bought up initially by speculators anyway. And not that these people are making crazy money or anything, but you know, it's turned into a weird speculative bubble. And Discogs is particularly nasty in that regard. I do think to a degree people know analogue synths are safe to invest in.

It's weird to be talking about all this stuff in terms of market risk.

Well, you know, I think when you're talking about technology, you should always be aware of that.

There's still a lot of good stuff you can get as far as late '80s or early '90s digital stuff. There's a lot of cool romplers that are pretty underpriced, a lot of digital drum machines that are fun and weird. The Korg Poly-800 is actually an analog poly synth, and those are still pretty underpriced. Does it sound as good as a PolySix original? No, but it is analog, and it has its own characteristics, and it's cheap. If you do want an analogue poly synth, you can find one cheap.

Do you ever record instruments live in a more tactile way? Like, banging something out on a drum machine or playing a synth line?

With Led Er Est I played a lot. I'm not very good, but I can play a chord at the right time.

Or a single note bassline.

Yeah, exactly. "Derr derr derr derr durr durr durr"—I can handle that. I haven't done any of it in my solo work, I mean as a live performer. And there are times I do want to. It'd be nice to bring in a lead, and there are definitely people who can do that really well. But generally the palette, when I play live solo is pretty—I don't want to say narrow, but melody isn't generally the focus. It's more texture, repetition and rhythm.

Do you make music with the idea that it would work in one of your DJ sets?

When I DJ I don't usually play any of my own stuff. When I played on The Lot Radio recently, I played two of my tracks back-to-back, which was the first time I'd ever done that. It felt very indulgent.

The radio's the place to do that.

Yeah. I played my remix for Wata Igarashi into one of the tracks from the album and it sounded good. But to a certain degree, my own stuff is a little hard to work into DJ sets.

Well somebody's doing it. They're buying your records.

Only hedge funds are buying my records.