Stephan Thelen: Of Sonar, Fractals And Interactive Complexity

If you have been at all aware of the two-decade-old movement known as Swiss Minimalism, you've likely seen Stephan Thelen's name crop up. Lately, it would be fairly difficult not to. From 2018 to 2023 alone, his work as a leader in groups like Sonar and Fractal Sextet along with his Fractal Guitar series and other collaborations have produced no less than 12 albums—with at least two more pending releases at the time of this interview. Even more noticeable is that as his output has increased, the American-born, Swiss-based guitarist/composer/mathematician has garnered more and more critical acclaim, challenging the age-old equational validity of quantity vs quality.

Stephan Thelen sat down with All About Jazz in the Spring of 2023 via Zoom from his home in Zurich.

All About Jazz: You are American-born, correct?

Stephan Thelen: Yes. My parents were from Frankfurt Germany. When my father was studying physics, an American businessman invited him to come work in Santa Rosa California. So I was born in the States when my family moved there in 1959. I grew up there until I was ten when we then moved back to Europe. I went to school in Switzerland studying math and music and I've been here ever since.

AAJ: How do you see yourself, American or Swiss?

ST: I enjoy my American background, I have a lot of American friends and certainly like America but my mindset has always felt more European, so yeah, I consider myself European.

AAJ: You touched a little on your father being a physicist and you being a mathematician as well as a musician. Do you consider mathematics your vocation or is it music?

ST: Well, I was always good at math. When I finished school at 19, I talked to my father about my further education and said I would like to be a musician. He basically said, "Oh, don't go there. You'll starve." (laughs) So he said it was ok to do music but I should have something on the side. So the other thing that did interest me was math. So I studied math—but I've always done both. I've always had a band and worked on music in parallel to math.

AAJ: What were the musical influences that shaped you?

ST: I think that's an important question. I feel that people are very influenced by the first music that they love. My sister was a little older and had all The Beatles records so I can remember listening to them a lot when I was around 8 or so. Then when we moved to Europe, my older cousin was into prog and was responsible for getting me into prog music. I would visit him and he had Emerson Lake and Palmer, Yes and King Crimson records. I was a big Yes fan for a while, and actually learned and could play everything from Yessongs (Atlantic, 1973). King Crimson was the band that really struck me the most though—Larks Tongues In Aspic (Island, 1973), Starless And Bible Black (Island, 1974), that era.

One time Crimson was playing in Frankfurt—it was the band with Bill Bruford and John Wetton, like 1972—and I wanted to go but my cousin said, "Oh no. The new King Crimson aren't good anymore..." (laughs) We didn't go, which I really regret.

AAJ: Well, in light of the music you are doing now, one might guess that the '80s version of King Crimson—with its penchant for poly-metric overlays—had a big influence on you.

ST: Yeah it did, but maybe not so much as you might think. I mean it was the '80s, right? Pink suits, bad haircuts, guitars with way too much chorus, cheap electronic drums and synthesizers, etc. For my ears, the overall sound was too slick and feels very dated in retrospect. They were also trying to be more entertaining, and for me, King Crimson wasn't about entertainment, it was serious stuff. I did like a lot of the polyrhythmic ideas but for me, it's the grit and searching spirit of the '72, '73, '74 band that I really like.

The polyrhythmic stuff actually started [as an influence] through things like Steve Reich and also Bela Bartok in classical music. Then later on, (Swiss minimalist pianist, composer and Ronin bandleader) Nik Bärtsch basically lived around the corner from me in Zurich and I saw him in the very early stages when he was not known to the jazz scene in Europe. He and I ended up talking about polyrhythmic concepts and things quite a lot so actually, that influence came into my music a bit later. I can hear there are some of those things present in my music from the '80s when I listen to it today but not polyrhythms so much as odd meters.

AAJ: So you knew Nik Bartsch early on. Were you also aware of (saxophonist) Don Li as the Swiss Minimalist movement was forming and gathering steam?

ST: Well, Don and Nik played together for a long time and I knew both of them. The thing was, I'm a little older than they are—by like 10 years—and I was not really part of "the scene." I was somebody that they knew but not someone they engaged with as part of their bands. I did see a lot of their concerts, going to Bern often to see Don and seeing Nik in a lot of small clubs and coffee shops.

AAJ: Did you ever consider yourself a part of that movement?

ST: No, I didn't feel like I was a part of the movement per se. There were lots of ties, to be sure. For instance, I know (Sonar drummer) Manuel Pasquinelli because he was in one of Nik's workshops. I also had a band for a while with (former Ronin bassist) Bjorn Meyer. But if there was a book on Swiss Minimalism, there might be a chapter on me as an aside—nothing like there would be on Nik Bartsch or Don Li.

AAJ: In addition to solo projects with guest musicians, you have a lot of actual solo recordings in your back catalog. Did you perform this music—either solo or as a band—during those years?

ST: Yes, we did perform a lot of that material but they amounted to only a few concerts here and there, not dozens of shows. I also played in a rock band for a time called Radio Osaka. It was a quartet with a singer. In that band, I played a lot more guitar than I generally do now. I guess you could say I was a guitarist mainly back then. Now I consider myself more of a composer, arranger and producer that plays guitar, but not really a soloist. I would rather invite David Torn, who does such a good job I don't even need to play. (laughs)

AAJ: In reviewing a lot of your early material—which ranged from solo guitar to band outings to ambient/textural and metric explorations—it feels as if Sonar was a kind of culmination of things. Can you talk a bit about the genesis of Sonar?

ST: Sonar was a turning point for me. I had [previously] done all these albums and concerts and we had gotten good reactions to everything and it was all fine but it wasn't going anywhere. So I thought that if I'm going to do something, it has got to be special—something I have never heard before.

I remember saying to (fellow Sonar guitarist) Bernhard Wagner that we really have to find something new—new ideas about how we want to play together, new approaches. I thought back and I remembered there was one piece I had played that I couldn't play in the standard tuning so I retuned the guitar to tritones [intervals of a diminished fifth that divide the octave evenly in half]. Bernhard and I tried this tuning together and then Bernhard started playing all these harmonics and suddenly it made sense. This is what we have to do.

We decided to do other things as well. We would play straight, with no effects. We wanted the music to be very polyrhythmic, etcetera, etcetera. We had a few ideas and they all seemed to work. It's well-described in (music journalist) Anil Prasad's liner notes for our album Static Motion (Cuneiform, 2014). We also had a lot of help from Nik Bartsch. He put out our first album and one of our first concerts was at (Bartsch's venue) Exil. We had a lot of what we considered to be success with that project.

AAJ: Well, in terms of forging a sonic and musical identity, it certainly seemed so.

ST: Funny enough, Sonar was never really that successful in Switzerland. We never got the kind of response there that we had in England, Germany and the U.S.A. Those were the countries where we got the most feedback.

AAJ: After Static Motion, Sonar made another leap with the decision to bring David Torn on board. How did that come about?

ST: I was in California visiting Anil, and he and I went to visit Henry Kaiser in Santa Cruz. Henry's such a great guy. I love being at his place with all his guitars and he's a fantastic cook as well. Anyway, I asked Henry, "If Sonar were to have an outside producer, who would you suggest?" and he said straight away, "David Torn." For me, that was great because I knew David from his ECM recordings and loved those records. So he put me in contact with David and that's how that happened.

The initial idea was that David would produce but then when he was coming to Switzerland, I asked him if could bring his guitar and maybe play one or two tunes with us. So he did and we went into the studio. We recorded the first piece and Anil, who was also there, suggested that David overdub on the mid-section of the piece. When he did, we loved it so much we said, "C'mon, let's do a take with you, as a quintet." Well, when we did that, it was phenomenal. The four of us playing together had a very high energy level, but when David joined in, it just blasted it open. The energy, you wouldn't believe it.

Then Anil said, "David, you have to play on every track." And David said, "Oh no, I can't do both. I can't play and produce. It's too much." but eventually he did, so...

AAJ: In retrospect, adding Torn to the band as a player does seem like an inspired yet almost obvious recipe for explosive potential—the sonically austere and often sublime polyrhythmic interactivity of Sonar receives an anarchic X-factor injection. It's all so highly complementary.

ST: You know, a lot of people who saw Sonar before said that it was a great band but something was missing—a voice, a saxophonist... something, but I didn't really want any of those things. But David Torn, that's something else and it really worked out well. You still get those people who liked Sonar better before David, when it was more minimal. You can't make everybody happy. (laughs)

AAJ: As we speak, you have another Sonar album featuring David Torn coming out, correct?

ST: Yes. It's finished and I must say, I feel it's a really great album. We [Sonar] had not played together for about a year and a half because of Covid and everything so the four of us got together and decided it was time to do something new, but I had no idea what I wanted to do.

I tried some ideas but then decided that instead of composing pieces and bringing David in to play on them, I wanted to start with David's solo pieces or loops and compose on them. So I asked David to send me some new pieces and I used those as the starting point for the new tracks. I took short sections out of his pieces and sampled and looped them in some cases.

Some of the tunes are very long. The first track is 16 minutes; the second is 11 minutes and the third is 15 minutes. So the whole album consists of three long pieces. I feel like it's not three unconnected pieces on the album but one whole piece of music in three different sections—like a symphony. That's why the album is called Three Movements.

AAJ: Did David Torn play live with Sonar in the studio again for this album?

ST: We used the samples of David as the basis and the quartet played on top. Then I sent the tracks to Jan Peter Schwalm, who put some really nice synths and electronics on it and then David came to Switzerland and recorded his parts over two days. That was really something. He set up his tube amps—a Fryette and a couple of twin reverbs—and cranked up to a volume you wouldn't believe. It's very gutsy, with a lot of feedback. Great stuff and I've never seen him so relaxed. David spent the week at our house and it was such a good vibe.

His playing in the studio was really phenomenal—especially on the third piece. The third piece is something I really can't understand. I hear it today and it's a piece of music that I really don't know where it came from. There's a climax at the end that is unbelievable. So much power that I have never experienced before. The album will be out in June of 2023.

AAJ: You have been extraordinarily prolific over the last few years. It seems to have started around the time of Torn's entrance into Sonar and continued with the release of your Fractal Guitar series of albums, the first of which earned a five-star rating from AAJ's own John Kelman (see the review here.). What was the genesis for Fractal Guitar (Moonjune, 2019)?

ST: Fractal Guitar started because I was with Markus Reuter and he asked me if I wanted to do a record together. I said, "Yeah we could but what if I do an album and you play on it and co-produce it with me?" The first album took me a long time to finish. I actually started gathering stuff for that around 2015 and finished it in 2018.

Work on Fractal Guitar II (Moonjune, 2021) started when I was in California recording tracks with Henry Kaiser and friends in November 2019, right before the pandemic began. Funny, I really like II because I liked my life during the pandemic. (laughs) I love to be home. I love to work at home. I had just met my wife and we were really in love and had three new cats—my life was wonderful.

One of the main driving forces for Fractal Guitar III (Moonjune 2022) was that I was really looking forward to working with Eivind Aarset and what we could do together. He is a really phenomenal guitarist. He's so creative and can make the most amazing sounds. His feeling for what a song needs is really great but he also gives you a lot of choices. I would send him a track and he would send back seven guitar tracks—and they were all great. I got to choose which one I liked the most. We also have Yogev Gabay on two tracks and Jan Peter Schwalm is on Fractal Guitar III for one track. I also sampled some bass tracks laid down by Tim Harries for the record.

AAJ: You've always put out a variety of music from textural and ambient to meter and rhythm-centric. The Fractal series of albums seems to have brought a much more cogent vision of your textural side in a similar way to how Sonar seemed to gel things on the metric side. How did your compositional approach change for Fractal after finding a voice within Sonar?

ST: Well, Sonar started in 2011 and for four or five years I did nothing else. We did a lot of concerts and recorded those albums. Then a lot of things happened around 2015. I got to meet David Torn. I played with Markus Reuter. And for five years I had played without effects so I felt like it would be nice to break out my effects rack and explore that a bit. Then, all of a sudden there was this idea to do an album with a lot of effects and have some fun.

Sonar is not really fun. (laughs) It's more of a serious musical attempt. But Fractal was like ok, let's have some fun, do crazy stuff and really kick ass. There also wasn't any real stress because I took a lot of time. I have to say that from the beginning to the end, it was pure fun. There were no problems, no agony. In Sonar we had a lot of discussions about whether to do this, this or this. There was none of that in Fractal. Everything was just like on wheels so it was a very good working experience for me. Also, I may be the main composer in Sonar but the other guys have their ideas too. It's more of a group thing and required discussions.

AAJ: So let's talk about Fractal Sextet (Alchemy, 2022). Maybe it's because the previous Fractal releases were ostensibly solo projects with guests and this is a band project, but in many ways, Fractal Sextet feels almost like a bridge between your Fractal projects and Sonar.

ST: Well, the idea for the Fractal Sextet came from talking to Jon Durant who said, "Wouldn't it be wonderful to have a live band to perform the Fractal Guitar stuff?" and I thought that was a great idea. So we started thinking about who could be part of that with the two of us. Jon said immediately that (keyboardist) Fabio Anile and (percussionist) Andi Pupato should be in the band. Then he said he also knew (Porcupine Tree bassist) Colin Edwin—whom he played with in his Burnt Belief project. He thought Colin would be great and he plays differently than probably any bassist I might have chosen.

So suddenly we had five people but we needed a drummer. Colin said he had heard about this guy, Yogev Gabay, who had a YouTube channel and is a great drummer. So I contacted Yogev and asked if he wanted to play and record with us and he said "Sure, I'll come." So he came to Switzerland and we recorded the whole Fractal Sextet album plus two tracks for Fractal Guitar III in the same session.

The Sextet's music, it's something nobody would have ever thought of on their own, really. It just came together from the people who were in the band. Fabio, for instance, is a very strong element and Yogev's style is a very strong element as well. Also, Colin is such a wonderful bassist because he can play very melodically and at the same time hold the necessary groove. Add Andi with his percussion sounds, Jon's lead guitar sound and me just doing whatever else. It was just a unique combination. Listening to our first album today, it still amazes me how six people can just come together like that and create something new. No one could conceive of it by themselves. And the way Yogev plays is like a mystery to me. (laughs) We all fit together in a very special way.

The initial idea was to have a live band do the Fractal guitar stuff. We did do one track from Fractal Guitar that ended up being a bonus track on the digital version of the album. There were two tracks from a duo album that Jon and I did that had no rhythm section. Of the other three tracks, one is by Fabio—"Planet Nine," which is actually my favorite piece.

AAJ: How did you present the material to the band?

ST: The process usually started with me at home with a drum machine, a sequencer and Logic. And of course my keyboards and guitars. Then I would send that to Jon and he would add solos and other guitar parts. Then Fabio would get it and replace my keyboard parts with his keyboards and also come up with many ideas of his own. Then it went to Colin, then Yogev laid his parts down, then finally Andi. That was the sequence. So I did do a demo in the beginning but it changed a lot because as it went around, people would suggest changes and additions to the arrangements. It definitely evolved from where it started with me.

AAJ: The piecemeal aspect of the recording process that you describe is pretty counter-intuitive to what you hear on say a track like "Planet Nine." The drum and percussion break is so ferocious and organic sounding, it doesn't seem plausible that those two weren't in the same room when it was laid down.

ST: Yogev did the drum solo on that track and then Andi did his part afterward. Actually, Andi sent me what he had done initially and it was good but I said, "Andi, c'mon! You can do more than that!" So he did a second take where he played all these runs and everything and that was great.

But Yogev was really incredible too. I've never seen anybody so well prepared. He came into the sessions knowing every detail of the pieces. We did three takes of every piece but the first one was always perfect... always.

AAJ: So are there plans for another record from Fractal Sextet?

ST: Yes, it is being recorded right now. The sequence wasn't quite the same this time because of people being busy. Fractal Sextet II is going to be a little bit different. There are a lot of things going on that I would not have thought would happen. There's actually one song in 4/4. (laughs) That's a rarity.

AAJ: Any plans to tour the group?

ST: We all want to but it's just so difficult to get these six people [together]. Jon lives in Portland Oregon; Colin Lives in London; I live in Zurich; Fabio lives in Rome... [Touring] the States is impossible because of visas and everything. The only place we could play is in Europe but to put a band on the road nowadays; it's so expensive. Maybe some festivals but we're still only just talking about it. I hope it will happen.

AAJ: In addition to all of these pursuits, you composed a piece for the Kronos Quartet which led to a full album of music for string quartet entitled World Dialogue (Rare Noise, 2020). How did that project come about?

ST: I think it was in 2006 I got some computer software that allowed me to emulate string quartet sounds. I loved the sound so much that it inspired me to do my first writing for a string quartet, which became the piece "World Dialogue." It's a piece that Anil heard at my place and he said, "This is great. I'm meeting Kronos next week for an interview and this would be perfect for them." So he went back to the States and played the piece for [Kronos founder and violinist] David Harrington. Then one evening I had an email from David Harrington in my inbox. That was a very nice moment in my life. (laughs) He said he loved the propulsiveness of the piece and would like to see the score. So I sent him the score and then I didn't hear from him for a long time. I wrote to him again and finally he said he got the score and wanted to meet. So we met in San Francisco and he said he loved the piece but wanted me to write a new one, expressly for Kronos. I wasn't sure if I could write another piece as good as that one, but of course I said yes.

I went home and had no idea what I wanted to do so I sat down, found a starting point of an idea, turned on the computer and just played for two hours, working on variations of that initial idea. Basically, the whole piece was already there in those two hours of improvisation. All I had to do is take the best parts out, rearrange them and make a piece out of it. The whole process only took two or three months and ended up being a lot of fun. It turned out to be a great experience and I really liked the piece ["Circular Lines"] and David loved it too. I then met them when they were on tour in Switzerland and we went through the piece. They eventually played it live and then recorded it in San Francisco but it's a tough piece, I'll tell you. They really had to sweat a lot because it's so polyrhythmic, There are always three rhythms going on and one is usually in five—that's the tough one. Three against four is fairly common but having a five against that—that's something that very few people are used to doing. But Kronos loves to be challenged and they really did a great job.

AAJ: Kronos only ended up doing the one piece on the album. How did you get involved with the Al Pari Quartet to do the rest?

ST: A math pupil of mine wrote that she was in Lugano Switzerland and saw that another string quartet was playing "Circular Lines." I was unaware that anyone else was playing that so I Googled them and they were an all-woman group from Poland. I wrote them and said that I would love to hear their version. They were going to be in Lugano for a while so they invited me down there and we had a lovely afternoon. They were all extremely talented and their interpretation was in the same league as Kronos. I mentioned before that I feel more European than American and I think I enjoyed the way Al Pari played it so much because they played it with a very Eastern European attitude.

So we started talking and I suggested that I could write a new piece for them if they liked. They're quite young and were very excited at the thought of someone writing a piece for them. One of the Al Pari members gave me an album of Polish folk songs. One of the passages stuck in my head so I played around with it and altered it some. It only took a few months more and I had the piece ["Silesia"] for them .

AAJ: Have these experiences composing for ensembles outside of the guitar-led band realm changed the way you compose?

ST: For Sonar, I used to compose from the guitar but nowadays it's more from the keyboard. My music is not very complicated harmonically. It's more complicated on a rhythmic level. I can play these polyrhythms better on a keyboard but some of the stuff I can't even play. I have to program it to really hear it perfectly. It varies though; it's both.

AAJ: It would perhaps be easy for the listener to conclude that your mathematics background has informed your seeming fascination with rhythmic patterns and complexity. How do you feel it affects or informs your music?

ST: Well, firstly, it's very, very simple math behind the music. The kind of math you do at the university is way beyond those things that would make it into a composition. A composition only really deals with relationships of numbers and maybe the structure of the piece, so it's actually very simple. [The math,] for me, has a lot to do with the structure of a piece. I automatically think about the structure—how I want to get the parts intertwined—and there's always a plan. It's always about how simple things can interact to make it more complicated. You take three simple rhythms and put them together and get a complex rhythm by combination—if you do it in an interesting way.

AAJ: And your Fractal Guitar projects, there's no underlying mathematics or science in your approach to them, as the title might imply?

ST: Not in a deep way. It's just the idea that if you look at the pictures—the fractals—that were invented by Benoit Mandelbrot in math, there's something going on that obviously has a pattern. It might get smaller or more developed, and so on but it's the same idea—that something has a similarity to other things. It just felt like the right term. It was actually first coined by a member of one of my early bands, who liked "that delay that sounds like a fractal." Not very deep. (laughs)

AAJ: Do you consider yourself a rock musician? Jazz musician? Your music touches both but is also outside the normal realm of both. How do you see yourself?

ST: I definitely see myself more as a rock guitarist I guess. I mean I learned how to play jazz guitar. I learned all the chords and progressions but I was never really into jazz that much. I loved the simplicity of rock. There's a direct energy you get from playing something simple, in a decisive way. That was something that appealed to me more than complex harmony. I never really liked complex harmony; I don't know why.

I read one of the reviews of World Dialogue recently and someone said the rhythmic stuff was great but the harmony was underdeveloped or primitive. My reaction to that was, "Yeah, exactly." That was deliberate. I don't want too much harmonic complexity. So yes, I am more of a rock musician in that sense but I'm also interested in classical music. I also do like some jazz but I'm not a jazz fan, per se.

AAJ: What further musical plans do you have for the future?

ST: I'm thinking about that right now. One thing I'd like to do is something with David Torn. Two guitars and maybe a rhythm section. Kind of centered on the type of playing he did at the recent Sonar recording session—a lot of feedback, a lot of heavy stuff, very rock oriented. I really want to do that with him. He's such a great guitarist. There are a lot of good things out there by him but there are a lot of things that he can do that no one has ever heard. I want to tickle more of that out of him. (laughs) In general, I don't think I'm going to be getting more and more extreme, staying on the same path. I'm going to be opening up to other things as well.

AAJ: You have had such a voluminous output recently. Do you ever wonder where it all comes from?

ST: I've asked myself that same question. I guess the answer is that I just sit down, play something that I like, and follow that path. One thing I really have is the feeling that something is good, and something is not. I know how to make those decisions but, the way things evolve and grow—that's a mystery to me.

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