Frank Ocean, Solange and Charli XCX are just a few high-profile artists Rostam Batmanglij spent studio time with while serving as a member of Vampire Weekend. After leaving the band in 2016 and flying solo with debut LP Half-Light, out Sept. 15, the 33-year-old revisits the works that define his career as a producer, songwriter and musician.

Vampire Weekend, “A-Punk” (2008)

My first job out of college was for a film composer named Craig Wedren, he’s also the lead singer of a band called Shudder to Think. One of the things that he gave me, so that I could help him, was this computer filled with sounds that I hadn't had before and one of them was chamberlain flutes. It was this very early sample collection where someone had gone in and recorded a flute player playing each note, and then assigned it to a keyboard and it was really early keyboard where when you pressed down on it, it started playing a tape so each note had its own tape that it would play.

I actually remember sophomore year of college, [Vampire Weekend lead singer] Ezra [Koenig] and me came out to L.A. for spring break with a couple other friends and one of the things we did was we went to see Jon Brion perform at Largo. I must’ve been like 20. I wanted to ask him about the Fiona Apple cover of “Across the Universe.” I think it’s one of the greatest recordings in history and I just wanted to pick Jon Brion’s brain about it and suddenly I was sitting next to him at this bar and I could do it. And one of the things I asked him about was the flute sound and he told me it was the chamberlain. So I had that in the back of my mind and I get a computer and all of a sudden I see chamberlain flute and so when we were putting the song together in the practice room, I was playing this really shitty Casio organ and we started working on “A-Punk.” I put all my organs and put them on the chamberlain flute.

I think that was going into the drum recording, so everything was kind of the scratch version: the scratch guitar, the scratch vocals, the scratch bass. And then I put the drums down then rebuilt everything after. So I didn't know if those chamberlain flutes would stay or if they were just a placeholder but I think they, in some ways, defined the song because I don’t think there’s very many recordings out there that put the chamberlain flutes so front and center because there’s really not very many other instruments. There’s just drums, bass, and chamberlain for the choruses of that song.

Discovery, “Swing Tree” (2009)

The Discovery records starting from me and [Ra Ra Riot’s] Wes [Miles] making music together and that started in the summer of 2005. And it just kinda evolved. At one point, we had a recording of “Can You Tell,” which is a song that Wes wrote and it evolved into a completely other version which I called “Can You Discover” and it set us down this path. There were these electronic ideas that sort of needed time adjusting and we always knew we were heading down the road to make an album. But it wasn't until the summer of 2009 that we finished it and put it out. So when I look back at the Discovery album, for me, I was learning how to construct beats, and unbeknownst to me, exploring a lot of ‘80s production techniques. I don’t think I really realized that until I played it for a friend and he was like, “Oh, this is really ‘80s,” and then it kinda clicked for me. I was kinda trying to do this futuristic version of the ‘80s. That’s where I was coming at it from. But yeah, those recordings were percolating before Vampire Weekend.

I remember that I had a Nokia phone and made the beat [for “Swing Tree”] from that, my ringtone. And everybody would ask me “What is that?” and I’d be like, “Oh just something that I made,” and they’d be like, “That’s pretty good.” It hung out as a beat. Like a lot of things on my record, it’s like I knew there was a good song there and it’s about taking the time to find the song there.

Vampire Weekend, “Diane Young” (2013)

It actually was in the second section of a song that was on my record, it’s called “Rudy” and originally when I sent the beat to Ezra it was called “Rudy Punk Part.” And I had imagined “Rudy” being this kind of like, almost “Bohemian Rhapsody” or “Paranoid Android” type, multi-part song. Like, very different sections. And it went from the very super Jamaican part that is “Rudy” to this straight-up punk part that became “Diane Young.” And I think we changed the key, but a lot of the original audio is still in there, weirdly. Like, you can kinda hear it in the background. So that’s for the heads.

“Rudy” started in 2009, so I knew that I wanted to finish it at one point, and that often happens, I think, when you do music and you have an open mind and things just kinda splinter in different directions. But it’s like a branch that breaks off and you carve the branch into a wooden spoon. It becomes something totally different, but it started in one place.

Carly Rae Jepsen, “Warm Blood” (2015)

It all happened here in my home studio. And Carly was an exception for me. In almost everyone I’ve worked with, I’ve had some sort of a friendship or I’ve gotten to know them a little outside of the studio, and it just felt like when we’ve got into the studio, it was sort of inevitable but not very planned. Carly was an exception in that I was a huge fan, and I reached out in the most traditional management type ways, which I’ve never really done. She appeared at my studio and she played me different things she was working on and I had no idea she had ever done things with Dev Hynes and I was like, “Wow.” I told her, “I think we should do something with strings.” And she was like, “I don’t want to do that, I want to get away from that." You can imagine any number of reasons.

She’s a true artist, so she has a vision for what she wants to do. So I started making a beat, and she started singing, and that was kind of the beginning of “Warm Blood,” so I sent her what we had from that day and she came back and I think it was over the course of seven months that she kept coming back to the studio and we kept making the song better and adding another section to the song. And by the time it was done, I felt like both of us were really proud of all the parts of the song and how they fit together.

Frank Ocean, “Ivy” (2016)

Frank and I were scheduled to do a session in the spring of 2011, and it fell through, and we never met in person, but we emailed back and forth a little bit. When Channel Orange came out [in 2012], I sent Frank an email and I was like “I’m listening to your record,” and that led to us hanging out in New York and staying in touch, and when I got to L.A. I went over to his place and he played me what he was working on and one of the things he played me was what became “Ivy.”

And as soon as he played it for me, I said, “I have a vision for what that can sound like,” and so then a few months later he brought the session here to my studio and I plugged in my electric guitar and I just sort of played the chords I heard in my head when he had played me the original version. I was kind of finding the chords as I was playing them, and those are the chords you hear on the record. I knew what I wanted the sound to be, I knew I wanted to use frame reverb and I knew I wanted to use this tape plug-in that modulates pitch. And it was very quickly that it came together.

Rostam, “Half-Light” (2017)

It is one of my favorite recordings I’ve ever done. When I wrote the song, I didn't know exactly what the word meant. But it was in finishing the album and choosing between different titles until I actually went to a dictionary and I found out that the word had a double meaning, that it meant both dawn and dusk. And at that point, I also had a Google doc where I mapped out all the lyrics of the whole record and I realized that there were so many lyrics referencing dawn, dusk, sunrise, sundown, and it wasn't something I was conscious of, so I like those connections but then I also liked broadly that the word “half-light” means at least two things and it could mean more and that felt important to me.

I like ambiguity sometimes, I think it’s important in songwriting. I think there’s a way to tell the whole story but also a way to use ambiguity as a tool as a writer.

Rostam, “Bike Dream” (2017)

The two boys in the song “Bike Dream” aren't literally two boys. I don’t know if everybody reads it as that. But I think it’s about feeling like you need to be two different people to make somebody that you’re with happy and it’s about wanting the person you’re with to be two different kinds of people. And I think that that’s something specific to those of us who don’t identify as straight but I also think it’s something that you can relate to if you do identify as straight. I don’t think it’s closed in that way. I think that that’s something that appealed to me as I was writing the song. Parts of which I wrote before I was out in press, so we’re talking about 2008, 2009.

I don’t know how to write songs that don’t share something of me. And I think with this album I can’t imagine any other person that it could come from so I guess it’s something I can’t be super conscious of.

A version of this article originally appeared in the September 23 issue of Billboard.