Saxophonist Chris Potter‘s new album, Imaginary Cities, came out on ECM last week. (Buy it from Amazon.) It’s his second release for the label, following 2013’s The Sirens, and like that one, it’s a concept album of sorts. That’s where the similarities end, though. The Sirens was an acoustic quintet disc, comprised of discrete pieces all based on themes from Homer‘s The Odyssey. This time, he’s expanded his long-running group the Underground (guitarist Adam Rogers, keyboardist Craig Taborn and drummer Nate Smith), turning it into the Underground Orchestra with the addition of vibraphonist Steve Nelson, two bassists (Scott Colley on upright and Fima Ephron on electric), and a string quartet composed of Mark Feldman and Joyce Hammann on violins, Lois Martin on viola and David Eggar on cello.

Nearly half of the album’s running time is taken up by the title suite, which runs through four movements—”Compassion,” “Dualities,” “Disintegration” and “Rebuilding”—and at least as many moods, from string-led balladry to African-esque groove to surprisingly free sections, and well beyond. The three tracks that follow the suite, “Firefly,” “Shadow Self,” and “Sky,” may be less epic, but the players never slack off or make the easy choice. While there’s plenty of accessible melody on Imaginary Cities, and lots of the hard-driving rhythm the Underground is known for, this is an album that takes both the listener and the players on an adventurous journey, one that proves extraordinarily rewarding.

—Phil Freeman

Watch a short video about the making of the album:

Potter answered a few questions about Imaginary Cities via email.

Did this project arise as a way to break out of the constraints of what the Underground quartet could do, or did you realize you needed them to provide a foundation for the more exploratory material here, or was it somewhere in between?
This project arose out of a couple of concerts I was asked to do at Lincoln Center. I decided to use the opportunity to do something different than I had done previously and write for a slightly unusual large ensemble, but I also wanted to use musicians that I know well and have a history with. All the musicians in Underground are more than capable of going in many different directions, so that wasn’t a problem, the issue was for me to decide what kind of statement I really wanted to make. My desire was to challenge myself with a writing and performing situation that stretched my abilities both conceptually and technically, and I wanted to have good musical friends around me to help it work.

The combination of electric and upright bass is probably most recognized from Miles Davis’s Bitches Brew. What do you think Fima Ephron and Scott Colley bring to the music, separately and together?
We performed a week once as a quintet at the Village Vanguard with Fima, Scott, Nate and Adam. I loved how the two bass players played together and interacted, and the interesting grooves that arose from this configuration. There is a lot of variation possible—they can play together, separately, Scott can play with a bow, one of them can have more of a high solo role while the other one holds the bass function down, etc. They brought a mass to the bottom of the rhythm section that I balanced with the higher vibraphone and piano registers. Also they are just two of my favorite musicians to work with on any instrument, because of their acute ability to listen and provide support in any situation. A big reference point for me was John Coltrane’s Africa/Brass sessions (though in that case they were both acoustic basses).

Half the running time of the new album is taken up by the title piece. Your previous album, The Sirens, was a collection of separate pieces, but it had thematic continuity. Has signing with ECM freed you up to work on a broader canvas than before?
I would say that starting from an extramusical theme is something I’ve discovered in the past few years can help free my musical imagination in a way; it points me towards composing more from a “mood” angle than a technical one. While I’ve been very happy working with ECM, I conceived and wrote the music for both albums before arranging the record dates, so I don’t really think that’s a factor, however I’m very grateful that Manfred Eicher at ECM agreed to take on and fund a project of this size, and he has a very keen ear in the studio. I found his input invaluable.

You don’t just use the strings behind the band, all the time; the musicians are constantly splitting up into small subgroups. Was this something that was determined during the writing process, or in the studio, in the moment? Put another way, how pre-arranged was the music?
It all had to be pretty carefully planned. We had two days to rehearse, played two concerts, then recorded about a week later, so I had to make sure everything worked on the first go-round, there was no time to to revise. The written sections are all fairly tightly arranged, as are the string background sections, and I made an effort to try and use a lot of the different textural possibilities that the instrumentation offered in my writing approach. For the improvised sections, we figured out which musicians would play behind which soloist as we went along (sometimes it would be electric bass with guitar support, sometimes upright bass with piano or vibes support, and various other permutations), and I left those sections as open as possible to allow for as much interplay and open communication as possible.

You’re performing the music from this album on the East and West Coasts—how much of this material do you foresee entering the regular Underground book?
We’ve played small group versions of all this music, that’s not a problem. We leave out certain sections and of course it’s texturally very different, but what we lose in numbers hopefully we gain in flexibility!

Buy Imaginary Cities from Amazon