MUSIC

90 Day Men emerged from Chicago’s underground at the turn of the millennium with a sharp, shape-shifting take on post-rock. Their Southern Records debut blended no wave tension with hypnotic repetition, carving out eight tracks that balance wiry rhythms and atmospheric drift.

This 25th anniversary edition expands the original release with a previously unheard album recorded at Steve Albini’s Electrical Audio. Engineered by Greg Norman and newly mastered by Heba Kadry, it sheds fresh light on the band’s restless creativity during their most exploratory phase.

A vital document of a scene in flux, (It (Is) It) Critical Band now stands taller than ever.

The songs on Touch, the first new Tortoise music in nine years, are dramas without words. They’re elaborately appointed and carefully mixed to enhance a familiar feeling — a distinctly cinematic uneasiness. Close your eyes and you might see cars swerving around unlit rural roads, or cityscapes at night with bells clanging in the distance, or some abandoned warehouse where spies chase each other between towering stacks of boxes.

The making of Touch is an entirely different kind of film — a heartwarming story of musicians adapting to life circumstances.

Tortoise operates as a collective; the five multi-instrumentalists make records by committee, seeking input on creative decisions large and small. All ideas are considered, and for most of the band’s influential three-decade run, the process has been straightforward: Each musician brings in songs or sketches, and as the group absorbs them, the players exchange ideas about the structure, instrumentation, different grooves or (more frequently, because they’re Tortoise) odd metric divisions that might stretch the initial conception of the song.

These discussions have always happened in real time, face to face. Until Touch. As guitarist and keyboardist Jeff Parker explains, over the last decade, the members of Tortoise scattered geographically, making the pre-production rehearsal sessions if not impossible, at least more complicated.

“It’s the first record we’ve done where everything wasn’t based in Chicago,” says Parker. “Two of us are in Chicago. Two of us are here in Los Angeles and John [McEntire] is in Portland, OR. We recorded in several different places. But the strange thing is, in a way it’s kind of the most cohesive session that we’ve done.”

McEntire, who plays drums, percussion, and keyboards and serves as mixing engineer, had little doubt that the actual recording would be fine. His apprehension was about those more open-ended development sessions leading up to the recording, which, he says, have been known to yield moments of peak Tortoise inspiration. “We don't work remotely, unfortunately. We kind of all have to be in the room together. For me the trial-and-error stage is very important. I didn’t want to lose that.”

The percussionist and multi-instrumentalist John Herndon explains one reason why: The path to a “final” version of a Tortoise tune is not a straight line. “It becomes writing and arranging and editing and orchestrating and sort of getting things into a sonic space that feels good, all at the same time.”

There was consensus about that; each of the musicians has a story about songs being transformed by the collaborative dynamic. Percussionist and keyboardist Dan Bitney recalls a session when they were working on one of his tunes. He wasn’t happy with it and promised to come up with a countermelody. “Right away somebody just asked “Does it need a melody? Like, why does this need a melody? And I’m like, “Yeah!” That’s the kind of thinking that can open your eyes.”

In the initial planning for the new record, the band arrived at what seemed like a reasonable geographic compromise: They’d set up shop at studios in three different areas — Los Angeles, Portland, and Chicago. They scheduled sessions with sometimes months in between, so that everyone could sit with the material and refine it further. The plan: To shift some of the wild idea-chasing of those development sessions from group work to individual work, building on Tortoise’s deep and iconoclastic lexicon of sounds — and on the trust between musicians that’s accrued over decades of music-making.

“It’s like, humans adapt,” Herndon says flatly. In order to keep making music as a group, he explains, everyone needed to be flexible then and remain so now. “If you’re used to doing something one way, and then it flips, well, you have to adapt to another way of working. I think that that's what we all were aspiring to do with this, endeavoring to kick in our adaptation skills.”

Still, it wasn’t smooth sailing. “I’m going to be honest, I think that we had some doubts” after the first set of sessions, McEntire recalls. Noting that four years elapsed from the beginning of Touch to its completion, he adds that “it took a long, long time for the music to coalesce. There was some ‘what are we doing?’ questioning going on along the way.”

Douglas McCombs, who plays guitar, bass, and the deep-voiced bass VI guitar that adds a noir luster to “Night Gang” and other Touch songs, believes that questioning would have happened regardless of the geographical challenges. “In the best circumstance, there’s a flow when we’re working on a tune. Everyone’s sparking ideas and inspired. It’s not work.” He adds, “In the worst moments, when we just absolutely don’t know what to do with something, it’s torturous.”

Herdon points to the early versions of “Vexations,” which became the new album’s opening track, as one such slow-torture situation. “We were confounded as to figuring out an arrangement, and things were just stuck,” he recalls. During one of the long lulls between the studio sessions, Herndon says, he got an idea for the tune. “I asked John if I could have the stems [the individual track files] for the song, and then I kind of did a reworking in the garage. Re-did the drums completely and made a breakdown section in the middle. I sent it and was like, ‘I don't know if this is anything, but here.’ And those guys seemed really excited about it.”

Herndon quickly adds that every Tortoise record has benefitted from similar experimentation. In fact, it’s the key thing, a defining characteristic: “Sometimes doing an edit will leave a space open for something else, and we’re all into that idea of, ‘What happens next?’ It’s this attitude of ‘Let’s make some music together and see what happens.’ We're all comfortable with the not knowing, with letting an idea go through many permutations.”

Along with that is the knowledge that this open-ended exploring can be time-consuming. And might possibly end in futility. McCombs says that though the band’s approach changed with Touch, the players still needed the mindset they’d used in those brainstorming rehearsals. “When I get frustrated or when we seem like we're stalling out a little bit, I just have to remember that patience is one of the things that makes this band work.”

Asked to recall a moment that required patience, McCombs doesn’t hesitate. “It seems to happen a lot with the drummers,” McCombs says. “Somebody will be like, ‘Hey John [McEntire] why don’t you play this?’ And he’ll be like, ‘I don’t wanna play it cause I hear Herndon here.’ It’s like McEntire hears Herdon and Herndon hears Bitney… That happens a lot, and then they’ll come to a consensus. Sometimes half the song will be one drummer and half the song will be another drummer. That’s kind of the way it works.”

**

It must be said: When things click into place, Tortoise is a rare force. Whether cranking out a foursquare rock backbeat or chopping time into polyrhythmic shards that defy counting (and logic), the band challenges accepted notions of what rock music can be, what moods it can evoke — that’s part of the reason the band is revered so widely, among musicians working in many genres.

Tortoise’s indescribable sonic arrays have grown more intense — and more influential — over time. Early works — the 1993 debut and the 1996 Millions Now Living Will Never Die, which opens with a twenty-one-minute suite — contrast the thick harmonic schemes of Krautrock with the similarly impenetrable densities of musique concrete, adding jarring spears of electric guitar as spice accents. The commercial breakthroughs that followed, TNT (1998) and Standards (2001) found Tortoise further expanding its toolkit: Rather than orient each piece around declarative single-line melodies, the musicians let the vast, lush, inviting scenes become a hypnotic wordless narrative, built from overlapping layers and interlocking rhythms.

Each step in the discography underscores a truth about Tortoise: The questions about arrangement and orchestration are foundational, defining the scope of the canvas and the density of the band’s exactingly precise soundscapes. There can, as McCombs notes, be multiple drummers on a track, and their beats can be supported by acoustic percussion or random electronic blippage. Likewise, on any given track, there can be multiple mallet parts, sometimes sustaining gorgeous washes of color, at other times pounding out intricate Steve Reich-style interlocked grids of harmony. There can be multiple guitars, each with its own earthshaking effects profile. (Parker laughs when he says “I’m kind of like the straight man with the guitar sounds.”) There can be multiple synthesizers — darting squiggles of lead lines crashing into asymmetrical arpeggios, or bliss-toned drones hovering in the upper-middle register like a cloud in a landscape painting.

And there can be noise, all kinds of it: While the working method of Touch meant Tortoise sacrificed some spontaneous sparks, it encouraged the musicians to explore the thickening textural possibilities of different flavors of noise (white, pink, etc). The band recently issued a set of remixes for the single “Oganesson.” The more austere, stripped-down interpretations offer telling insights about the deployment of noise as well as the track-by-track assembly process, the ways Tortoise uses open space, textural layers, and dissonances to create drama.

McEntire believes those little devices are essential to the sound. “Because we don't have a singer, we have to have a different vocabulary for creating interest. So we use all the little things, like dynamics, texture, orchestration.”

Given the intricacy of the music, McEntire explains, every little sound starts as a decision in the recording studio, and then, subsequently, becomes a logistical decision for live performance — after all, the many parts have to be executed by the five players.

The songs on Touch, the first new Tortoise music in nine years, are dramas without words. They’re elaborately appointed and carefully mixed to enhance a familiar feeling — a distinctly cinematic uneasiness. Close your eyes and you might see cars swerving around unlit rural roads, or cityscapes at night with bells clanging in the distance, or some abandoned warehouse where spies chase each other between towering stacks of boxes.

The making of Touch is an entirely different kind of film — a heartwarming story of musicians adapting to life circumstances.

Tortoise operates as a collective; the five multi-instrumentalists make records by committee, seeking input on creative decisions large and small. All ideas are considered, and for most of the band’s influential three-decade run, the process has been straightforward: Each musician brings in songs or sketches, and as the group absorbs them, the players exchange ideas about the structure, instrumentation, different grooves or (more frequently, because they’re Tortoise) odd metric divisions that might stretch the initial conception of the song.

These discussions have always happened in real time, face to face. Until Touch. As guitarist and keyboardist Jeff Parker explains, over the last decade, the members of Tortoise scattered geographically, making the pre-production rehearsal sessions if not impossible, at least more complicated.

“It’s the first record we’ve done where everything wasn’t based in Chicago,” says Parker. “Two of us are in Chicago. Two of us are here in Los Angeles and John [McEntire] is in Portland, OR. We recorded in several different places. But the strange thing is, in a way it’s kind of the most cohesive session that we’ve done.”

McEntire, who plays drums, percussion, and keyboards and serves as mixing engineer, had little doubt that the actual recording would be fine. His apprehension was about those more open-ended development sessions leading up to the recording, which, he says, have been known to yield moments of peak Tortoise inspiration. “We don't work remotely, unfortunately. We kind of all have to be in the room together. For me the trial-and-error stage is very important. I didn’t want to lose that.”

The percussionist and multi-instrumentalist John Herndon explains one reason why: The path to a “final” version of a Tortoise tune is not a straight line. “It becomes writing and arranging and editing and orchestrating and sort of getting things into a sonic space that feels good, all at the same time.”

There was consensus about that; each of the musicians has a story about songs being transformed by the collaborative dynamic. Percussionist and keyboardist Dan Bitney recalls a session when they were working on one of his tunes. He wasn’t happy with it and promised to come up with a countermelody. “Right away somebody just asked “Does it need a melody? Like, why does this need a melody? And I’m like, “Yeah!” That’s the kind of thinking that can open your eyes.”

In the initial planning for the new record, the band arrived at what seemed like a reasonable geographic compromise: They’d set up shop at studios in three different areas — Los Angeles, Portland, and Chicago. They scheduled sessions with sometimes months in between, so that everyone could sit with the material and refine it further. The plan: To shift some of the wild idea-chasing of those development sessions from group work to individual work, building on Tortoise’s deep and iconoclastic lexicon of sounds — and on the trust between musicians that’s accrued over decades of music-making.

“It’s like, humans adapt,” Herndon says flatly. In order to keep making music as a group, he explains, everyone needed to be flexible then and remain so now. “If you’re used to doing something one way, and then it flips, well, you have to adapt to another way of working. I think that that's what we all were aspiring to do with this, endeavoring to kick in our adaptation skills.”

Still, it wasn’t smooth sailing. “I’m going to be honest, I think that we had some doubts” after the first set of sessions, McEntire recalls. Noting that four years elapsed from the beginning of Touch to its completion, he adds that “it took a long, long time for the music to coalesce. There was some ‘what are we doing?’ questioning going on along the way.”

Douglas McCombs, who plays guitar, bass, and the deep-voiced bass VI guitar that adds a noir luster to “Night Gang” and other Touch songs, believes that questioning would have happened regardless of the geographical challenges. “In the best circumstance, there’s a flow when we’re working on a tune. Everyone’s sparking ideas and inspired. It’s not work.” He adds, “In the worst moments, when we just absolutely don’t know what to do with something, it’s torturous.”

Herdon points to the early versions of “Vexations,” which became the new album’s opening track, as one such slow-torture situation. “We were confounded as to figuring out an arrangement, and things were just stuck,” he recalls. During one of the long lulls between the studio sessions, Herndon says, he got an idea for the tune. “I asked John if I could have the stems [the individual track files] for the song, and then I kind of did a reworking in the garage. Re-did the drums completely and made a breakdown section in the middle. I sent it and was like, ‘I don't know if this is anything, but here.’ And those guys seemed really excited about it.”

Herndon quickly adds that every Tortoise record has benefitted from similar experimentation. In fact, it’s the key thing, a defining characteristic: “Sometimes doing an edit will leave a space open for something else, and we’re all into that idea of, ‘What happens next?’ It’s this attitude of ‘Let’s make some music together and see what happens.’ We're all comfortable with the not knowing, with letting an idea go through many permutations.”

Along with that is the knowledge that this open-ended exploring can be time-consuming. And might possibly end in futility. McCombs says that though the band’s approach changed with Touch, the players still needed the mindset they’d used in those brainstorming rehearsals. “When I get frustrated or when we seem like we're stalling out a little bit, I just have to remember that patience is one of the things that makes this band work.”

Asked to recall a moment that required patience, McCombs doesn’t hesitate. “It seems to happen a lot with the drummers,” McCombs says. “Somebody will be like, ‘Hey John [McEntire] why don’t you play this?’ And he’ll be like, ‘I don’t wanna play it cause I hear Herndon here.’ It’s like McEntire hears Herdon and Herndon hears Bitney… That happens a lot, and then they’ll come to a consensus. Sometimes half the song will be one drummer and half the song will be another drummer. That’s kind of the way it works.”

**

It must be said: When things click into place, Tortoise is a rare force. Whether cranking out a foursquare rock backbeat or chopping time into polyrhythmic shards that defy counting (and logic), the band challenges accepted notions of what rock music can be, what moods it can evoke — that’s part of the reason the band is revered so widely, among musicians working in many genres.

Tortoise’s indescribable sonic arrays have grown more intense — and more influential — over time. Early works — the 1993 debut and the 1996 Millions Now Living Will Never Die, which opens with a twenty-one-minute suite — contrast the thick harmonic schemes of Krautrock with the similarly impenetrable densities of musique concrete, adding jarring spears of electric guitar as spice accents. The commercial breakthroughs that followed, TNT (1998) and Standards (2001) found Tortoise further expanding its toolkit: Rather than orient each piece around declarative single-line melodies, the musicians let the vast, lush, inviting scenes become a hypnotic wordless narrative, built from overlapping layers and interlocking rhythms.

Each step in the discography underscores a truth about Tortoise: The questions about arrangement and orchestration are foundational, defining the scope of the canvas and the density of the band’s exactingly precise soundscapes. There can, as McCombs notes, be multiple drummers on a track, and their beats can be supported by acoustic percussion or random electronic blippage. Likewise, on any given track, there can be multiple mallet parts, sometimes sustaining gorgeous washes of color, at other times pounding out intricate Steve Reich-style interlocked grids of harmony. There can be multiple guitars, each with its own earthshaking effects profile. (Parker laughs when he says “I’m kind of like the straight man with the guitar sounds.”) There can be multiple synthesizers — darting squiggles of lead lines crashing into asymmetrical arpeggios, or bliss-toned drones hovering in the upper-middle register like a cloud in a landscape painting.

And there can be noise, all kinds of it: While the working method of Touch meant Tortoise sacrificed some spontaneous sparks, it encouraged the musicians to explore the thickening textural possibilities of different flavors of noise (white, pink, etc). The band recently issued a set of remixes for the single “Oganesson.” The more austere, stripped-down interpretations offer telling insights about the deployment of noise as well as the track-by-track assembly process, the ways Tortoise uses open space, textural layers, and dissonances to create drama.

McEntire believes those little devices are essential to the sound. “Because we don't have a singer, we have to have a different vocabulary for creating interest. So we use all the little things, like dynamics, texture, orchestration.”

Given the intricacy of the music, McEntire explains, every little sound starts as a decision in the recording studio, and then, subsequently, becomes a logistical decision for live performance — after all, the many parts have to be executed by the five players.

The Oganesson Remixes EP follows the March 2025 release of the “Oganesson” digital single, which was the first new music released by Tortoise since 2016. The EP includes the original version of “Oganesson” alongside five new remixes of the track created by collaborators and friends of the band, including poet and activist Saul Williams, prolific mastering engineer Heba Kadry, Black Keys drummer Patrick Carney, indie music icons Broken Social Scene, and International Anthem labelmate Makaya McCraven. The Oganesson Remixes EP comes ahead of a new album by Tortoise, which will be released this fall via International Anthem and Nonesuch Records.

Chicago Underground Duo is the long-running collaborative project of composer/trumpeter/electronicist Rob Mazurek (Exploding Star Orchestra, Isotope 217, New Future City Radio with Damon Locks) and composer/drummer/mbiraist Chad Taylor (jaimie branch’s Fly or Die, Marshall Allen’s Ghost Horizons, Luke Stewart’s Silt Trio). Hyperglyph is their first album in 11 years, and 8th in the absolute cabinet of wonders that is the Chicago Underground Duo.

The pair have played music together in a multitude of formations over nearly three decades, including their ongoing partnership in Mazurek’s large-format-skyward-expressionism vehicle Exploding Star Orchestra, in the expanded Chicago Underground Trio & Quartet (with guitarist Jeff Parker), and in a plethora of other assemblages. The early albums by the Duo have proven to be embryonic blueprints for the avant-jazz / electronic / indie rock hybridizations of the time, making them majorly important moments in the articulation of the “jazz” dimensionality of the then-burgeoning "post rock" sound. That sound, of course, was being transmitted far and wide due to the success of these groups as well as Mazurek’s Isotope 217 project with Jeff Parker, and the Chicago Underground’s frequent collaborators in Tortoise.

But the sounds being created by this extended family are and were far from static. Just as most of the still-working artists born of that Chicago era have evolved, reconfigured, and grown, Chicago Underground Duo has undergone a number of musical moltings, with the project always in the background of disparate individual aural investigations — always an option, always an outlet. As the project drops off and picks back up, the concurrent personal evolutions of Mazurek and Taylor make the Duo a true reflection of their own lives and friendship.

“Rob is my longest collaborator and also one of my best friends,” says Taylor, who first performed with Mazurek at a club in Chicago in 1988, aged 15.

“When it feels right we do it,” says Mazurek of the gaps in duo activity. “We have worked together and have been friends for a long time. This creates a kind of continuity not only in the music, but in our lives.”

Musically, there are certainly internalized nods here to AACM composers like Wadada Leo Smith, or albums like Don Cherry & Ed Blackwell’s “Mu” and El Corazon, but the songs of Hyperglyph exemplify Mazurek and Taylor’s individualities while also addressing another longtime influence on the Chicago Underground Duo sound — the Father, Son, and Holy Ghost of extreme studio editing in jazz-adjacent music, Miles Davis and Teo Macero’s Bitches Brew, In A Silent Way, and Get Up With It.

“Post production has always been a big part of our process,” says Taylor.

“Sometimes it just flows and we one-take a thing,” Mazurek elaborates. “Other things take time to ferment. We hit those hard in the post production.”

International Anthem engineer Dave Vettraino was indispensable as part of this process, recording and mixing the entire album at IARC HQ in Chicago. “We are very open and free in the studio,” says Mazurek. “Working with Dave is a joy because he is so intuitive and open with his approach as well. We can try anything with him. In this way it is more like a trio than a duo.”

Couple this trio’s take on the now classic cut-and-recut production techniques of Davis/Macero with Mazurek and Taylor’s longtime interest in deep electronic sounds (think Bernard Parmegiani, Morton Subotnick, Xenakis, Eliane Radigue, Plux Quba), transformative processing (think Autechre, King Tubby, Mouse On Mars, Carl Craig) and we can finally get close to understanding just where the duo lands in this lineage — this ongoing narrative each individual finds themselves in whether they see it or not. The Chicago Underground Duo, it seems, sees it.

While the musical language of Mazurek and Taylor can certainly be clocked in the slew of projects that they participate in together, the sound of a Chicago Underground Duo album is singular among them. Hyperglyph is no exception and could even be considered a distillation of that intuitive yet complex sound. A key can be found in the title of the album itself: highly complex geometric structures which can seem overly complex at first but, when thousands are arrayed in 3D space and with user training and adaptation, can significantly enhance perception and information assimilation and lead to new knowledge and insights.

The album opener “Click Song” kicks off with a blown-out horn chant from Mazurek, doubled by tuned bells and nestled into a muscular and symmetrical stereo-overdubbed polyrhythm from Taylor. Synthesized bass pulls our ears along cyclically, dropping in and out to almost severe dynamic effect while Mazurek and the subtle-yet-persistent bells elaborate upon the melody before ultimately departing from their repetitive psalm in favor of improvisation. It’s all held together by the steady, deep, chest-thump boom of Taylor’s kick drum pattern.

“There has always been a lot of African influence in the rhythms we play,” says Taylor. “With this record, specifically, we utilize rhythms from Nigeria, Mali, Zimbabwe, and Ghana.” Taken as a whole, spiritually, this introductory three-minute stomper lives somewhere between a Tuareg wedding and the most hypnotic moments of the click songs of Northern Africa.

Title track “Hyperglyph” follows, and begins with a chromatic moving harmony played by Mazurek on the RMI electric piano, an instrument famously utilized on Miles Davis’ groundbreaking Filles de Kilimanjaro. The vibe here, though, is one of unyielding, trancelike repetition. The trumpet introduces the time, with Taylor's chunky smacking rhythm hitting hard from the get go. Eventually, the tune undergoes a transformation, with the back and forth of melody and rhythm hitting a fever pitch. A pitch-shifted trumpet becomes a New Orleans march baritone. Dennis Bovell-style dub sounds enter (or, maybe, reveal themselves) at the start of the song’s final movement, followed by wordless incantations. Swelling and saturated, the track sounds as if it’s about to tear itself apart. Static pulsing merges and overtakes the recorded percussion to present a new rhythm of hissing electronics — the harnessed wailing of the unleashed ghost in the machine. A spiritual awakening from the bowels of the earth.

“Hemiunu”, a Chad Taylor composition, is a waltz based around a simple piano figure repeated throughout. A folk melody from anywhere, the kind that’s been in the air for as long as anyone can remember. One might imagine the melody played clawhammer on an Appalachian afternoon, bowed somberly on the Chinese erhu, or hummed nonchalantly on the factory line. From the jump, Taylor’s percussion threads itself into the sound of a well-worn upright piano as the high register is haunted in wide stereo by that roiling RMI electric piano in octaves, alternately dubby and harplike. Enter Mazurek with another folk-like melodic phrase. Pause. Again. Pause. Leaving room for the now densely waltzing bouquet to bloom before diving deep into laser-sharp Lee Morganesque territory with a wildly vibrating high trumpet cry, but with a tone Mazurek owns completely.

The deeper reference for Mazurek’s most untethered emotional playing is his late friend and mentor Bill Dixon, an extraction most apparent in the three-part "Egyptian Suite.” At the start of part one (“The Architect”) a cyclical pattern from Taylor becomes a bed for Mazurek’s repeating, descending, synthetic-Egyptian scaled theme. This call to action dissolves into the second movement, “Triangulation of Light,” where Taylor’s bowed cymbals set the stage for an exploration of microtonal color with and against the occasional joining and un-joining of tones that stretch the frequencies to their limits from Mazurek's open and half muted trumpet. Like a tornado siren in the distance, breaking through the membrane of storm clouds on the horizon, in search of another siren.

The third and final movement, “Architectonics of Time,” announces itself with free rolling swaths of percussion from Taylor à la Robert Frank Pozar’s mind-bending percussion on The Bill Dixon Orchestra’s classic Intents and Purposes. Here, though, the lineup is limited to two, with no overdubs or post-production. Taylor's singular style and Mazurek's tonal painting coalesce into a maelstrom of intervallic tone and beat before the final repeat of the lead melody from the suite’s first movement. It truly feels like reaching the summit. It’s pure and free duo interaction, the symbiosis of 30 years.

“Succulent Amber,” the final track on Hyperglyph, could fit just as easily on side two of Autobahn. After a brief modular synth-induced pan-harmonic melody shift, a steady kalimba is joined by the gentle intermittent raindrop-melodicism of the RMI electric piano in this understated final duo performance, unadorned by further studio arrangement. It’s a full-on comedown moment after the intensity of “Egyptian Suite,” though rather than winding down or petering out, here the Chicago Underground Duo still manage to point toward some kind of incoming mystery with four sudden-yet-patient ascending chords on the low-register of the RMI electric piano just before the curtains close. The piano notes end on a leading tone, leaving the resolution to the listener.

Once we’ve climbed the mountain, they remind us, we have to deal with what’s on the other side.

Chicago Underground Duo is the long-running collaborative project of composer/trumpeter/electronicist Rob Mazurek (Exploding Star Orchestra, Isotope 217, New Future City Radio with Damon Locks) and composer/drummer/mbiraist Chad Taylor (jaimie branch’s Fly or Die, Marshall Allen’s Ghost Horizons, Luke Stewart’s Silt Trio). Hyperglyph is their first album in 11 years, and 8th in the absolute cabinet of wonders that is the Chicago Underground Duo.

The pair have played music together in a multitude of formations over nearly three decades, including their ongoing partnership in Mazurek’s large-format-skyward-expressionism vehicle Exploding Star Orchestra, in the expanded Chicago Underground Trio & Quartet (with guitarist Jeff Parker), and in a plethora of other assemblages. The early albums by the Duo have proven to be embryonic blueprints for the avant-jazz / electronic / indie rock hybridizations of the time, making them majorly important moments in the articulation of the “jazz” dimensionality of the then-burgeoning "post rock" sound. That sound, of course, was being transmitted far and wide due to the success of these groups as well as Mazurek’s Isotope 217 project with Jeff Parker, and the Chicago Underground’s frequent collaborators in Tortoise.

But the sounds being created by this extended family are and were far from static. Just as most of the still-working artists born of that Chicago era have evolved, reconfigured, and grown, Chicago Underground Duo has undergone a number of musical moltings, with the project always in the background of disparate individual aural investigations — always an option, always an outlet. As the project drops off and picks back up, the concurrent personal evolutions of Mazurek and Taylor make the Duo a true reflection of their own lives and friendship.

“Rob is my longest collaborator and also one of my best friends,” says Taylor, who first performed with Mazurek at a club in Chicago in 1988, aged 15.

“When it feels right we do it,” says Mazurek of the gaps in duo activity. “We have worked together and have been friends for a long time. This creates a kind of continuity not only in the music, but in our lives.”

Musically, there are certainly internalized nods here to AACM composers like Wadada Leo Smith, or albums like Don Cherry & Ed Blackwell’s “Mu” and El Corazon, but the songs of Hyperglyph exemplify Mazurek and Taylor’s individualities while also addressing another longtime influence on the Chicago Underground Duo sound — the Father, Son, and Holy Ghost of extreme studio editing in jazz-adjacent music, Miles Davis and Teo Macero’s Bitches Brew, In A Silent Way, and Get Up With It.

“Post production has always been a big part of our process,” says Taylor.

“Sometimes it just flows and we one-take a thing,” Mazurek elaborates. “Other things take time to ferment. We hit those hard in the post production.”

International Anthem engineer Dave Vettraino was indispensable as part of this process, recording and mixing the entire album at IARC HQ in Chicago. “We are very open and free in the studio,” says Mazurek. “Working with Dave is a joy because he is so intuitive and open with his approach as well. We can try anything with him. In this way it is more like a trio than a duo.”

Couple this trio’s take on the now classic cut-and-recut production techniques of Davis/Macero with Mazurek and Taylor’s longtime interest in deep electronic sounds (think Bernard Parmegiani, Morton Subotnick, Xenakis, Eliane Radigue, Plux Quba), transformative processing (think Autechre, King Tubby, Mouse On Mars, Carl Craig) and we can finally get close to understanding just where the duo lands in this lineage — this ongoing narrative each individual finds themselves in whether they see it or not. The Chicago Underground Duo, it seems, sees it.

While the musical language of Mazurek and Taylor can certainly be clocked in the slew of projects that they participate in together, the sound of a Chicago Underground Duo album is singular among them. Hyperglyph is no exception and could even be considered a distillation of that intuitive yet complex sound. A key can be found in the title of the album itself: highly complex geometric structures which can seem overly complex at first but, when thousands are arrayed in 3D space and with user training and adaptation, can significantly enhance perception and information assimilation and lead to new knowledge and insights.

The album opener “Click Song” kicks off with a blown-out horn chant from Mazurek, doubled by tuned bells and nestled into a muscular and symmetrical stereo-overdubbed polyrhythm from Taylor. Synthesized bass pulls our ears along cyclically, dropping in and out to almost severe dynamic effect while Mazurek and the subtle-yet-persistent bells elaborate upon the melody before ultimately departing from their repetitive psalm in favor of improvisation. It’s all held together by the steady, deep, chest-thump boom of Taylor’s kick drum pattern.

“There has always been a lot of African influence in the rhythms we play,” says Taylor. “With this record, specifically, we utilize rhythms from Nigeria, Mali, Zimbabwe, and Ghana.” Taken as a whole, spiritually, this introductory three-minute stomper lives somewhere between a Tuareg wedding and the most hypnotic moments of the click songs of Northern Africa.

Title track “Hyperglyph” follows, and begins with a chromatic moving harmony played by Mazurek on the RMI electric piano, an instrument famously utilized on Miles Davis’ groundbreaking Filles de Kilimanjaro. The vibe here, though, is one of unyielding, trancelike repetition. The trumpet introduces the time, with Taylor's chunky smacking rhythm hitting hard from the get go. Eventually, the tune undergoes a transformation, with the back and forth of melody and rhythm hitting a fever pitch. A pitch-shifted trumpet becomes a New Orleans march baritone. Dennis Bovell-style dub sounds enter (or, maybe, reveal themselves) at the start of the song’s final movement, followed by wordless incantations. Swelling and saturated, the track sounds as if it’s about to tear itself apart. Static pulsing merges and overtakes the recorded percussion to present a new rhythm of hissing electronics — the harnessed wailing of the unleashed ghost in the machine. A spiritual awakening from the bowels of the earth.

“Hemiunu”, a Chad Taylor composition, is a waltz based around a simple piano figure repeated throughout. A folk melody from anywhere, the kind that’s been in the air for as long as anyone can remember. One might imagine the melody played clawhammer on an Appalachian afternoon, bowed somberly on the Chinese erhu, or hummed nonchalantly on the factory line. From the jump, Taylor’s percussion threads itself into the sound of a well-worn upright piano as the high register is haunted in wide stereo by that roiling RMI electric piano in octaves, alternately dubby and harplike. Enter Mazurek with another folk-like melodic phrase. Pause. Again. Pause. Leaving room for the now densely waltzing bouquet to bloom before diving deep into laser-sharp Lee Morganesque territory with a wildly vibrating high trumpet cry, but with a tone Mazurek owns completely.

The deeper reference for Mazurek’s most untethered emotional playing is his late friend and mentor Bill Dixon, an extraction most apparent in the three-part "Egyptian Suite.” At the start of part one (“The Architect”) a cyclical pattern from Taylor becomes a bed for Mazurek’s repeating, descending, synthetic-Egyptian scaled theme. This call to action dissolves into the second movement, “Triangulation of Light,” where Taylor’s bowed cymbals set the stage for an exploration of microtonal color with and against the occasional joining and un-joining of tones that stretch the frequencies to their limits from Mazurek's open and half muted trumpet. Like a tornado siren in the distance, breaking through the membrane of storm clouds on the horizon, in search of another siren.

The third and final movement, “Architectonics of Time,” announces itself with free rolling swaths of percussion from Taylor à la Robert Frank Pozar’s mind-bending percussion on The Bill Dixon Orchestra’s classic Intents and Purposes. Here, though, the lineup is limited to two, with no overdubs or post-production. Taylor's singular style and Mazurek's tonal painting coalesce into a maelstrom of intervallic tone and beat before the final repeat of the lead melody from the suite’s first movement. It truly feels like reaching the summit. It’s pure and free duo interaction, the symbiosis of 30 years.

“Succulent Amber,” the final track on Hyperglyph, could fit just as easily on side two of Autobahn. After a brief modular synth-induced pan-harmonic melody shift, a steady kalimba is joined by the gentle intermittent raindrop-melodicism of the RMI electric piano in this understated final duo performance, unadorned by further studio arrangement. It’s a full-on comedown moment after the intensity of “Egyptian Suite,” though rather than winding down or petering out, here the Chicago Underground Duo still manage to point toward some kind of incoming mystery with four sudden-yet-patient ascending chords on the low-register of the RMI electric piano just before the curtains close. The piano notes end on a leading tone, leaving the resolution to the listener.

Once we’ve climbed the mountain, they remind us, we have to deal with what’s on the other side.

"This cassette is a promo mix that we originally sold in high school to promote the parties my friends and I did back then (The Witch Is Back); M.O.A. Productions, Frantik Party Productions, some of my earliest House crews.

We (Marky P, DJ Juice, DPC, James) did underground house parties in basements and around while in high school. The mix is a fusion of Chicago house, and also the European minimal techno that was coming into Chicago back then. A timestamp on our histories, early roots and what we love."

— Mark Grusane