Ethereal, atmospheric and boldly reinvented. Altered State is Tesseract’s 2013 album: a spacious, sax-tinged evolution of British prog metal.

The short version

The 2013 second studio album by British prog-metal pioneers Tesseract, and one of the most acclaimed records of the modern djent movement. A bold, atmospheric reinvention, it abandons the growls of their debut in favour of soaring, entirely clean vocals from new singer Ashe O’Hara, wrapping the band’s signature polyrhythmic grooves in shimmering ambience and even jazz saxophone. Structured as four flowing conceptual suites, it trades brute heaviness for mood, melody and emotional depth. Ethereal, intricate and beautifully produced, it stands as a high point of atmospheric progressive metal.

A bold new direction

Tesseract emerged from Milton Keynes as one of the leading lights of djent, the groove-heavy, polyrhythmic strain of modern progressive metal. For Altered State, the band paired their core line-up — guitarists Acle Kahney and James Monteith, bassist Amos Williams and drummer Jay Postones — with new vocalist Ashe O’Hara, whose soft, soaring, entirely clean voice defined the album’s sound. It remains the band’s only full-length with O’Hara, and a distinctive one at that. Guest saxophonist Chris Barretto and guitarist Paul Waggoner of Between the Buried and Me added further colour, helping Tesseract push their music into richer, more atmospheric territory.

The sound

Altered State is ethereal, djent-driven prog metal, atmospheric and intricate. It builds on Tesseract’s trademark blend of syncopated, polyrhythmic grooves and spacious ambience, but leans further than ever into mood, melody and emotion. O’Hara’s clean, angelic vocals soar over churning, low-tuned guitars and Jay Postones’ intricate drumming, while shimmering, ambient textures give the album a dreamlike, otherworldly feel. The addition of smoky jazz saxophone on a couple of tracks is a striking, unexpected touch, deepening the album’s reflective, cinematic atmosphere. Heavy yet graceful, complex yet cohesive, it is a masterclass in balancing crushing groove with delicate beauty.

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The songs

‘Nocturne’ was the album’s first single, a soaring, passionate showcase featuring a guest guitar solo from Paul Waggoner. ‘Exiled’ is a sprawling, reflective centrepiece that pairs delicate, acoustic-tinged passages with breathtaking vocals. And ‘Singularity’ is an eight-minute epic that shows off the band’s dynamic range, from ambient calm to explosive, groove-driven power.

Reception and legacy

Altered State was met with widespread acclaim, praised as a bold, mature evolution of Tesseract’s sound and one of the finest albums of the djent era. Critics singled out O’Hara’s stunning vocals, the album’s rich atmosphere and its adventurous touches — the saxophone above all — while some longtime fans missed the heavier edge of the debut. Its blend of complexity, groove and beauty proved hugely influential on the wider progressive-metal scene. Though O’Hara would move on soon after, Altered State remains a beloved, singular entry in the band’s catalogue — and a landmark of atmospheric modern metal.

The verdict

Altered State is Tesseract at their most atmospheric and adventurous: ethereal, djent-driven prog metal built on polyrhythmic grooves, shimmering ambience and O’Hara’s soaring clean vocals. Come for the passionate ‘Nocturne’ and the sprawling ‘Exiled.’ Intricate, beautiful and boldly reinvented, it is essential listening for anyone who likes their progressive metal spacious, emotional and endlessly detailed — and one of the defining albums of the modern djent movement.

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