It's hard to avoid a feeling of déjà vu when reviewing Sepultura, as each new album from them seems to be based around an interesting concept crafted with a lot of care and attention, yet the songwriting itself can struggle to keep up. And so it's no surprise that Quadra, the fifteenth album from the Brazilians, is an interesting concept piece based around numerology and the four liberal arts (arithmetic, geometry, music, and astronomy) to the point where the songs are split between styles themselves, from classic thrash to groove and more experimental and progressive takes as explored on albums as diverse as Roots and Machine Messiah. This more than suggests that the band view their back catalogue as equal in quality and so will not indulge those that want a pure thrash album from them, and accordingly Quadra seems destined to please only those who enjoy latter-day Sepultura. Even those who do enjoy Derrick Green's vocals must admit that in his time with the band they have not released anything that matches up to past classics like Beneath the Remains or Arise, and although we are blessed with multiple groups that carry on various aspects of the Cavalera-fronted Sepultura, from the original band to Soulfly and Cavalera Conspiracy, few would deny wanting a truly razor-sharp killer thrash monster from Andreas Kisser and co.

This, to coin a phrase, ain't it, despite being a well-crafted metal album with plenty of aggressive heaviness and experimentation that will have wide appeal to fans of past releases. Isolation kicks the album off with some nicely heavy thrashing after a suitably epic orchestral intro, choir-backed choruses and plenty of impressively technical instrumental work from Kisser (still an underrated guitarist) and drummer Eloy Casagrande, who has more than filled Ig(g)or Cavalera's shoes. The two are an integral part of what keeps Sepultura's metal teeth sharp, easily recognisable as such from instrumental The Pentagram, one of the rare moments here that they're truly allowed to cut loose, and although Derrick Green's vocals tend towards hardcore barks rather than his very underappreciated bluesy singing (which does feature on late-album highlight Agony of Defeat at least) he's still a more than capable frontman (and definitely a better vocalist than Max Cavalera).

Highlights here will depend on taste, but there's much to take in, not least the stop-start groovy chugging of Means to an End, energetic with a nice percussive breakdown if a slight step down in thrash intensity from Isolation. It's a varied album that keeps a certain standard of aggressiveness, meaning that both Last Time's dense thrashing and Capital Enslavement's blunt groovy tribal metal are more than recognisably the work of the same band - and to give Sepultura credit where it's due, the latter never quite sinks to the nu-metal depths of Roots. There's never been a good reason for why the band's tribal influences couldn't be incorporated into their pure metal roots, and this is one of the better attempts to do so, staying aggressive and even throwing some lead guitar in there. The more interesting songs throughout are definitely the more experimental ones; for example Ali is more hardcore in style with lashings of dubstep-esque electronica here and there, while Guardians of Earth adds some acoustic strums in with the percussive progginess.

Sure, all seem to revert to the band's innate aggro-metal sooner or later, which can make the album hard to get into, and disappointingly there's nothing here as instantly infectious and well-written as Phantom Self or Iceberg Dances, two highlights from the band's previous album. Going back further and relistening to Kairos is downright depressing, the 2011 album the last release from Sepultura that seemed eager to at least attempt to reclaim their thrash heritage instead of consigning it to the shared past along with nu-metal and tribal experimentation. Yet Quadra has very few actual poor tracks, the slightly clumsy grooving mess that is Autem the nearest thing, and although it's a little too long at over fifty minutes it's overall the band's best showing since Kairos. Those with long memories will roll their eyes at being told a new Sepultura album is "their best since x" and although each new release manages to be interesting in its own right if not always surpassing previous efforts, Quadra at least shows a band still hungry and creative, even if it's a band that still won't give us what we really want from them.