Earlier this year, Oulu (a city in Northern Finland) witnessed an unusual event: a day dedicated to listening to the entire recorded output of Circle.

With most bands that have been in circulation since the mid ’90s, this would’ve resulted in an afternoon of music at most. With this celebrated cult outfit from Pori (a small town on the Western Coast of Finland) however, the result was nothing short of an extreme marathon event: with a steadily growing, hugely diverse discography of 30-odd albums (plus live recordings, EPs, numerous side projects and collaborations), the production rate of these uncrowned kings of the Finnish musical underground is awe-inspiring, if not downright terrifying.

None of which would add up to much beyond a footnote as “the most prolific band” in the Guinness Book of Records were all those albums not up to scratch. But here’s the thing: although there have inevitably been some blips in the quality control department, including occasions when the band’s uniquely deranged vision hasn’t necessarily made all that much sense for the average listeners, in Circle’s case the Stakhanovite efforts in the studio haven’t affected the strike rate. And so it is with this latest twosome of releases.

Manner is the follow-up (nearly: there’s also Infektio, last year’s addition to Circle’s sideline in improvised noodle-soup) to 2010’s outstanding avant-arena rock blast Rautatie, which was probably the most satisfying and accessible blend so far of the band’s unique blend of old-school Tarzan-metal wailing, autobahn-gobbling krautrock grooves, gonzo humour, gargantuan riffs and frequent flights to the outer reaches of the cosmos. In true Circle fashion, having one new album out isn’t quite enough: as such, Manner is joined by Serpent, showcasing Circle’s expanded three-guitar line-up in action on stage in Bristol last year.

Manner throbs with more energy and forward-surging drive than we have any right to expect from a band with some 15 years on the meter and around 30 albums to their name. As ever with peak-form Circle, it sounds a lot like – but also utterly distinct from – its predecessors. Apart from the superlative blend of 24-carat kraut-boogie chug and vocalist/keyboardist Mika Rättö’s mock-operatic, stainless steel wail that is ‘Mustaa Kultaa’ (‘Black Gold’ to the non-Finnish folk out there) and the vintage hard rock tribute ‘Blue King’, the triple-guitar assaults that powered Rautatie hover around the edges, adding arresting detail as opposed to hogging the spotlight, whilst some thoroughly ace levitational grooves, testament to Circle’s all-enveloping belief in the restorative powers of hypnotic repetition, occupy centre stage. As evidenced by the brilliantly batshit creepy crawl of future Circle classic ‘Lintu Joe’, Manner is for the main part a steadily paced, slicked-up beast, hooking the listener gradually (but irreparably), taking the occasional break from its minimalist mission to gallop towards high voltage Armageddon astride outbreaks of explosive avant-boogie.

As anyone who has witnessed the band on stage can testify, Circle are a peerlessly powerful live act. Which explains their habit of putting out live albums, Serpent being the eighth in an ongoing series. As ever, not actually being there does diminish the experience somewhat: without the incredibly entertaining visuals – past shows have featured leather-and-metal clad Rättö and bassist/founder Jussi Lehtisalo staging an arm-wrestling match on stage without the band missing a beat – segments such as the extended instrumental section on ‘Rautatie’ don’t really translate that well. But with overcharged gallops through Rautatie highlight ‘Vaellus’ and strong previews of Manner‘s trance-inducing contents to offer, Serpent‘s essential listening for Circle-heads. Manner, meanwhile, is an ideal gateway to the band’s weird and wonderful world, and is: