A concept album exploring themes of broadcast communications, Radio-Activity marked Kraftwerk's return to more obtuse territory, extensively utilizing static, oscillators, and even Cage-like moments of silence to approximate the sense of radio transmission; a pivotal record in the group's continuing development, the title track – the first they ever recorded in English – is their most fully realized electro-pop effort to date, while "The Voice of Energy" precipitates the robot voice so crucial to their subsequent work.

Although Kraftwerk's first three albums were groundbreaking in their own right, Autobahn is where the group's hypnotic electronic pulse genuinely came into its own. The main difference between Autobahn and its predecessors is how it develops an insistent, propulsive pulse that makes the repeated rhythms and riffs of the shimmering electronic keyboards and trance-like guitars all the more hypnotizing. The 22-minute title track, in a severely edited form, became an international hit single and remains the peak of the band's achievements – it encapsulates the band and why they are important within one track – but the rest of the album provides soundscapes equally as intriguing. Within Autobahn, the roots of electro-funk, ambient, and synth pop are all evident – it's a pioneering album, even if its electronic trances might not capture the attention of all listeners.

The Man-Machine is closer to the sound and style that would define early new wave electro-pop – less minimalistic in its arrangements and more complex and danceable in its underlying rhythms. Like its predecessor, Trans-Europe Express, there is the feel of a divided concept album, with some songs devoted to science fiction-esque links between humans and technology, often with electronically processed vocals ("The Robots," "Spacelab," and the title track); others take the glamour of urbanization as their subject ("Neon Lights" and "Metropolis"). Plus, there's "The Model," a character sketch that falls under the latter category but takes a more cynical view of the title character's glamorous lifestyle. More pop-oriented than any of their previous work, the sound of The Man-Machine – in particular among Kraftwerk's oeuvre – had a tremendous impact on the cold, robotic synth pop of artists like Gary Numan, as well as Britain's later new romantic movement.

Continuing to work with Conny Plank, who once again provides a compelling job as producer and engineer, Kraftwerk went right ahead and named their new album after their two remaining members – an understandable enough move. Like the first two albums, Ralf and Florian still has not seen official re-release, for all that one can practically taste Kraftwerk's leap into the beyond on it. Given that this was the last album before the most famous lineup was formed and Autobahn was released, it's appropriate to listen to Ralf and Florian as a harbinger for the future, though perhaps all too easy. Take it on its own terms – a further investigation of electronic possibilities in a more open-ended, less constantly structured fashion than would be the case later – and Ralf and Florian becomes most enjoyable.

The line-up on this newly released bootleg is said to consist of Florian Schneider, Michael Rother and Klaus Dinger, which tells us that this was probably recorded in that short period of time in 1971, estimated to 6 months, when Ralf Hütter had left the band. Supposedly, the recording was made at the Gondel Kino in Bremen, Germany on June 25, 1971. And it's an interesting recording.

Although Autobahn was a left-field masterpiece, Trans-Europe Express is often cited as perhaps the archetypal (and most accessible) Kraftwerk album. Melodic themes are repeated often and occasionally interwoven over deliberate, chugging beats, sometimes with manipulated vocals; the effect is mechanical yet hypnotic.

Like its predecessor (similarly designed right down to the traffic cone cover, though green instead of red), Kraftwerk 2 has never been properly re-released, giving it the same lost-classic aura as the first album, or at least lost, period. Thankfully, bootleg reissues in 1993 restored it to wider public listening; even more so than Kraftwerk 1, its lack of official reappearance is a mystery, in that the band is clearly well on its way to the later Kraftwerk sound of fame. Stripped down to the Hütter/Schneider duo for this release, and again working with Conrad Plank as coproducer and engineer (this album alone demonstrates his ability to create performances combining technological precision and warmth), Kraftwerk here start exploring the possibilities of keyboards and electronic percussion in detail. Given that the band's drummers were gone, such a shift was already in the wind, but it's the enthusiastic grappling with drum machines and their possibilities that makes Kraftwerk 2 noteworthy.

The byproduct of a much anticipated, long-delayed, and ultimately scrapped album to have been called Technopop (and to have contained Kraftwerk's great dance single "Tour de France"), 1986's Electric Cafe suffers only slightly from lacking the thematic focus of previous Kraftwerk albums. Ironically, the '80s techno-pop wave had passed by band founders Florian Schneider and Ralf Hutter at this point, but their sly wit ("Boing Boom Tschak," "Telephone," "Sex Object") and melodic inventiveness still stand the test of time. Its segues virtually seamless, Electric Cafe plays like one mega-dance-mix, but with the tasteful restraint that has long been a Kraftwerk hallmark. This is club music for thinking men and women.

What might have been simply seen as an agreeable enough debut album has since become something of a notorious legend because Kraftwerk, or more accurately the core Hütter/Schneider duo at the heart of the band, simply refuses to acknowledge its existence any more. What's clearly missing from Kraftwerk is the predominance of clipped keyboard melodies that later versions of the band would make their own. Instead, Kraftwerk is an exploratory art rock album with psych roots first and foremost, with Conny Plank's brilliant co-production and engineering skills as important as the band performances. Still, Hütter and Schneider play organ and "electric percussion" – Hütter's work on the former can especially be appreciated with the extended opening drone moan of the all-over-the-place "Stratovarius" combined with Schneider's eerie violin work. But it's a different kind of combination and exploration, with the key pop sugar (and vocal work) of later years absent in favor of sudden jump cuts of musique concrète noise and circular jamming as prone to sprawl as it is to tight focus.

This is the japanese version of Kraftwerk - Concert Classics. Various versions seem to exist. With transparent and with black jewelcases. On the back and front of the case a blue sticker is attached. Therefore transparent jewelcase have another cover with the Autobahn logo in blue on black. When the CD was released in 1998 a Japanese press release is said to state that the concert was recorded in Dallas Broncos Bowl on 1/5/1975. However latest investigations to a series of recordings from Denver clearly indicate this recording coming from a 20/05/1975 gig in Denver.