Regarded by many to be the companion piece to Tangerine Dream’s previous “Phaedra” album, “Rubycon” does share more qualities than not for that to be the case. They both were the first and most durable of nearly one dozen albums released on Virgin Records; they contained a proliferation of mellotron, sequenced synthesizer and overall keyboard use while the liner notes were set in lower case Futura Light for streamlined, modern effect. (This short-lived feature ended on their following album, “Ricochet.”) Named likewise with single word titles, they were also both recorded in wintertime: “Phaedra” in December, 1973 and “Rubycon” January, 1975. The sessions for the album that preceded “Phaedra,” “Atem,” were also held during December, 1972 to January, 1973 so little wonder they all resonate with the atmosphere of chilly climes.

But for all these parallels, “Rubycon” was an entirely different construct than its predecessor: The album was one track per side instead of four in total; it feels considerably shorter (although the running time of “Rubycon” is short only by three minutes) and most of all: the identity of much of the instrumentation became less easily discernable due to the signal processors, tape echo and other effects they ran their equipment through. “Rubycon” was where their established keyboard arsenal of organ, e-piano and mellotron combined with their newer EMS, ARP and Moog synthesizers into a synthesis a step further into densely integrated convolutions. A Franke-Froese-Baumann gruppenkomposition, the two-part album title track “Rubycon” is a series of shifting overlays upon diffusive tones patched through manifold effects and manual sound manipulation plotted with percolating pulses and sequential rhythms into melting rivulets of sound running down mind-weaving corridors of spirographic patterning.

It all begins so quietly. Once nudging forward with gong taps that resonate gently against tremulous, reverberating keyboard clusters within a foreboding silence, “Rubycon Part One” breaks the clouds with a majestic gesture of daybreak setting sail under optimistic skies to new horizons. Bird calls echo and alternate while uplifting mellotron washes cascade evenly like uninterrupted, long distance waterfalls. Or turning like large schools of tiny fish whose iridescent scales flashing only at the one glittering angle where they all turn. With a giant echo, all of this falls away except for a mellotronic choir that holds until simmering into cymbal tones and lines as Synthi-A that ooze out in dribbling formations. This thin surface breaks with the advent of a synthesised sequencer line soon offset by a double-tracked (and/or possibly backward) mellotron theme that skates gracefully against the subtly shifting timbres of the background sequencer-driven pulsations. Soft e-piano droplets enter, forming and rippling in electronic pools as rhythms stream by at a variety of pulses, followed by Leslie-amplified guitar treatments. Further mellotron passages of cor anglais qualities continue to unfold until a single, backwards e-piano chord arcs up out of silence directly into a crescendo that cuts out abruptly in a cloud of reverb. Now agitated, the sequencer slowly modulates into percussive tones to massage the passage into a slowly melting glacial massif. Backwards piano drones drift by the constantly percolating sequencer that operate as latticework for the rush hour of electronics overlays that knead in waves of clusters against a variety of Leslie-amplified instruments of unidentifiable origin. The Moog sequencer modulates into a percussive timbre like an electric typewriter reporting at 48 words per minute on tumble dry low setting until more looming piano notes bang then resound in backward procession, followed by a wake of diffusive burblings. All drops down low for a solo mellotron theme to thread in and out as the sequencer lines start to weaken to 22 words per minute. Piano/organ keys through Leslie amplification and other dampening effects diffuse into the background to allow for a slow-motion assault on exposed strings of prepared piano. Backwards, treated zither strums against piano strings are struck to echo backwards in droning elongation as the now faltering and arrhythmic Moog sequencer lines decay altogether. With a final reverbed strum, the first side of “Rubycon” draws to a shuddering close.

“Rubycon Part Two” picks up from side one several nautical miles later with gentle resonation of gongs while VCS3 air raid siren wails sweeps over chilly nighttime waters like a Teutonic version of the introduction of Roxy Music’s “The Bob (Medley).” Clots of ghostly synthesizer trails and distant cries of alarm pass by in striations until Ligeti-like, black monolith choruses emerge; falling in pitch and rising in volume to drive the darting, sparse Moog filigrees and blanketing organ to drop off into stillness. Through a cloud of reverberation, a returning momentum gathers steadily with the quick and even paces of tightly woven sequencer lines stair-stepping up through the scrim of filtered, high-pitched Synthi-A. At one point, the cycle of notes shift as they dance in precision to interfacing with the streaks of backwards guitar. But as they slacken, they also approach the fore of the mix while strange, whirring tones emerge from within. Further trails of backwards guitar/organ/synthesizer streak by as if in opposition to the constant optimism of the peaking mellotron theme beaming in with angelic choir strength. This dense interplay continues even after the sequencer reassembles in speed and note order into tighter formation. After returning majestic washes of mellotron rise then fall away, the sequencer joins in decline while everything else adheres into echo and Leslie-amplified organ notes soon rotating slowly down into a swirling vortex. A final mellotron fanfare resounds slowed and muted below the surface while all else is soon sucked into the deep. Three lines of VCS3 sputter across the horizon as FX-gongs splash and crash like waves, their flowing undertow signaling that the far shore of the river Rubycon has finally been reached -- Only battered, washed ashore and shipwrecked in a damp, dark and barren landscape.

The epilogue unfolds under these tenuous conditions, bereft of sequencers and with twice as much silence. Minimal and spacious textures emerge and unravel as slowly as the group’s own previous zero gravity drift piece, “Fauni-Gena.” Minor Synthi-A chords emerge with an unresolved though beautiful mellotron passage as stars twinkle above this slow-moving mindscape. Gradually tweaked Synthi-A drapes the proceedings like mist as mellotron continues to grope in the darkness with unconstructed and sparse steps until these too, quietly drop off into silence.

The overlays, segues and constantly shifting soundscapes that create this odyssey make “Rubycon” the final robust statement from Tangerine Dream and as indicated by its title, marked a point of no return for the group. Their subsequent studio output, due to constant changes in both lineups and equipment, gradually displaced their former elements of spaced-out, serpentine mystery; alongside all the other timeless qualities that made this and all preceding Tangerine Dream’s albums so engaging, evocative and poetic in the first place.