Perhaps surprisingly for a genre built on instrumental technique, prog gave a platform to some of rock’s most unique voices. Peter Gabriel‘s tenure with Genesis was marked by an intense theatricality, as well as nerdy wordplay; he was always playing a character, even when that character was “rock singer.” Yes frontman Jon Anderson‘s elfin upper register and shockingly powerful yells were the perfect analogue for his bandmates’ music, which leapt from woodsy placidity to hard-charging, polyphonic outbursts and back. Rush bassist Geddy Lee is similarly gifted in the high-note department; his nasal screech launches itself above the band’s power-trio mathematics, zipping and squawking like an insane parrot repeating poems learned from drummer Neal Peart.

Van Der Graaf Generator leader Peter Hammill sounds like almost no one else. His vocal range is relatively low, compared to Anderson, Gabriel or Lee (though he’ll occasionally adopt a weird, androgynous falsetto that recalls Vincent Crane of Atomic Rooster), and much less controlled. Indeed, he inhabits his lyrics so deeply that they come across like a madman’s desperate attempts to communicate his hallucinations to an impassive world. His voice cracks at the end of lines, or syllables are extended to the point that they dissolve into quaver; he chews on every word with almost breathless passion, his voice coiling unpredictably around the rhythm like a snake trying to avoid capture.

His bandmates during the band’s classic years—keyboardist Hugh Banton, saxophonist David Jackson, and drummer Guy Evans—were as inspired as he was. On their first three albums, The Least We Can Do Is Wave to Each Other and H to He, Who Am the Only One, both released in 1970, and Pawn Hearts, from 1971, Banton’s electric organ and Evans’ pummeling, aggressive drumming created songs filled with darkness and terror, without employing the clichés of hard rock or psychedelia. Jackson’s saxophones (he sometimes played two at once, in the manner of Rahsaan Roland Kirk) mostly stayed in the background, serving more as a Greek chorus than a lead instrument, though when he did take solos, he was capable of a fierce, skronking fury—on “White Hammer,” from The Least…, he sounds like Steve Mackay battling Peter Brötzmann.

Overworked from a typically heavy early ’70s touring schedule, and not nearly as commercially successful as their peers (despite a co-sign from King Crimson‘s Robert Fripp, who played on H to He… and Pawn Hearts), they split up in 1972. Three years later, though, they reunited, and made three more albums, 1975’s Godbluff and 1976’s Still Life and World Record, after which Banton and Jackson left again. Hammill brought in Nic Potter, who’d played bass on The Least… and H to He…, and violinist Graham Smith, and released The Quiet Zone/The Pleasure Dome, before embarking on a full-time solo career.

In 2005, Van der Graaf Generator reunited. Present was a two-CD set: one disc of songs, and one of in-studio improvisations. It was well received, and the band returned to the touring circuit. But at the end of 2005, Jackson left again, so on 2008’s Trisector, the lineup was reduced to Hammill, Banton, and Evans, as it has remained on 2011’s A Grounding in Numbers and the new Do Not Disturb.

Do Not Disturb begins very quietly, with softly strummed electric guitar and gently smacked cymbals. It’s not until nearly three minutes into the first track, “Aloft,” that the band seems to wake up, as Banton’s keyboards come in and Evans’ drumming revs up—but the production saps much of the song’s impact. The drums have a battened-down, almost ECM-ish subtlety, the keyboard is chintzy when it should be in overdrive, and a guitar riff that should have been doom metal-heavy is instead so underpowered that it sounds like a demo.

The second track, “Alfa Berlina,” is slightly weirder, beginning with real-world sounds, most notably sirens, over Hammill’s dramatically recited phrases (he sounds like a cross between Bruce Dickinson of Iron Maiden and Scott Walker); when the organ and drums come in, he remains just as histrionic. The guitar is kept in the background, and ultimately the track is too subdued by half; Hammill’s ravings are the only thing that make it interesting.

It’s still better than “Forever Falling,” though. That song, the fourth, does allow him to plug in his guitar, and the result is a rote blues riff that sounds like a ’70s boogie-rocker attempting to cope with the arrival of New Wave. When the organ comes back to prominence as the drums go skittery, hearing Hammill sing “Over and over we go through the motions” is almost literally laugh-out-loud funny, given that the song itself sounds like nothing so much as a band of old men acting out “rock” in a futile attempt at vitality.

Two tracks later, he opens “(Oh No! I Must Have Said) Yes” by snarling, “I don’t want to talk about the old days anymore.” Unfortunately, there’s little else to discuss, since the only notable thing about Do Not Disturb is how it seems to treat its title as an aesthetic strategy, and how utterly it fails to measure up to the group’s 1970s albums. Even when they play loudly and aggressively (which they do, at times), there’s a restraint, an unwillingness to upset the listener, at the core of the music. Perhaps it’s just the inevitable consequence of aging. Or perhaps it’s the absence of David Jackson. After all, the last album they made as a quartet, 2005’s Present, had moments every bit as full-on manic as their early work. But the almost frightening intensity that emanated from every moment of The Least We Can Do Is Wave To Each Other, H To He, Who Am The Only One, and Pawn Hearts is utterly absent here. Hammill’s voice is still compellingly weird, but the music he and his bandmates have made on Do Not Disturb is, sad to say, boring.

—Phil Freeman