A recent unscientific study of commercially purchased Comets on Fire albums (OK, the "whiff test" at several friends' places) has concluded that 94 percent of the jewel cases housing these discs bear the unmistakable scent of regular stem-and-seed separation operations. Marijuana, people. Blue Cathedral, the third album from this blazing psychedelic Santa Cruz, California, quintet, will almost certainly continue that trend with its chaotic take on classic head-trip garage-blues. How serious is COF about blowing minds with guitar-heavy freakouts? The band has a guy whose sole role is to man the echoplex, a vintage tape-delay unit that adds extra layers of noise and dementia to tracks like the wild, eight-minute opening ride "The Bee and the Cracking Egg" and the brain-cleaving "The Antlers of the Midnight Sun." (The latter is sure to splatter vivid, solar trails on the backs of your eyelids.) Oh, and vocals? Yeah, there are some vocals before the extended instrumental jams take over, but when he does sing, frontman Ethan Miller's banshee howl sounds like a bare-chested Robert Plant attempting to wail in Welsh with a mouthful of groupie naughty bits. Cathedral offers points of relative calm, too: The two-minute "Organs" and the organ-driven "Brotherhood of the Harvest" set the controls for the heart of the bong with a swirly, interstellar vibe that, er, echoes Pink Floyd's "Echoes." And the balmy, haunting "Wild Whiskey," with its almost-sitarlike acoustic guitar and tribal percussion, could easily play behind the misty river scene in Apocalypse Now when Willard finally arrives at Col. Kurtz's eerie jungle outpost. Put together, it's another fantastic outing for Comets on Fire, enjoyable at 4:20 p.m. or any other time of day.