Van Halen was pretty much all business Friday at the sold-out United Center, and that’s saying something when that eternal hedonist, David Lee Roth, is involved.

The ’70s metal giants are back with three-quarters of their original lineup, with Eddie and Alex Van Halen joined by Eddie’s 20-year-old son, Wolfgang, on bass. They were an impressive power trio, throwing up a brick wall of sound with the youngest Van Halen in particular stepping up his game. On a 2007-08 tour, Wolfgang was an understandably timid teenager replacing band cofounder Michael Anthony. On Friday, his vocal harmonies were strong and sure, and his bass playing was agile enough to slip between Alex’s stampeding kick drums and Eddie’s slaloming guitar leads.

On a spare stage, backed by a wall of amplifiers and an IMAX-style video screen that essentially blew up the on-stage proceedings to Godzilla proportion, the band slammed out 24 songs in two hours. No fuss, few frills, only a confetti shower for the closing “Jump.” With the exception of some piped-in keyboards and a rhythm guitar track on one song, the band did all the heavy lifting itself. This was the kind of ballad-free heavy that suggested a grand piano being dropped from a 20th-floor window, closing in on the pavement with intimidating size and speed.

Sometimes it looked a little too much like work, especially for the normally flamboyant Roth. He entered with a scarf-and-glitter outfit befitting a circus barker and a broad grin. But he was soon complaining about the weather conditions (“There’s some kind of blower … shut it off!”), his microphone, the need for a water bottle – he was distracted presence for most of the show. Once a showman who was as much about acrobatics as singing, Roth focused exclusively on the latter this time.

He moved stiffly, without much bravado. No jumping, strutting, preening – compared to his former jive-talking, jive-walking self, he was positively inert. Instead, he tried to point his voice in the right direction, and about half the time he nailed the high notes. Otherwise, he sounded ragged and strained. It’s early in the tour, but you have to wonder how well his voice will hold up two months down the road. Or his attitude. In the future, he might try spending more energy on his performance than chewing out the band’s roadies.

Only a handful of tracks from the quartet’s latest album, “A Different Kind of Truth,” infiltrated the classics-heavy set list. With their shout-along choruses, “Tattoo” and “She’s the Woman” sounded pretty much like the old Van Halen, and why not? Several of the “new” tunes were recycled from the band’s early demos. What the fans paid to hear were the likes of “Ain’t Talkin’ ‘Bout Love,” “Runnin’ With the Devil” and “Panama,” which endure as flashpoints for a generation on familiar terms with shag carpets and boogie vans. Not everything has aged as well, though. “Hot for Teacher,” for example; it’s difficult to defend that one remaining on the play list now that Roth is no longer in spandex.

Still, even the tritest songs had Eddie Van Helen playing on them, and that’s almost always a good thing. After a decade of health problems and intra-band struggles, he looked and sounded rejuvenated.

Near the end of the set, he commanded the stage by himself for seven minutes. First he flopped down on the stairs leading up to the drums like a kid in his bedroom: a boyish grin, jeans, gym shoes, and his guitar. He tap-danced on the strings, then drifted off into a space odyssey that suggested a soundtrack for an unmade science-fiction movie. He swiveled, wielding the guitar like a weapon, emitting a low, moaning chord that reverberated around the arena. He’s that rare ’70s guitar icon who still sounds like the future.

Sometimes it looked a little too much like work, especially for the normally flamboyant Roth. He entered with a scarf-and-glitter outfit befitting a circus barker and a broad grin. But he was soon complaining about the weather conditions (“There’s some kind of blower … shut it off!”), his microphone, the need for a water bottle – he was distracted presence for most of the show. Once a showman who was as much about acrobatics as singing, Roth focused exclusively on the latter this time.

He moved stiffly, without much bravado. No jumping, strutting, preening – compared to his former jive-talking, jive-walking self, he was positively inert. Instead, he tried to point his voice in the right direction, and about half the time he nailed the high notes. Otherwise, he sounded ragged and strained. It’s early in the tour, but you have to wonder how well his voice will hold up two months down the road. Or his attitude. In the future, he might try spending more energy on his performance than chewing out the band’s roadies.