POP WEEKEND : Ho-Hum Evenings With Some Rock Stars From the Past : Todd Rundgren: His singing contained blatantly awful moments of hawing and screeching and shrilling and rasping.

“Something/Anything” was the title of the album that made a pop hero out of Todd Rundgren 18 years ago, but “Sincerity/Irony” is the juxtaposition that defines his career in general and his show Saturday night at the Celebrity Theatre in particular.

One doesn’t often hear a song as splendidly serious and sincere as “Hawking,” the emotional high point of Rundgren’s rambling 2 1/2-hour concert. Inspired by physicist Stephen Hawking, the song is about reaching and searching for knowledge and ideals that lie beyond mortal bounds.

That interest in reaching and searching extended to Rundgren’s whole singing approach. Always a great admirer of soul music’s vocal heroes and their free-flying explorations, Rundgren seemed committed to pushing his voice into their rarefied sphere.

The problem is that the tone and color of Rundgren’s voice is thin and pale, not rich and robust. There was something admirable and sincere in his repeated attempts to soar on clipped wings. But the effect was often ironic instead. Rundgren may sing in the pattern of Marvin Gaye, but he’s no Marvin Gaye.

Consequently, Rundgren’s singing contains blatantly awful moments of hawing and screeching and shrilling and rasping that occur when his four-cylinder voice balks as he tries to push it up a grade that demands a vintage Motown V-8. Anyone willing to expose himself to moments like that can’t be taking himself all that seriously, so Rundgren’s style displays a sense of humor and irony at the same time that it signals high, perhaps foolhardy ambitions. (Rundgren mocked his own soul-man aspirations toward the show’s end when a roadie ran out and draped a regal cape over him, in a burlesque of a James Brown stage climax.)

The problem is that the point of soul singing is to sound wonderful, and when Rundgren stretches his voice too far he sounds anything but. Instead of tripping over tropes that are beyond him, one wishes that Rundgren would rein himself in and stay within the (fairly extensive) range where he sounds solid and comfortable. It’s a fine thing to search and reach for things beyond one’s grasp, but recognizing one’s limitations is an achievement, too.

Few songs in Rundgren’s sprawling concert were as gripping as “Hawking.” For the most part, the show, which could have been profitably pruned of 30 to 45 minutes, maintained a low-keyed appeal. He shied away from rockers and hits, and concentrated on ballads, mid-tempo, soul-flavored songs, and material from his recent album, “Nearly Human.”

The performance was enjoyable in a relaxing, excursion-like way: one could just sit back and take in the consistently sharp playing and singing of Rundgren’s 11-piece backing ensemble, grin at the many sight gags and wry asides, and sit up and take notice when things got more intense on songs like “The Want of a Nail.”

At a time when most of his over-40 peers in rock have been rolling out their biggest hits on megatours, Rundgren shunned career retrospective. Plucking just one oldie, “Hello It’s Me,” from “Something/Anything,” he skipped most of the better-known songs that non-cultists would probably want to hear.

If being a cult artist is a limitation, then it was a limitation that Rundgren seemed happy to accept. In this instance, playing for a cult, rather than members of a less committed mass following, gave Rundgren the freedom to skip the blockbusters and follow his inclinations before an audience that didn’t demand the obvious.

A good many of those less obvious songs unfolded quite nicely, including all of the “Nearly Human” material other than the overdone gospel-rave-up finale, “I Love My Life.”

Pleasing somebody else’s cult followers is always a tough proposition for an opening act, especially a solo acoustic act, but Orange County folk-rocker Vinnie James held the early-arriving Rundgren fans with a commanding performance.

James’ debut album, “All American Boy,” will feature a roster of all-star accompanists when it arrives in April (among them are Benmont Tench and Kenny Aronoff), but James showed enough fire and presence to make an impact on his own, despite a thin, tinny guitar sound that undermined his aggressive strumming.

James’ best assets in a half-hour set were a bluesy voice that was gritty yet supple, and a sequence of songs that had points to make without stinting on melodic appeal. “Black Money,” with its aching and angry overview of the drug scourge, was especially gripping. James, who thinks on a big scale, amplified the song’s point by pausing afterward to castigate the tobacco industry, telling the audience that his chain-smoking mother is about to undergo brain surgery brought on by lung cancer.

“Cigarettes are drugs,” he said.

James was a bit tentative in some of his other remarks and stage mannerisms (an anecdote about bowling that introduced “All American Boy” didn’t quite come off, nor did what appeared to be a facetiously intended but half-heartedly executed Chuck Berry duck walk during the song).

But James has the basics covered: he earned his good reception with the sure and forceful rendition of strong material.