Former Doobie Takin’ It on His Own : * Music: Michael McDonald brings his new band to Humphrey’s tonight.

Michael McDonald and his six-piece band had just finished playing a cover of Ray Charles’ “Tell the Truth” at the Power Plant rehearsal complex in North Hollywood on Monday night when the studio phone rang. Sounding upbeat, almost hyper, the 39-year-old, blue-eyed soulster promised to get back to the caller after one more run-through of the tune.

It would have been easy to suppose that the keyboardist was upholding his reputation for perfectionism in squeezing a few more minutes of practice out of his charges. But, when McDonald called back, he sounded more like a benevolent musical foreman than an overseer.

“We were just winding down, and I wanted to play the song once more so I could let these poor guys go home,” he offered almost apologetically. The rehearsal was a last-minute tune-up on the eve of a mini-tour of West Coast cities that will bring McDonald to Humphrey’s tonight for two shows.

It seems appropriate that McDonald is including a Charles tune in his current repertoire; the R&B; legend’s influence has been evident in McDonald’s singing, writing, and gospel-blues-ish keyboard-playing ever since he came to fame in the mid-’70s as the leader of the second, funkier incarnation of the Doobie Brothers.

By the end of that decade, McDonald’s distinctive fusing of R&B; and pop on such songs as “Takin’ It to the Streets,” “Minute by Minute,” “What a Fool Believes” and “Real Love” had made him the dominant stylist of the period. Meanwhile, his impassioned, burlap-textured vocals and rugged good looks made him a bona fide, if somewhat uncomfortable sex symbol.

While still with the Doobies, McDonald shared songwriting duties with the others, and the band released albums on the average of one per year. That frequency might have created unrealistic expectations among McDonald’s fans. Since the Doobies’ breakup nine years ago, McDonald has released only three solo albums--1982’s “If That’s What It Takes,” 1985’s “No Lookin’ Back” and last year’s “Take It to Heart.”

Not that he’s been idle. Collaborations with Kenny Loggins, Patti LaBelle, Burt Bacharach and others, and work on film soundtracks and whatnot (he sang the song, “Sweet Freedom” for the 1986 Billy Crystal-Gregory Hines film, “Running Scared”) have kept McDonald fully employed.

Besides, the appearance of intermittent productivity doesn’t overly concern McDonald, who suggested that his comparatively low solo-album output is just a by-product of redirected priorities. That also would explain why he has done a lot of touring over the last several years.

“After I did my first solo album, I just wanted to put together a band that would be right for me,” McDonald said, “and that seemed to take a long time. I really wanted to play live as much as possible, and the process of looking for musicians and looking for gigs probably interfered with writing songs and making albums.

“Ironically,” he continued, “I think my biggest fear was going out and playing live, so I decided to work on that aspect of my career before worrying about releasing a certain number of albums in a certain amount of time. And, quite honestly, I think there was a little bit of laziness involved, too,” he added, laughing.

For someone with an impressive catalogue of hits to his credit, McDonald approaches songwriting with some trepidation. Long ago, he admitted to an interviewer that the creative process is an agonizing one for him, and his struggle to reach a rapprochement with his muse is an indication that McDonald’s fans might have to wait a while for his fourth album.

“If anything, I think songwriting is getting harder for me,” he said, a bit ruefully. “Lately, I’ve just tried to put my head to the wheel, to just write what I can in a day and not think about it too much. I end up hating about 90% of what I come up with, and the rest I save. It’s also tough because we played concerts all last summer and into this spring, and touring like that doesn’t leave much time for writing. I’m just now starting to work on some new material.”

There was a time when you couldn’t turn on the radio without hearing McDonald’s voice, either on his own material or singing background on songs by the likes of Loggins, Stephen Bishop, Nicolette Larson and Christopher Cross. If he isn’t quite as ubiquitous as he was 10 years ago, McDonald established an identifiable style, some facsimile of which seems to pop up every so often.

From Robbie Dupree’s 1980 single “Steal Away”--a blatant, wimpy rip-off of McDonald’s “What a Fool Believes”--to Michael Bolton’s current single, “Love is a Wonderful Thing,” someone has emerged at regular intervals to trade on the McDonald Sound. But, if he notices such things, the ever-gracious singer disavows it.

“Frankly, I think it’s flattering to be compared to someone like Michael Bolton, who I think is a phenomenal singer with a spectacular range,” he allowed. “You know, I’m aware that Michael and I have voices with a certain similar timbre, but I think if there’s common ground between us it’s because we were both influenced by the same people--Ray Charles, Otis Redding, and so on. Anyway, it’s probably a lot easier for others to hear those similarities than it is for me.”

Other than touring with his current band, McDonald said he has no specific plans for the immediate future beyond awaiting the birth of his second child. He has a 3-year-old son, Dylan, by wife Amy Holland--a singer whose 1980 album and its hit single, “How Do I Survive?” were written and produced by her future husband. The McDonalds have lived in Santa Barbara for years, and quiet time spent at home has become increasingly important to McDonald.

“Like everyone else, I have a lot of things I’d like to do that I’ll probably never get around to,” said McDonald, laughing. “But for the most part, I live day to day. I know I need to do more songwriting, but beyond that I’m not making long- range plans. Right now, it’s fun for me to have a career where we work enough to pay the bills.

“Hey, I’d love to have a hit single,” he continued, “but if that doesn’t happen, I’m not going to complain. I have a son who’s a great little guy, and it’s really wonderful that I get to spend a lot of time with him. I’m not too crazy about anything that drags me away from home. For that reason, I think I’d almost dread the day when I got real busy again.

“In fact, maybe I’d prefer to have a lot of career stuff happen a few years from now, when the kids are busy with school and other things.”

Michael McDonald performs shows at 7 and 9 p.m. today at Humphrey’s on Shelter Island.