Devotion to Blues Says a Roomful : R&B;: The veteran band, which plays the Coach House tonight, stays true to its roots, even while collaborating with rock diva Pat Benatar.

People who play the blues for a living usually acquire a down-to-earth realism and a healthy skepticism. They learn to separate possibility from pure fantasy.

As a veteran of more than 20 years with Roomful of Blues, one of the earthiest, most firmly rooted blues bands around, Greg Piccolo presumably knew where he stood in the scheme of things.

The horn-driven Roomful, which shares a bill with Canned Heat tonight at the Coach House, was roots incarnate--the kind of band that would back such seminal R&B; figures as Big Joe Turner, Eddie “Cleanhead” Vinson and Earl King, each of whom recorded a Grammy-nominated album with Roomful during the 1980s.

It was the kind of band that frequently would jam with players like Stevie Ray Vaughan and Jimmie Vaughan, having known and formed a mutual admiration society with the Texas guitarists/ brothers long before they became stars.

Roomful was the kind of band that would cruise the country in a converted library Bookmobile outfitted with bunk beds, traveling thousands of miles a year to fill barrooms with sweaty, swinging, good-time music: straight blues, jumping R&B; and rootsy rock ‘n’ roll.

Roomful was not the kind of band anyone conceivably would want to match with a flashy pop diva like Pat Benatar.

Or so thought Piccolo, a 39-year-old singer and tenor sax player who joined Roomful in 1968 and took over as the band’s leader in 1979. But last August, Piccolo discovered that what seemed to be pure fantasy had turned into a new kind of possibility.

“I got a call one Saturday morning. My wife wakes me up and says, ‘Pat Benatar wants to make an album with you,’ ” Piccolo recalled in a deep, gravelly voice during a recent phone interview from his home in Westerly, R.I. “I just laughed and said ‘yeah’ and rolled over and went back to sleep.”

Eventually, Piccolo woke up to the fact that Benatar, the rock ‘n’ roller with the operatic lungs and sexy image, and her husband, record producer/guitarist Neil Giraldo, were serious about working with Roomful.

“I kept thinking, ‘This can’t be. There’s got to be something more to this than what (Giraldo) is telling me,’ ” Piccolo said. “All I knew (of Benatar) was ‘Love Is a Battlefield.’ I knew they used to call her the Queen of Rock. I’d seen posters of her. I didn’t know she was the person who did ‘Hit Me With Your Best Shot.’ That’s how much I knew about Pat Benatar.”

Strange as it might seem, though, Benatar had decided to make an album of traditional, big-band blues. Piccolo said that she and Giraldo had been searching for the right combination of players last summer when Giraldo came across “Blues Train,” the 1983 album Roomful had cut with Big Joe Turner in a single three-hour session. That, Giraldo decided, was the kind of band he wanted for Benatar’s reincarnation as a blues singer.

So, last September, Roomful’s five-man horn section--Piccolo, baritone sax man Doug James, alto player Rich Lataille, trumpeter Bob Enos and trombonist Carl Querfurth--traveled from Rhode Island with John Rossi, Roomful’s drummer, to serve as the backbone of Benatar’s blues band.

They carried the memory of a previous encounter with marquee names that hadn’t worked out so well: In the late ‘70s, Roomful hooked up for a New York gig with John Belushi and Dan Aykroyd, amid much discussion of possible full-time collaboration. Roomful went into the performance not knowing that Belushi and Aykroyd were looking for a vehicle for their Blues Brothers act that would be more comical than musical.

Piccolo said the gig was an unpleasant surprise for Roomful.

“We got into something we should have known more about before we did it,” he said. “Roomful’s a little more serious than what they did. I’m not knocking it; I guess they did help promote blues music, so in the end it was a good thing. But we just didn’t want to get involved in it.”

No such misunderstandings cropped up during the collaboration with Benatar.

“We felt better and better as we went along, that (producer Giraldo) wasn’t going to pull any weird surprises and make us do any rock songs we weren’t suited for,” Piccolo said.

The album, “True Love,” has shot quickly to No. 40 on the Billboard chart, and the six Roomful members who played on it are getting ready to back her on an upcoming tour (which includes a sold-out date May 22 at the Wiltern Theatre in Los Angeles).

Reviews of the album have been mixed--some praising Roomful’s punchy sound but questioning Benatar’s ability to master material by B.B. King, Charles Brown, Albert King and other straight blues sources. There have been suggestions that Benatar is a mere dabbler in the blues who hired Roomful to purchase some instant authenticity.

“I don’t think that’s true,” Piccolo said. “People are expecting her to sound like what they heard from the ‘50s or ‘40s. I think she sounds like herself, doing these songs the way she feels them. And that’s the way you have to do it when you do anything. I think she’s only going to get better at it. She’s a good singer, and the more she does (the blues), the more she’s going to get into it.”

Piccolo said one of his main concerns in making the album was working with a guitarist--Giraldo--who didn’t have a track record as a blues player.

“I was very concerned about that,” Piccolo said. “I didn’t know anything about him as a guitar player. I thought, ‘He’s probably one of these guys who goes berserk, playing in a rock band.’ But he does have the right attitude--that basic, simple approach, and that’s what you have to have to pull this stuff off.”

The high-profile alliance with Benatar and Giraldo comes at an opportune time for Roomful. Since the mid-1980s, when the success of such performers as Stevie Ray Vaughan, the Fabulous Thunderbirds, Los Lobos and the Robert Cray Band made it clear that blues bands could reach a mass audience, Piccolo has been eager for a share of that mainstream acclaim. Roomful, he said, is almost finished with a new album that Giraldo is producing with an eye toward landing a major label deal.

It would be the band’s first studio release of its own new material since 1984’s “Dressed Up to Get Messed Up” (in 1987, Roomful issued a live album of its own, as well as “Glazed,” its collaboration with New Orleans R&B; master Earl King).

“We haven’t put out any product on purpose,” Piccolo said, “because we haven’t gotten the deal we wanted. I swore I would never do another record of original material for a small label. I believe in what I write in a big way; if I put out original songs, I want them to be pushed. I’m hoping (the new material produced by Giraldo) is going to open it up for Roomful to get the deal we’ve been waiting for for quite a few years.

“We haven’t held out in vain,” he added. “Things are looking very good for us now. I think our name already got more exposure in the past two weeks than in the 20 years of Roomful.”

Last year, while waiting for a major label break to materialize for Roomful, Piccolo put out an album of his own--”Heavy Juice,” on the blues label Black Top--that paid homage to his R&B; sources. The album reunited him with Al Copley, Roomful’s original piano player, and Duke Robillard, the guitarist who founded Roomful and fronted the band through its first decade.

Roomful has proved to be an incubator for a wide assortment of blues talent: The players who succeeded Robillard and Copley, guitarist Ronnie Earl and pianist Ron Levy, also graduated to careers of their own. Fran Christina and Preston Hubbard, longtime drummer and bassist of the Fabulous Thunderbirds, also started out with Roomful. Robillard now is a T-Bird as well, having taken over a guitar slot when Jimmie Vaughan quit the band last year.

Roomful’s current soloists are guitarist Chris Vachon and pianist Junior Brantley. Larry Peduzzi, who was part of the original 1967 Roomful lineup, is back on bass after a long absence. Since Benatar is only using six Roomful members on her tour, Piccolo said he’ll keep the whole band busy by lining up some after-hours club dates along her touring route.

Even if the Benatar association gives Roomful a boost, Piccolo doesn’t see any fundamental changes in the way the band operates, including its schedule of more than 200 live shows a year.

“Everything we do is pretty much contrary to the way people do things in the rock world,” Piccolo said. “Pat Benatar is going to go on tour for a couple months, and that’s going to be it until the next project. Roomful is just one constant project. We’re going to play every week, because this is what we do. It’s blues, and what you’ve got to do to play blues is work all the time. We never thought about not working. It’s out of the question.”

Roomful of Blues and Canned Heat, featuring guitarist Harvey Mandel, play tonight at 9 at the Coach House, 33157 Camino Capistrano, San Juan Capistrano. Tickets: $17.50. Information: (714) 496-8930.