One of the more interesting aspects of stardom is that it tends to feed on itself. Someone who achieves fame in one area of entertainment can often move into another, whether ability is present or not. Thus we have Telly Savalas and Cheryl Ladd singing, Rudolph Nureyev acting, Joan Rivers directing. And we have the Blues Brothers.

Unlike those other examples, the Blues Brothers have talent for their new venture. They also have the best backup band money can buy, an open forum for their antics via NBC's "Saturday Night Live," and enough fans throughout the country to guarantee the commercial success of their first album, "Briefcase Full of Blues."

The Blues Brothers, if you've spent the last year in Siberia, are John Belushi (Joliet Jake Blues) and Dan Aykroyd (Elwood Blues) of the Not Ready for Prime Time Players. But despite their backgrounds as comedians, the pair say they're serious about singing the blues.

To that end, the Blues Brothers have chosen some classic material and adapted it nicely to their own ersatz delivery. They use Otis Redding's "I Can't Turn You Loose" (a hit for the Chambers Brothers) as their opening and closing theme, and cover Sam and Dave's "Soul Man" with a passionate energy.

The more traditional blues numbers are equally hot. "Messin' With the Kid" and "Hey Bartender" have a bombastic intensity and Delbert McClinton's Texas funk gets the full blues treatment on "'B' Movie Boxcar Blues." They even rearrange King Floyd's "Groove Me" into a reggae.

Still, it's very difficult to separate the Blues Brothers' television personalities from their musical performance.

No one is questioning their motives -- they certainly could make more money as Not Ready for Prime Time Players. Nor are they in over their heads. "Briefcase Full of Blues" proves that Belushi and Aykroyd can handle their chosen assignments. The difficulty for the listener is determining just where the seriousness ends and the tangue-in-cheek begins.

By showcasing their act on "Saturday Night," the Blues Brothers have become identified with comedy. Yet they want musical acceptance (they recently took a further step toward credibility by appearing at the New Year's Eve Winterland finale with the Grateful Dead). And "Briefcase Full of Blues" is not a comedy album, nor an attempt at parody. Still, there is some confusion as to just what direction Belushi and Aykroyd want to take.

The record was recorded live at the Universal Amphitheater in Los Angeles, and the duo works the crowd by using their familiar tube personalities. The dialogue between Jake and Elwood is sometimes pretty funny, and anyone who has ever seen the Blues Brothers on television knows that Belushi's crazed dancing is enough to shatter any no-nonsense image the band might have hoped to build.

Also, the vocals sometimes become merely good mimicry. Belushi made a name for himself imitating rock stars like Joe Cocker, and some of his work here lapses into impersonation. On "Soul Man," the Brothers sound like the best group at a high-school "Battle of the Bands" because Belushi sings the song the way he remembers Sam and Dave doing.

Granted, the effort is made superior by Steve Cropper's guitar work and the horn section led by Tom Scott and Tom "Bones" Malone, but the cut is not especially soulful.

The Blues Brothers' comic sensibility also seeps into other areas. "Grovve me" is sung in a Jamaican brogue that's enjoyable, but hardly sincere, and the album jacket photos resemble lineups of armed-robbery suspects. The liner notes by "Miami" Mitch Glazer are also less than straightforward: "There had been too many messy gas station holdups with only some Green Stamps and a case of Valvoline to show for the risk. Joliet Jake had always been full of schemes. But this was different; it played across his tiled cell wall 24 hours a day. And the ending was always the same -- Jake and his younger brother Elwood cruising out of Calument City, Ill., with the sun in their shades and a full tank of gas."

Elwood, by the way, adds to the comedy/drama paradox. His one lead vocal is a bona fide joke called "Rubber Biscuit." Even though Aykroyd contributs a mournful harmonica to the rest of the album, this one moment in the spotlight shows that his sense of humor is never too far from the surface.

Generally, "Briefcase Full of Blues" accomplishes everything it sets out to do. It establishes Belushi and Aykroyd as performers outside the "Saturday Night" for mat; it makes some good blues music accessible to many people who might not hear it otherwise; and it provides the band and the audiences with a rousing good time.

Not surprisingly, the Blues Brothers have vowed to continue. A tour is being planned and more material is being worked out ("Excuyez Moi, Mon Cherie," the flip side of the "Soul Man" single, is not on the album). One question still remains: How long can the Blues Brothers sustain their act once the novelty wears off and they're judged strictly in musical terms?

Until judgment day, though, we can all unabashedly enjoy "Briefcase Full of Blues" for what it is -- a lot of fun.