THE ALBUMS TOM WAITS, Blue Valentine (Asylum 6E-162). LEON REDBONE, Champagne Charlie (Warner Bros. BSK 3165). THE CONCERT TOM WAITS & LEON REDBONE, Tuesday at 8 at the Warner Theater. Tickets $7.50, reserved.

This Tuesday Washington will be treated to as most eccentric show since the Nixon administration. Tom Waits and Leon Redbone will be at the Warner Theater, two cult heroes for the price of one. The concert will also offer an opportunity to explore two radically different approaches to American contemporary music.

Waits' work is the aural equivalent of a Raymond Chandler novel; you catch the same chill from both. Waits doesn't sing so much as growl through compositions that contain more short story than melody. Though not yet 30, he spits out timeless themes of isolation, depression and dreams gone sour. Not exactly Seasame Street.

He draws scenes from dark alleys and pool halls and the ambiance he creates forms a type of music noir . Your nose almost begins to run from the imagined rawness of the night. As soon as Wait's gravel pit of a voice begins to sketch another figure from the shadows, the fog rolls into your mind the way it rolled into the final airport scene in "Casablana."

"Blue Valentine," Waits' latest effort, is a continuation of the angst he began in "Closing Time" and has worked on through five succeeding albums. In those terms, "Blue Valentime" is more satisfying than "Small Change" and not quite as strong as "Foreign Affairs." For atmosphere, though, it's better than the Nixon-era Sans Souci.

The Album opens with "There's a Place for Us" from "West Side Story," and the menacing hiss that Waits manages to punch through the orchestral arrangement leads the listener to believe that this could only be the work of amdman. Luckily, once the final chord has faded into the mist, the true Tom Waits surfaces desolate, angry and a little frightening.

Just as in most other Waits efforts, we are sucked into the erie world that he creates with a masterful blend of blues vocal phrasings and scat, accentuated by a jazz combo backup. His lyrics can be lurid, but he emotion behind them is affecting.

"Red Shoes by the Drugstore" talks about a girl waiting in the rain for her murdered lover. "Christmas Card From a Hooker in Minneapolis" is a first-person reminiscence tinged with gallows humor. The title cut is a love lament so desperate tht it should bring out the social worker in everyone.

The entire album is filled with rain and police sirens as Waits paints pictures of neighborhood big shots who are all dressed up with no place to grow. The two most powerful pieces, "Romeo Is Bleeding" and "Kentucky Avenue," are examples of life at its most constricted. The characters that people Tom Waits' songs are prisoners of their environment and their own mental paralysis. The basic needs expressed in "Romeo Is Bleeding" point out the frustration of confused youth: "And Romeo says hey man gimme a cigarette / and they all rach for their pack / and Frankie lights it for him and pats him on the back . . . / and they all know they could be just like Romeo if they only had the guts."

The Illustrated Encyclopedia of Rock calls Tom Waits "a cross between Lord Buckley and Jack Kerouac," but his childhood in Pomona has given him the perspective of Nathanael West. From that base, he's developed a growing number of loyal followers, but it's for granted that Waits is not going sell a whole lot of records.

Most people feel that he's too seedy, too bizarre, too unmelodic. What he really is is too threatening.

Where Waits is threatening, Leon Redbone is almost comical. His is an art of another color. Redbone is the guy with the handlebar mustache who was the biggest thing to hit NBC's "Saturday Night Live" since Steve Martin. Redbone's music sounds as if it should be hear over the radio, between "The Shadow and "Fibber McGee and Mooly," but he's managed to achieve a degree of stardom with interpretations of tunes like "Shine On, Harvest Moon" and "Polly Wolly Doodle."

Redbone can truly be termed a "Character," and the one he chooses to play is part Mississippi riverboat gambler and part vaudeville warnup act. He's managed to keep his personal life obscure (even the Warner Brothers information sheet doesn't list a birthplace or date) while making his musical idols accessible to a new generation of listeners.

On his latest release, "Champagne Charlie," Redbone performs compositions by Jellyroll Morton ("If Someone Would Only Love Me" and "I Hate a Man Like You") and Jimmie Rodgers ("T.B. Blues"), as well as snappy renditions of "Alabama Jubilee" and "Please Don't Talk About Me (When I'm Gone)."

Redbone's influences on "Champagne Charlie" are the same as on his previous two albums: country guitarists like Big Bill Broonzy and Lonnie Johnson and melodic masters like Fats Waller. This album has the same tongue-in-cheek delivery and subtle appeal of his earlier releases, and it also serves as an archive for the preservation of some musical treasures.

Neither Redbone nor Waits will ever fill a large arena or have a platinum album - but neither really needs to. Though their forms of expression exist in the twilight of today's popular music, their impact ripples through the mainstream.

At the very least, Tom Waits and Leon Redbone should be heard, if not seen. Tuesday, it would be a good idea to do both.