Despite the tragic loss of Bob Marley last May, reggae continues to expand its influence. A broader and deeper sampling of reggae records than ever before is available in America. Those records reveal the prominent role of the production team of "Sly & Robbie": drummer Sly Dunbar and bassist Robbie Shakespeare. They're responsible for the modern "rockers" style of reggae in which the signature-inverted syncopation becomes more of a throb than a smack. Furthermore, they've flushed out the textures so there's less stop-and-go separations and more harmonic wholeness.

The most successful "Sly & Robbie" project is Black Uhuru. This vocal trio not only has hit singles in Jamaica but its "Red" last year ended up on the 10-best lists of many American rock critics. Black Uhuru's newest album, "Tear It Up--Live" (Mango), is taken from last year's European tour concerts. Much as Bob Marley's live albums were his most dramatic, "Tear It Up--Live" is Black Uhuru's most compelling work.

Michael Rose's lead vocals have a yearning, questing quality but also a disarming conversational tone--a combination that clearly echoes Marley. Duckie Simpson and Puma Jones (an American woman) add dizzying falsetto harmonies at strategic moments to break up the loping, repeating phrases. The backing musicians--"Sly & Robbie" plus the duo's former partners from Peter Tosh's band--are even more impressive. Darryl Thompson's lead guitar cuts threateningly across the ominous throb; Keith Sterling's electric keyboards add nervous pulses. The live audience encourages the singers and players to elaborate expressively on the studio versions.

Unfortunately the powerful music is undermined by Rose's polemic lyrics and attitude. He preaches his Rastafarian creed with little subtlety. The album contains an anti-abortion song and a tribute to Haile Selassie, the emperor of Ethiopia. Would rock critics who praise Black Uhuru praise Bob Dylan if he did an anti-abortion song and a tribute to Anastasio Somoza?

Rita Marley, Bob Marley's widow, was one of the I Threes--his backing singers. She has just released her first American solo album: "Who Feels It Knows It" (Shanachie). In sharp contrast to her husband, she has a light, airy voice that's unusual for reggae. Though it lacks authority, her alto is quite appealing as it skips along with the bright, happy music. She and coproducer Grub Cooper have used very Americanized arrangements with lots of horns and very little drone. The reggae beat becomes a breezy bounce that at first seems slight but soon becomes irresistibly good-humored. The lyrics are simple, psalm-like aphorisms reflected in titles like "Good Morning, Jah" and "Easy Sailing." The hit single tribute to marijuana, "One Draw," is representative of the record's jingly melodic hooks. Musicians from Marley's band and the "Sly & Robbie" team help out.

The Mighty Diamonds sing a Rita Marley composition on their new album, "Indestructible" (Alligator). The Mighty Diamonds have been a top reggae vocal trio since 1975 when they helped "Sly & Robbie" introduce the "rockers" sound. Lead singer Ronald "Tabby" Shaw and partners Lloyd "Judge" Ferguson and Fitzroy "Bunny" Simpson still sing in tight American soul harmonies. "Sly & Robbie" still supply the rhythm though "dance-hall" stylist Augustus Clarke produced this album. The three singers sustain key notes in grainy tenors that blend gorgeously. The mid-tempo sweet music often wraps around hard-hitting political lyrics as in the prison protest of "Tamarind Farm" or the Chairman Mao tribute, "Revolution." Just as penetrating, though, are the affecting reggae love songs, such as the flute-framed "All I Have Is Love." Another Mighty Diamonds album, "Reggae Street" (Shanachie), is due out any day now.

Another reggae album, Jimmy Riley's "Rydim Driven" (Mango), carries an even larger dose of American soul. Produced and backed by the "Sly & Robbie" team, Riley sings songs by Curtis Mayfield, Smokey Robinson and Kenny Gamble plus his originals in the same style. The springing reggae bounce gives soul a refreshing naturalness. Riley hits big climax notes and dramatic asides, while sounding completely informal.

Toots Hibbert has often been called the Otis Redding of reggae. His marvelously expressive baritone voice justifies this extravagant claim on Toots & the Maytals' new album, "Knock Out!" (Mango). He has written six wonderful love songs that woo with an old-fashioned ska beat and seduce with rich melodies. Hibbert, who will perform with the Maytals at the 9:30 club on April 18, is a creative arranger who even throws in pedal steel guitar on the album's one sure classic, "Beautiful Woman." The six love songs give him an opportunity to prove he is the greatest pure singer Jamaica has ever produced. He will savor a line in his rumbling baritone and then jump effortlessly into a giddy falsetto. The album's other three songs concern Hibbert's own religion, the Coptic Church. They prove, at least, that one doesn't have to be Rastafarian to sing reggae.

A new American label, Heartbeat Records, has issued three classic reggae albums here that were previously released elsewhere. The most important release is Linton Kwesi Johnson's 1978 "Dread Beat an' Blood." Johnson is a radical Jamaican immigrant who lives in England. Originally a poet, Johnson wove his patois poetry dub-style (that is, with heavy echo and studio effects) over reggae music. A BBC documentary on him, also titled "Dread Beat an' Blood" has been shown on PBS here. The ferocity of Johnson's anger makes his political poetry and songs compelling if not easy listening.

Heartbeat's other two first releases are "Some Great Big Youth," a welcome anthology of Big Youth's hit singles and best album cuts from Jamaica, and Mikey Dread's "Beyond World War III." Dread is the dub performer and producer who collaborated with the Clash on several dub records. Dread is a studio wizard who uses echo and reverberation for novel effects, but a little dub goes a long way. American audiences are more likely to appreciate the strong emotional singing of Toots Hibbert, Tabby Shaw, Jimmy Riley and Big Youth or the light, happy singing of Rita Marley.