ROCK REVIEW : Rap Concert Fails to Sizzle in San Diego : Music: Although it included a brawl, the Sports Arena concert seemed to lack steam and could not keep the under-capacity audience energized.

Rap is not a critics’ music; it is a disciples’ music. This was conclusively demonstrated Sunday night when a rap revue calling itself the ‘Sizzling Summer Tour ‘90’ played its final engagement at the San Diego Sports Arena before a less-than-capacity house.

For almost five hours, devotees of the Afros, Queen Latifah, Kid ‘N Play, Digital Underground, Big Daddy Kane, and headliners Public Enemy were jerked into spasmodic movement by what seemed little more than intermittent segments of a single rhythmic continuum. It was hypnotic in the way of sensory deprivation, a mind- and body-numbing marathon of monotony whose deafening, prerecorded drum-and-bass tracks and roving klieg lights frequently turned the audience of 6,500 into a single-minded, moveable beast.

Funk meets Nuremberg Rally.

Although subtlety is not rap’s long suit, the form has undergone some crafty changes since a seminal caravan featuring Kurtis Blow, Run-D.M.C., the Fat Boys, Newcleus and Whodini hip-hopped into town in December of 1984. Perhaps in an unwitting acknowledgement of its own limitations, rap began expanding its aural base by electronically cannibalizing recordings of other music (via a technique known as digital sampling), to spice up an otherwise tedious sound.

As snippets of sampled guitars, horns, keyboards, drums and even vocals began contributing textural dimension to the rap mix, the pummeling rhythms that are its foundation became increasingly complex. In its most evolved form, today’s hip-hop rhythm track is a drive-shaft of propulsive interlocking accents and sounds. In such cases it has the appeal unique to sophisticated, polyrhythmic music.

In the last couple of years, critics who have noted both rap’s musical maturation and the social relevance and cleverness of its best lyrics have been jumping, sometimes clumsily, onto the rap bandwagon. Public Enemy’s current “concept” album, “Fear of a Black Planet” --a cauterizing overview of the issues facing black America--has even been hyped as “a pop masterpiece.” And the seven-member Digital Underground has made friends in the media with its imaginative lyrics and self-parodying, costume-party high jinks.

I ventured to the Sports Arena, then, reasonably hopeful that I was in for an altogether different experience than the silly, chest-thumping spectacle I’d witnessed at the same venue six years before. It was different, to be sure, but not in the ways I had expected. For one thing, the earlier revue sold out the arena, and the throng on hand that wintry night maintained a frenzied involvement throughout. Besides falling far short of a sellout, Sunday’s audience seemed like a huge battery that needed regular, periodic jolts to keep it functioning.

Unfortunately, the rappers’ jumper cables were old and worn: profanity, taunting exhortations, and lascivious braggadocio designed to fan the basest impulses. One could conclude that rap hasn’t become more “adult” in the sense of mature insights but in the manner of XXX-rated movie houses. Still, even the most provocative of inducements had a limited effect. The momentary gratification that is both rap’s allure and its Achilles heel was exemplified by the rapid ebb and flow of the crowd’s enthusiasm.

In an inversion of normal concert behavior, fans would cheer madly at the introduction of each act, but would muster only a fraction of that noise at the act’s departure. Similarly, the shared energy with which each ‘jam’ began had almost completely dissipated by its conclusion.

The overtly sexual, frequently misogynistic turn that has gotten rap into well-publicized trouble of late was represented in the blessedly brief opening set by CBS Records’ newest aspirants, the Afros. Wearing white-rimmed shades and oversized Afro hairdos (wigs?), emcees Hurricane and Kool Tee paced the stage like drunken sentries, spewing the senseless rhyme of “Hoe Cakes (For My Ho’),” in which “bitch,” “whore” are recurring themes.

Meanwhile, a peripheral member of the loosely defined group silently held aloft enlarged photos of established black performers, including the Jacksons, Stevie Wonder and Sly Stone. If this was an attempt at drawing a connection between these superstars and the Afros, it backfired in its encouraging listeners to make on-the-spot, qualitative comparisons.

Queen Latifah followed with a more enjoyable set that included the politely feminist ode, “Ladies First.” The rap artist’s distinction is an inclination to end long stanzas of rap rhyme with a sung refrain that has African-chant overtones. She has a fine voice, and one perceives in Latifah a secret desire to be a singer in the more traditional mode.

The duo Kid ‘N Play easily were the best dancers among the show’s emcees (several acts had attendant hoofers), and their acrobatic, synchronized moves during the aptly-titled “Energy” (flip-side of their latest single, “Back to the Basics”) were astonishing. Unfortunately, their performance quickly degenerated into childish pandering. In one particularly crude bit, the two took turns humping the stage in a challenge to see which was more adept at “pleasing a woman.” Naturally, this boys-room naughtiness elicited loud, hooting approval.

Digital Underground was a disappointment, but one that provided some amusing distractions. Led by front-mouth Humpty Hump--a guy who wears a suspiciously shaped nose prosthesis--DU specializes in the type of skewed word play and fractured antics that evoke George Clinton’s ‘70s clown-funk conglomerate, Parliament/Funkadelic. Performing material from their acclaimed album, “Sex Packets,” Hump and two outlandishly outfitted sidekicks squirted champagne at the audience from crotch-level bottles and, standing single-file, simulated various sex acts with inflatable dolls. Then two of the emcees stripped to G-strings to continue the pantomime on the stage floor. How exciting.

After the house lights were brought up following DU’s exit, a fight broke out in front of the stage. Security guards, members of various rappers’ entourages, and fans joined in a fray that grew to mob size and then pushed into a corner of the floor at one side of the stage. People rushed the area from all parts of the arena, but the scrappers were so tightly balled together that few serious punches could be thrown, and, in a few minutes, a tussle that threatened to become a small-scale riot instead lost steam.

Genuine action of this sort made Big Daddy Kane’s subsequent macho strutting seem ludicrous by comparison. Although he includes stern, well-intentioned admonitions in his lyrics (“stop smoking and get an education!”), Kane’s shtick is dominated by sex-boasting (“Cause I Can Do It Right”) at its most puerile. His set was a complete bore, except to those with a special appreciation for public rest-room graffiti.

Given the dirty-magazine mentality that reigned during the others’ sets, Public Enemy’s hard-core politics promised a welcome respite. The tone of its performance was set long before PE appeared. Stage hands erected a huge, yellow-and-black Public Enemy banner above the back risers, and flanked it with reproductions of the crew’s logo--a human silhouette caught in the cross-hairs of a rifle sight.

The stand holding the DJ’s two turntables formed a lighted, red “X.” This might have seemed only a reference to the DJ’s stage-name (Terminator X), but given the group’s politics--and especially the presence of a cadre of suited and bow-tied Black Muslims silently drilling and saluting in the stage’s shadows--the large red letter brought to mind a possible tie-in with the memory of Malcolm X.

PE’s emcees--Chuck D and Flavor Flav--were preceded onto the fog-shrouded stage by four guys dressed in white naval-officer uniforms and four others in dark, paramilitary duds. The first of these quartets did martial-arts moves as D and Flav pranced and exhorted through the incendiary lyrics of such jams as “Anti-Nigger Machine,” “Who Stole the Soul?,” and an interminable version of the anthemic “Fight the Power.” Toward the end of the show, the “officers” changed into camouflage fatigues and brandished fake Uzi machine guns to underscore PE’s militant message.

The crowd’s response to PE was immediate and sustained, and was driven to a peak by Chuck D’s mid-set monologue about racism and the oppressive American government. D made several good points that drew loud accord. “When a government starts worrying about things like art and obscenity,” he shouted in reference to the recent legal problems of the rap group the 2 Live Crew, “it’s just diverting people’s attention away from more important issues, like poverty, homelessness and joblessness. It means the government’s not doing it . . . job!”

But D’s complaint that the media are aligned against him was both specious and evasive. Critics have practically lionized Public Enemy, and their publicizing of the group’s political harangues and the controversy they have spawned is at least partly responsible for the fact that “Fear of a Black Planet” has sold in the millions.

PE’s employment of intricately layered aural effects is one reason the critics love them. In concert, however, the group’s sound settled into a bludgeoning clamor enlivened only by the spoken interludes. Any act that relies on controversy to maintain interest is on shaky ground. And any cultural form that can’t generate enough of that interest to fill an arena at the height of such controversy might be counting its days.