POP MUSIC: ROCK, COUNTRY, R&B;, RAP, LATIN, JAZZ : Sliding Out of the Crossroads : Were blues, reggae and hip-hop meet, you’ll find Ben Harper with an acoustic guitar and a heart full of soul.

A look of concern briefly crosses the face of singer-guitarist Ben Harper as he takes a phone call from Vancouver in his Hollywood apartment. Is this guy actually making him an offer to perform “Oh, Canada” for thousands of pro basketball fans?

No, it turns out.

It’s soon clear that the caller is looking for someone to play the U.S. anthem before a game by the Grizzlies, the new Vancouver entry in the NBA.

Harper’s face brightens at the prospect of playing “The Star-Spangled Banner,” the tune Jimi Hendrix, one of his heroes, once recast into his own wild, expressionistic image in the waning moments of Woodstock.

“That’s deep,” says Harper, contemplating his own possible rendition on acoustic slide guitar. “That’s tremendous.”

This time, he’ll have to pass on the invitation.

The 26-year-old singer-guitarist already has the next three months on the road booked solid, including his second headlining show at the House of Blues on Jan. 23.

What’s keeping him busy is the charged mix of blues, funk, folk and hip-hop of his “Fight for Your Mind” album, his second for Virgin Records.

On the tracks “Ground on Down” and “God Fearing Man,” Harper presents agitated, ominous slide guitar from a place where Hendrix meets Robert Johnson. And his lyrics--soulful messages on hope, love and redemption--follow the example of reggae legend Marley.

“The thing about him is that his music is very earthy,” says Merilee Kelly, music director at adult alternative station KSCA-FM, which has included Harper on its playlist since “Welcome to the Cruel World,” his 1994 debut. “He’s a very gentle soul, but he has a lot on his mind and it’s very powerful. It makes you stop and listen to both the music and the lyrics. That’s rare.”

Those lyrics sometimes take on themes of self-worth and social justice a la Marley on the songs “Oppression” and “Excuse Me Mr.” Elsewhere he explores troubled romance, or a bold spirituality via “Power of the Gospel,” where a quietly emotional Harper sings with his acoustic guitar set against the subtle power of a string quartet.

“A preacher is someone who tells you what to believe,” Harper explains. “I just tell you what I believe, and I believe in betterness and the power of music. Music is the only way I know, man, to reprimand the wicked and bring betterness to the Earth.”

Harper is relaxing on the balcony of his apartment, which is scattered with traveling cases, clothes and guitars. A row of weathered skateboards rests by the front door, and the walls are covered with images of Hendrix and Marley. On his right hand, Harper wears a ring bearing “the Lion of Judah,” a symbol of Marley’s Rastafarian religion.

“Listening to Hendrix took me to other places, faraway places,” says Harper, his bearded face flanked by two tight braids. “Hendrix’s guitar playing, Marley’s lyrics and music--this is all proof to me of a greater force on life upon Earth than man.”

But his own sound goes beyond the blues-rock and reggae of those heroes to include the aggressively contemporary beat of hip-hop, if sometimes only subtly blended into the mix.

“I feel a lot more sincerity in the majority of hip-hop today than folk and almost any other music,” Harper says. “It just seems to be coming from a lot truer place. The rhythms and grooves are so stickin’ and so hard.”

Consequently, Harper has little patience for the modern generation of blues slide guitarists who master the standard blues leads and progressions at the expense of a personal musical voice.

“I just knew I didn’t want to sound like that, and it frustrated me when I did,” Harper says. “I used to really lose sleep over it.”

Harper found a solution by abandoning standard bottleneck playing for some experimentation on a borrowed lap guitar.

“I laid that sucker down, and instantly a tuning came to me. I started strumming it and I said, ‘Yeah, this is it. This is different.’ ”

While he’d discovered a new sound that inspired a sudden flood of songwriting, his new instrument meant he would be spending his time on stage sitting down. The absence of the old guitar-hero poses left some of his early audiences disconcerted.

But the fans seem to have adjusted.

At his appearance at the House of Blues last year, Harper was repeatedly moved to rise from his chair during solos by members of his band, which he’s named the Innocent Criminals.

“He’s one of those people who can really galvanize a crowd,” says James Lien, music editor at the influential College Media Journal. “He’s real quiet and introspective, but he’s got a real charisma about him.”

Harper’s manager, J.P. Plunier, who also produces his records, suggests that the guitarist “is levitating anyway. The chair could not be there and it wouldn’t matter.”

“A lot of people try to do what he does stylistically, by the way they dress or play, but that isn’t what it is about,” Plunier adds. “Those things are gifts. Those things are given to you.”

The roots of Harper’s music came naturally to him while he was growing up in the Inland Empire, spending his days at the Folk Music Center, the Claremont music store and museum that his grandparents opened in 1958. At home, his parents kept the turntable busy with records by such early Delta blues artists as Robert Johnson and Son House, along with newer discs by Hendrix, Marley and Otis Redding.

By age 9 Harper was playing drums, but he soon dived seriously into guitar when he discovered the power of Hendrix. In high school he was attracted to the hard rhythms and precise vocal phrasings of such rappers as Run-DMC and LL Cool J, but his interests weren’t always shared by friends.

“I used to play guitar and my friends would laugh at me: ‘What is that?’ It wasn’t cool to be behind an instrument, man, to be a brother,” Harper says now with a laugh.

“That’s how hard-core the world of hip-hop is. Playing an instrument was almost like selling out. Listening to anything but hard, straight-ahead hip-hop was unheard of.”

He’s glad to now see jazz emerging as a major element of the hip-hop blend, building his own groove-heavy music with an acoustic guitar.

“Music has changed my life, man,” he says. “Music is the most powerful form of communicating truth. Music can’t lie, especially blues music. Blues music only knows truth. That’s the beauty of it.”

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BEN HARPER, House of Blues, 8430 Sunset Blvd. Date: Jan. 23, 7:30 p.m. Price: $15. Phone: (213) 650-1451. Also, Jan. 27 at the Galaxy Theatre, 3503 S. Harbor Blvd., Santa Ana, (714) 957-0600.

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Piece of ‘Mind’

* To hear a sample of Ben Harper’s album “Fight for Your Mind,” call TimesLine at 808-8463 and press *5710.

In 805 area code, call (818) 808-8463.