Reggae fans young and old are invited to the Waikiki Shell this weekend, where the Republik Music Festival holds forth with two evenings of the good vibrations and good times that the music gives off in myriad shapes and forms.

Friday’s lineup features well-established performers who have demonstrated the versatility and freshness of reggae music, with a lineup of Matisyahu and the California bands Tribal Seeds and Groundation.

Matisyahu said he will perform much of the set-list from his 2005 hit album “Live at Stubb’s,” his gold-record-selling album that was named Billboard’s No. 2 Best Reggae Album of 2006. In a surprisingly candid admission for such an accomplished artist, he said he considers it a kind of “make-up” for a 2016 appearance in Honolulu — a performance that in his opinion did not go well.

“It was one of those nights where the sound wasn’t right on stage, the music wasn’t connecting to the audience, and I wasn’t in the right space,” he said. “Sometimes the kind of music I make, where we kind of improvise a lot of the set, sometimes it can take off — and sometimes it doesn’t.

“I felt I wanted to come back and reconnect with people, in a place where they know Matisyahu and fell in love with him in that original space.”

He feels a special debt to Hawaii since that visit actually worked out for the better, due to a chance meeting in a Maui coffee shop where a young man was singing his hit song “One Day.” The two wound up singing a short duet, which went viral.

“There was a little bit of backlash on the internet (from the concert), and then the next day, I was bummed out — and then literally that’s when I walked into the coffee shop, and we left Hawaii with this incredible presence from this random coffee-shop interaction,” Matisyahu said. “It turned into a cool experience, but I still feel that I want to come back and deliver to the fans, who have always been super supportive of me.”

Born Matthew Paul Miller, Matisyahu is a self-trained musician from New York whose upbringing as an Hasidic Jew provided an intriguing counterpoint to the blend of hip-hop, rock and reggae music he was creating. “The music was a way for me to connect with the spirituality, and the spirituality was sort of the instigator in terms of me getting into music in the first place,” he said.

He got into reggae music after visiting his cousins in the Carribbean nation of Barbados, and then hearing the music of Bob Marley. “He became a force of light in my world,” he said. “I started listening to his songs, and that opened up the door to reggae music, which very much piqued my interest in the connection between the Old Testament and being Jewish.”

Sharing the stage with Matisyahu will be San Diego-based Tribal Seeds, led by brothers Steven Jacobo (lyrics, vocals, guitar) and Tony-Ray Jacobo (producer). The band was formed in 2005 and experienced success early and often with its spiritually-driven message and colorful sounds. The band’s most recent album, 2014’s “Representing,” hit No. 1 on the Reggae Charts and spent a week on the Billboard 200.

Groundation is known for mixing in jazzy solos and enticing rhythms into its tunes. That’s not so surprising, since the band was first formed by college jazz band members at Sonoma State University in 1998. Led by Harrison Stafford, the group has reliably turned out albums every couple of years.

SATURDAY EVENING’S bill showcases two big names in reggae, Steel Pulse, and The Wailers, led by bassist Aston Barrett and guitarist Donald Kinsey from Bob Marley’s original band.

Led by David Hinds on vocals and guitar, Steel Pulse is one of the most established names in roots reggae. Still based in Birmingham, England, the group was the first non-Jamaican band to win a Grammy for Best Reggae Album, for “Babylon the Bandit” in 1985. They follow in the grand tradition of reggae as a vehicle for protest and a call for action against injustice.

Just last year, the band released a new album “Mass Manipulation,” its first in 14 years and according to Hinds, one of the most complicated projects the band has ever done. The group had no record label, no studio and no financial backing for the album.

“It meant going on the road and recording in between times where you accumulate the funds to go into a recording studio, across the planet,” Hinds said, “so it’s the first album where the album was recorded in several countries, and several studios within those countries.”

The album sounds as fully orchestrated and rich as Steel Pulse’s music has ever been.

There are seven members in the band – keyboard, lead guitar, rhythm guitar, bass, percussion, two horns providing the brightness the group is known for. “The good thing is that the horn players are very good backing vocalists as well,” Hinds said.

His songs come together organically. He usually starts with a catchy baseline, then the other members begin to improvise their parts. “Sometimes I have to change the baseline altogether once we start hearing it against the vocals, if it starts grinding against the vocals as opposed of working with it,” Hinds said.

As the title suggests, the album “Mass Manipulation” is a comment on social issues. The title track is allegorical, comparing prison with corporate corruption of people’s minds, but there is more direct commentary in the song “Don’t Shoot (Got My Hands Up),” which refers to police brutality.

It is part of the art of good reggae that Steel Pulse can take such unsavory subjects and make them palatable, even appealing to the general public.

“We know there’s a very thin line between a political song and crossing over and not making it to mainstream radio because of the content,” Hinds said, “99.9% of mainstream radio music is not protest of politically oriented. It’s ‘have a good time and get up and dance and who do I make love to next.’ We’re trying to introduce something political into an industry that’s never really accepted it. Those that have are usually underground.”

JOINING THE lineup on Saturday night is Trevor Hall, who is not truly a reggae performer in the conventional sense, but someone who sees his music as fitting in with the reggae ethos quite naturally.

“Reggae music itself is a spiritual music,” he said. “It’s a music that not only sonically is spiritual, it has a rhythm that one can feel in one’s body, and the messages of reggae music have to do with spiritual matters.”

Hall feels the connection with a beach-reggae sound through his roots, growing up surfing in his native South Carolina. He comes to Hawaii frequently and created his 2015 album “Kala” after a visit here.

An avid practitioner of yoga and meditation, Hall has also traveled to India frequently over the last 10 years and has written a number of songs about his experiences there. His most recent album, 2017’s “The Fruitful Darkness,” is an example. The album is a compendium of songs that express dark thoughts like frustration to feelings of optimism and hope.

For Hall, the songs represent one more aspect of the difference in the approach to life in East and West.

“I feel like in Western culture we tend to shy away from the unexplained, the undefined,” he said. “As a Western culture we like to be in control. The things we don’t understand, the things we can’t explain, we tend to push those things away because they remind us we’re not in control.

“But if we look at indigenous Eastern cultures and cultures that base their spirituality as one of the most important reasons we’re here as human beings, all those cultures kind of ‘turn in’ to those spaces. They don’t try to figure them out, they just sit with them and try to learn from them.”

2019 REPUBLIK MUSIC FESTIVAL

>> Where: Waikiki Shell

>> When: 6-10 p.m. Friday and Saturday

>> Cost: $39.50-$65; two-day passes, lawn only, $50

>> Info: 800-745-3000, ticketmaster.com