Both the Beach Boys and “The Beach Boys” — the new documentary dropping Friday on Disney+ — are all about blending a range of voices.

The three Wilson brothers — Brian, Carl and Dennis — along with cousin Mike Love and friend Al Jardine, brought a harmonic revolution to group vocals with their Southern California sound that brightened the 1960s with songs like “I Get Around,” “Good Vibrations” and “God Only Knows.”

In his documentary on them, director Frank Marshall took oft-told tales of the band’s six decades of heartache and harmony, and tried to make them broader, and brighter, by mixing as many voices as possible.

“It was the blend of everything,” Marshall told The Associated Press in a joint interview with Love and Jardine at a Hollywood recording studio. “It’s the blend not only of the family story, but the blend of the harmonies. If you took one element out, you wouldn’t have the Beach Boys.”

The 83-year-old Love said Marshall’s project was “a monumental effort” for all involved and that they’ve “never done so much promotion in our entire lives.”

“This fella here, Frank, is able to take all that ridiculous amount of information and make it into a coherent, wonderful, documentary that really gives not only a look into the individuals, but the collective impact,” he said.

The film includes extensive new interviews with the singer Love and singerguitarist Jardine, 81. And it draws from many archive interviews to give the perspectives of singer-guitarist Carl Wilson, who died from cancer in 1998 at age 51, singer-drummer Dennis Wilson, who was 39 when he drowned in a Los Angelesarea harbor in 1983, and their older brother Brian, mastermind of the band’s sound.

The 81-year-old Brian Wilson makes current-day appearances in Marshall’s film, including in an emotional scene at the coda whose details remain best unspoiled. But the mental decline that recently led to his loved ones establishing a court conservatorship for him left his contributions limited.

Often, the media admiration of the group’s music focuses entirely on the eldest Wilson boy with what many consider his unmatched musical imagination and innovation. Marshall’s documentary does nothing to downplay his genius, but emphasizes he was not alone.

It is rarely acknowledged, for example, that Love wrote the lyrics to dozens of songs, including “I Get Around,” “California Girls,” “Help Me Rhonda,” and the sweetly poetic “Good Vibrations,” penned in the car on the way to the recording session: “I love the colorful clothes she wears, and the way the sunlight plays upon her hair.”

The Wilsons’ father and early band manager Murry Wilson, in one of many moments of mismanagement depicted, sold the Beach Boys’ song catalog for $700,000 in 1969 without consulting the band members, and left Love’s name off as a contributor.

“That’s rough,” Love told the AP, “when your uncle sells your songs without giving you any credit. And it really hit Brian hard.” But, Love added, “the upside is that I did contribute. My cousin and I together wrote some great songs.”