Is “It Might Get Loud” the rock guitar film to end them all? There’s no doubt that U2’s fans will be intrigued to see lead guitarist The Edge finally let in some light on the three decades of mostly magic that comprise the Irish super group.

But what’s unexpected is how finely crafted the final film itself is.

Directed by Davis Guggenheim, whose last feature was the film version of Al Gore’s anxiety producing ecological slide show “An Inconvenient Truth,” you could say that Guggenheim’s latest flick is a radical departure in tone and content, being a portrait of three generations of rock guitar gods.

But although the new film shows real passion for its talented subjects, it’s not just a rehash of wearily familiar rock clichés. These guys make being in a rock group look easy, but remember that they’re once in a generation talents themselves.

Although for most of the film Jimmy Page of Led Zeppelin, The Edge and Jack White of the White Stripes talk about their love of the electric guitar quite a bit, it would be a yawn fest if the director hadn’t gotten each of them to open up, to tell their band’s stories about how they came to be, and to give a rare voice to the unheard emotional side of it all.

Guggenheim’s film succeeds at every level because he gets all three musicians to open up to each other, and in the process it turns out they have fascinating stories to tell.

The Edge has always been the reflective, quiet heart of U2, and in Guggenheim’s film he emerges as both likeable and self-deprecating, the pragmatic philosopher of the group. He’s also the signature sound of the biggest rock band in the world, but in his own words he’s just the background man who exists to make Bono look good.

Trade secrets will astound some fans. In one scene the Edge plays a few rousing bars of “Elevation,” then he turns off all the guitar effects to reveal what he’s actually playing -- a few scratchy old cords. “What I’m playing is of secondary importance to what’s coming out of the speakers,” he says. Even at his level, he’s not above a little technical trickery.

Guggenheim’s mission at every point is to get up close and personal with the three elusive men. It turns out that The Edge is both very approachable and oddly mysterious, revealing a lot and then dropping behind the curtains when he decides its time.

The film reminds us that Edge and U2 began their journey when he was still a 17-year-old schoolboy, so he’s been both an apprentice and a master of his craft all his adult life.

As each guitarist talks individually about his group, a sort of rock summit is finally arranged between the three men. This takes some doing -- being in three legendary rock bands makes scheduling a sit down chat a nightmare, but Guggenheim always gets his man.

“It Might Get Loud” surprises because it successfully attempts to get inside the heads of its subjects and discover what makes them tick. To do this Guggenheim takes them to places that have special memories.

In the case of the Edge, the director takes him to the Temple Mount High School classroom in Dublin where he and U2 first met and rehearsed when they were 16 and 17 years old (it’s a scene that’s worth the price of admission alone).

“We used to spend the first 10 minutes just clearing away all the desks before we could even begin to play,” the Edge recalls with a wry smile.

Although the three guitarists are clearly admirers of each other’s work they also hail from vastly different generations and backgrounds, and sometimes the musical tastes and sensibilities of their individual eras creates lines in the sand that they will not cross.

But in “It Might Get Loud” it’s the riff and cords that bring them together that keep winning over in the end. At the beginning of the film the three men are awkward in each other’s presence, fumbling to find common interests, and things to talk about.

But then Page finally picks up a guitar and plays the thunderous riff from Led Zeppelin’s “Whole Lotta Love,” and the film and their journey kicks in.

“It Might Get Loud” opens in New York and Los Angles on Friday, August 14.