For 8 minutes and 2 seconds every night — sometimes longer — Led Zeppelin’s Jimmy Page sought to turn “Stairway to Heaven” into something vital and alive both for himself and the audience for whom he performed.

In a way, U2’s The Edge did follow a planned path of biological research. It’s just attuned to rhythm rather than a ribosome and in a lab cluttered not with hypotheses and Bunsen burners but effects pedals and Les Pauls. Evidenced by the unadorned riff of “Elevation,” The Edge can make more of two notes than others could with 12.

And with knuckles bloodied and streaking crimson down his fretboard, journeyman Jack White compellingly argues his claim to give each crowd at each show a unique experience — a tough drive for authenticity in a modern era of prefab concerts.

Musically speaking, Davis Guggenheim’s It Might Get Loud never does pump up the volume, chronicling a 2008 summit of these guitar gods to discuss musical maturation. Nor does the trio, as is insinuated early, come to wild and woolly belief-system blows.

Loud opens with White building a guitar from a few pieces of wood, strings and a Coke bottle — Muddy Waters meets MacGyver — and hears him proclaim when alone that technology is the big destroyer of truth and ease of use is a disease in any industry. (This from a guy who worked with the disco-ish Electric Six, mind you.) Such a verbal gauntlet might excuse The Edge for braining White with a wah-wah pedal as Page incredulously looks on.

But White’s hardened anti-technology heart softens to a jelly-like consistency, and he gets fuzzy enough around his forefathers for snippets of each other’s songs and a  jovial, acoustic end-credits run-through of The Band’s “The Weight.”

To his credit, White does come across as a purist in the most admirable form — a blues scholar and musical genealogist tracing roots from Robert Johnson to the Raconteurs and Willie Dixon to the White Stripes. If White is the anthropologist, The Edge is the scientist and Page the philosopher — the latter of whom sought to establish an ethos beyond the skiffle music and ad jingles available to him at the time.

Loud also enters dangerous documentary territory, as academically picking apart artistic processes tends to pull all passion out of the pursuit (see Jerry Seinfeld’s Comedian). However, Guggenheim evenhandedly spends time with the three sides of this story, showcasing a trio of musicians striving and struggling as much to expand what has become their signature sound as they did when it was initially inked.

Following a descending order of eminence — Page, Edge, White — Loud makes pilgrimage to hallowed ground for heralded moments. Wood beams off which John Bonham’s landmark thick backbeats bounced for “When the Levee Breaks” practically weep. The Edge barely fits in a cramped classroom where U2 got its start and reveals how 20 minutes in a store defined the 30-year sound of a band.  And White drives through his Detroit neighborhood where playing music just wasn’t cool.

After awhile, the insightfulness begins to idle and it feels like Guggenheim is goosing us for a professional — albeit no less idolized — jam-session geek-out akin to Saturday Night Live’s “Chris Farley Show” skit.

But, as with An Inconvenient Truth, Guggenheim does specialize in documentaries with accessible conclusions. You might not be The Edge, but he could just as easily have been you — working in a bank somewhere or having answered the call for “some other band.”