By Phil Gallo

Beatles fans, it’s geek-out time. The newly remixed and expanded edition of The Beatles’ Sgt. Pepper’s Lonely Hearts Cub Band comes out Friday via Apple Corps/Capitol/UMe, providing a thorough examination of how John, Paul, George, Ringo and George Martin created the landmark album 50 years ago.

Gilles Martin’s stereo remix of the album alters the listening experience for anyone whose collection does not include the mono edition. Using that mono mix as a guide—it’s the only mix the Fab Four approved—he has delivered an album that pushes vocals to an imaginary center speaker, more clearly defined the instrumentation and given Ringo’s drums a more prominent and better defined spot in the mix. The bass, too, has a greater presence. (It boomed on the title track when played through this listener’s Cambridge Audio CD player and Triangle speakers powered by a Musical Fidelity amp).

The set includes the mono mix of the album plus “Penny Lane” and “Strawberry Fields Forever,” the single released in January 1967 as a placeholder between Revolver and Sgt. Pepper. Beyond that, the set includes multiple takes of tracks to demonstrate how songs came to be: There are six versions of “A Day in the Life,” for example, two of “Being for the Benefit of Mr. Kite.”

While wallowing in George’s echo-rich guitar on “Fixing a Hole,” the power of the instrumentation on “Being for the Benefit of Mr. Kite” and the density of “Good Morning Good Morning,” here, in one man’shumble opinion, are the set’s revelations.

“Lucy in the Sky With Diamonds” (new stereo remix). As the key to this exercise is creating a closer facsimile to what the Beatles actually played in the studio, “Lucy” stands out in that regard. Paul’s melodic bass lines, Ringo’s drums and George’s guitar are precisely defined, but so, too, are the instruments providing the flair—Paul’s Lowery organ, George’s tamboura, and John’s double-tracked lead vocals.

“She’s Leaving Home” (new stereo remix, Take 12). An easy one to break down for its superiority to the original: The naturalness of the strings and harp; the humanity of Macca’s vocal and dream-like state of John’s singing; and a smart separation that was stereo’s raison d’etre to start. Take 12 on a bonus disc is the gorgeous instrumental track.

“Strawberry Fields Forever” (Take 1). A bare bones take of John’s voice and guitar, a few harmony vocals and an effect here and there. It reveals the rather simple structure of the song, which gets lost underneath the finished product’s layers of effects and sound. Same can be said of “Being for the Benefit of Mr. Kite” (Take 4).

“A Day in the Life” (Takes 1, 2, 8-11). The first take is solely piano, guitar, John’s treated vocal and the clock alarm; the second adds maracas and a hint of bass. Other tracks demonstrate how hitting that final chord was not that easy a task. (Note the pinch of Gershwin being played before the recording on take 8).

“Sgt. Pepper’s Lonely Hearts Club Band” (Instrumental). The clearest indication that for all the experimentation, at their core they were still just four guys in a rock & roll band.

“Lucy in the Sky With Diamonds” (Take 1). Every track on the bonus discs reveals how well formed all of the Sgt. Pepper songs were by the time the boys entered the studio. Here, though, we catch a glimpse of a song in a transition phase. Call it “Louie, Louie in the Sky With Diamonds.”

“Within You Without You” (Take 1). Yes, the Indian instruments are indeed playing the melody. It’s not just the cellos.

“Penny Lane” (new stereo remix). When A/B’d with the stereo vinyl reissue from 2009, the remix is brighter and fuller. Gone is the isolation of vocals and trumpets in a single channel, replaced with a broader palate of sound. In addition, the bass is tightened up.

Others can debate where Sgt. Pepper fits within the Beatles’ oeuvre, but it is important to look at where The Beatles sat artistically among their peers when they were recording Sgt. Pepper between December 1966-April 1967.

They were surrounded by burgeoning psychedelic scenes and avant-garde classical music. The old guard was deciding what side they wanted to be on: The Beach Boys shelved their experimental SMiLE prior to the Sgt. Pepper sessions, choosing instead to stick with a more straight-forward approach to their new music; The Rolling Stones, ever so gently, dabbled in psychedelia on their early ’67 release Between the Buttons, an album hailed for its eclecticism.

Pink Floyd was emerging as one of Britain’s leaders in its psychedelic scene of ’66 and ’67; their first single, “Arnold Layne,” was released in April ’67 and promptly banned by the BBC.

John and Paul became exposed to acts moving rock forward at the time, taking in concerts by The Who, Jimi Hendrix Experience, Soft Machine and Pink Floyd, who were emerging as one of Britain’s leaders in psychedelia; Paul met the composer Luciano Berio.

On the singles side, where The Beatles charted with the commercial “Penny Lane” and the experimental ”Strawberry Fields Forever,” the competition was far less adventurous: Engelbert Humperdinck’s “Release Me” held onto #1 to hold “Penny Lane” at #2 in the U.K.; and in the U.S., The Stones’ “Ruby Tuesday,” The Buckinghams’ “Kind of a Drag” and Johnny Rivers’ “Baby, I Need Your Lovin’” were the Top 3 when the double-sided single entered the chart at #83.

Essays and timelines in the book that accompanies the Sgt. Pepper expanded edition explain the milieu surrounding The Beatles in ’66 and ’67. Taken collectively, it shows how the world’s biggest band took chances that would likely be inconceivable nowadays. Just as other 1967 releases—The Velvet Underground’s debut, Aretha’s singles, Hendrix, “Let’s Spend the Night Together” among them—avoid the haze of nostalgia, so, too, does this new version of a record become an improved version of a timeless classic.