Editor's note: Carter Alan, music director and midday disc jockey at WZLX-FM, is the author of ``U2: Outside Is America'' (1992) and ``U2: Road to Pop'' (1997). He was the first disc jockey to play U2 on the radio in the United States.

An Irish whirlwind is returning - a group Rolling Stone magazine once called ``The band of the '80s.'' A group that didn't stop there, crashing into the '90s with one of the decade's most influential albums, ``Achtung, Baby!'', and upping the ante for stadium concert production with its ``Zoo TV'' tour.

The band stepped to the podium and mumbled thanks for armfuls of Grammies and other awards that now must overflow their mantles, walls and display cabinets. They have sold 75 million CDs, cassettes, mini-discs and even (have they been around this long?) vinyl records since 1979. And the original four-man lineup has not only remained intact since the beginning, but friendly, a rarity in rock bands.

This band is, of course, U2, and it returns to Boston next week for four long-sold-out shows at the FleetCenter.

For a group whose members are all about 40 years old, U2 has an attitude and creates music that is surprisingly fresh, yet remains marketable. The ``Elevation Tour 2001'' has been barnstorming the country since March to sold-out houses and nary a bad review. Bono, The Edge, Adam Clayton and Larry Mullen Jr. collected three more Grammys for their ``Beautiful Day'' single and more than 2 million copies of the new album, ``All That You Can't Leave Behind,'' have been purchased in the United States.

It all seems part of a similar pattern for U2 - hard and dedicated work, universal acceptance, and then rich rewards. But as recently as the band's last album, ``Pop,'' released four years ago, this wasn't the case. U2's rich legacy built up over years of carefully crafted and groundbreaking new albums as well as a reputation for dynamic and often astonishing concert spectaculars had been plowed under by a pall of consumer doubt. As both a creative and commercial force U2 bogged down in America in 1997, and it was uncertain whether the band could ever work its way out of the mire.

So what happened? U2 led its previous musical campaign in February '97 with the single ``Discotheque,'' a dance music send-up with a video that spoofed the Village People. U2, one of the world's great rock bands, had suddenly gone to the ``Y.M.C.A.'' - a moment filled with satire. But, no one seemed to get the joke. After debuting at No. 10 on the Billboard singles charts, the single sprouted an anchor and headed south, disappearing by May.

But ``Discotheque'' was just one chip off the mirrorball. The band members arrived in America in colorful designer dress at a press conference in the Manhattan K-Mart to introduce the new album and tour plans. This was dangerous territory for U2, exchanging its durable image as a creative musical force for a blatant display of kitsch, but it was all supposed to be in fun and a good album would excuse all that.

Unfortunately, ``Pop'' was not a good album by U2 standards. Filled with the electronic sounds and techno-beats that had inspired the members in the previous three or four years, it contained some terrific songs that weren't strongly realized in their recorded versions. Clouds of sonic bubble wrap got in the way as songs became slaves to form and not function. U2 had become preoccupied with the world of club music, a curious way to package and support the intense emotional and spiritual sentiments Bono had poured into his lyrics. It also proved to be a precarious path to attract record buyers - ``Pop'' barely sold a million copies in the States. U2's previous four releases combined had sold more than 25 times that.

When the massive ``Popmart Tour'' set off in April '97, the problems became more obvious. Although U2 was right on top of the dance culture, the band had skidded way past America's mainstream - which is OK unless you're trying to fill football stadiums. At the opening show in Las Vegas, technical problems marred the set's pacing and the band was clearly off its stride. There had not been enough time to rehearse with a massive new stage that weighed more than 500 tons and was dominated by a 100-foot yellow arch and a 40-foot mirrored replica of a lemon.

A special filmed by ABC-TV at the Vegas show proved to be just as big of a lemon, receiving one of the lowest ratings of any prime-time network show in history. Then, the tour failed to move the expected number of tickets once it lurched out of the desert, with U2 selling out only 10 of its first 28 concerts. Even in the cities where U2 had been strongest, it had to scale back the number of planned shows. In Philadelphia, the first show sold out, but a second was canceled because of lagging ticket sales.

After playing three Foxboro Stadium shows on its previous tour, the band settled for two New England concerts. The extravagant ``Popmart'' vehicle, polished by technical brilliance, looked pretty good by the time it got here, but its body was full of dents, engine leaking oil and its drivers shaken up as it sputtered out of America.

As work began on the new album, the members of U2 must have thought a great deal about the ``Pop'' debacle, perhaps even opening a discussion regarding damage control, since, as Edge once told me, ``To an extent, each (U2) record is a reaction to the last one.'' That ``last one'' had put U2 in a difficult place, landing the band far from the musical tolerance of its older fans and out of touch with younger alternative-minded listeners interested in the new ``faces'' of rock and rap.

But those decisions, whether deliberate or unconscious, that shaped the conception of ``All That You Can't Leave Behind'' have resulted in a critical success. One element that critics keep drawing attention to is the band's wisdom in returning to the essence of the song, a concept that powered U2's most successful album, ``The Joshua Tree.'' Up until that album, Bono says he created lyrics to ``capture the elusive message of the music'' that the band had previously recorded.

For the first time, U2 started writing complete songs and then getting into recording them - songs such as ``Bullet the Blue Sky'' which could either be played around a campfire on acoustic guitar or subjected to the howling decibel fury found on the recorded version. The group's musical substance had always carried them through, so why allow the pull of techno to divert them into a ``dry and waterless place''? This is not to say that U2 wasn't sincere when it danced under the mirrorball - it's just that somewhere within all those flashing lights, the band became imitators and not innovators. U2 can and will create whatever it wants, in whatever direction it wants, since it is a unit of members who have consistently stated they will chart their own musical destiny and stay at it as long as they aren't bored. So, whether most fans consider Pop to be a gross miscalculation or just a big mistake, for U2 it was a necessary stop on a continuing artistic ride.

``Popmart'' remains one of rock music's most expensive ventures - costing $250,000 a day to run whether U2 played a stadium or not - so somebody lost a lot of money in 1997. Like Frankenstein, the gargantuan project turned on its creator.

But having weathered that calamity, the band has wisely gotten back to the basics and is letting the music do the talking.

How long to sing this song? For more than two decades, U2 has proved that sincerity and commitment can create music that remains timeless, while perseverance has sustained it through a misstep with grace.

Although it's four years in the rearview mirror, the ``Pop'' album and ``Popmart'' tour have taught lessons that haven't been left behind. They've helped to shape U2 in the new century. The ``Elevation Tour 2001'' is stripped down in production and back to basics - no lemons, musical or otherwise - and for this band at this time, that can only be a good thing.