A cool front is moving into the Joint, and it is Def Leppard

Weeks before Def Leppard opened its string of shows at the Joint at the Hard Rock Hotel, frontman Joe Elliott talked of Rat Pack and rock ’n’ roll cool.

Brandishing a microphone and a thermometer, Elliott says those degrees of cool are not always the same temperature.

“Maybe it’s is an old thing, you know, the cool like Dino, Sammy Davis Jr. and Frank had, when they were doing it, it was cool, especially at the time,” Elliott said, picking through the names of Dean Martin and Frank Sinatra along with Sammy Davis Jr. “But we’re actually very cool, too. It has become a very rock-and-roll cool to play Las Vegas.”

Elliott held up Celine Dion and Elton John at the Colosseum to convey the type of cool Def Leppard is toting to the stage at the Hard Rock.

“One can argue about Celine Dion, if she is cool,” he said. “But you can’t argue that Elton Elton’s pretty cool, you know? It’s become, in this day and age, that if Roger Waters announced he was going to do ‘The Wall’ in Vegas, I don’t think anybody would blink.”

Perhaps. More likely, scores of fans would blink and ask, “Where can we see Roger Waters do ‘The Wall,’ and how much are tickets?”

Since that phone chat, Def Leppard has taken stage in an inarguably cool haven, playing a series of shows dubbed “Viva Hysteria” and playing the “Hysteria” album end-to-end. The band’s stay in Las Vegas ends April 13.

This is a befitting hall for Def Leppard, friendly and welcoming to quasi-nostalgic rock acts of the 1980s. The Joint is where veteran rockers strut best. It has served as an ideal playground for Motley Crue and the reconfigured Guns N’ Roses, both of whom used the arena-size stage to put on dazzling audio/video productions (the Crue’s use of little people impersonating the band amid this fury was especially inspired). Santana played the Joint for two years, with the vast LED screens exploding with psychedelia and footage of the band’s mescaline-fueled appearance at Woodstock.

Not to endorse the use of mescaline, but that was terribly cool.

Consequently, Def Leppard had a high standard to meet, cool-wise and otherwise. The opening set of the 2 ½-hour show is curiously stripped down, with the band jokingly referring to itself as its own opening act. The only stage effects were pulsating lights and a giant Union Jack stretched across the back of the stage. Elliott was about unrecognizable, his face hidden behind oversized shades. He wore a brown top hat seemingly made of leather, jeans and a beige jacket. His T-shirt was a depiction of John Lennon’s “Working Class Hero” poster.

And for 40 minutes, it was just a rock show. A hard-driving rock show, to be sure. The band reached back, long and deep, for such long-forgotten cuts as “When Love and Hate Collide,” “Stagefright” and “Wasted,” songs so indistinguishable and murky you need to research them to make sure the band wasn’t covering someone else’s catalogue.

After the 15-minute intermission, during which old clips of the band dating to the 1980s were played for the audience (Elliott was one who made the frizzy mullet a cool look), the band’s generous investment in staging was finally unleashed. This was a very cool, rockin’, very Vegas spectacle.

Elliott swapped the hat and fly shades for black leather and denim. Built behind the stage were tiers for the band members to clamber upon, and the LED screens were used abundantly and impressively. The multi-leveled stage beamed dozens of TV screens, crisscrossing strobes and spotlights and the cursive lyrics, “Love bleeds just for show, love is, love begs, love pleads.”

Whether that is true is beside the point. In 10-foot-high lettering at the back of the stage at the Joint, it looks very cool. It likely played well to the video team shooting the show for an upcoming concert/documentary DVD.

Because the “Hysteria” album is recited purely, one of the most infectious sing-along songs ever, “Pour Some Sugar On Me,” lands about in the middle of the set. This is a classic encore song, and there is a song played as an encore (leave it to you to guess, but it’s not from “Hysteria).” That’s a very cool move, to toss out a show-closing anthem 30 minutes before the show actually closes.

Beyond the heavy production and super-solid set list was the swagger of the musicians themselves. The guys in Def Leppard really enjoy being rock stars, and like the speed limit on Nevada highways, the age barrier for rock and rollers keeps edging toward 80.

These guys carrier their maturity very well, knowing that if you must saunter around the stage shirtless, you’d better find the nearest gym. Guitarist Phil Collen, who looks like he’s about to compete in an Olympic gymnastics event, realizes this. As he walked past Elliott after performing the ripping solo in “Rocket,” Collen enthusiastically high-fived the singer as if he’d just scored a “10” on the pommel horse.

Very cool. Give it up for Def Leppard, temporary Lords of the Joint and rockers for the ages. Some of us weren’t around to enjoy the Rat Pack in its heyday, but we’ll hang with these guys any time.

Follow John Katsilometes on Twitter at Twitter.com/JohnnyKats. Also, follow “Kats With the Dish” at Twitter.com/KatsWiththeDish.