The news dropped on Monday that Primus will be releasing a new album next month. Titled The Desaturating Seven, it will be the first album by the band’s classic lineup (bassist/vocalist Les Claypool, guitarist Larry LaLonde, and drummer Tim Alexander) since 1995’s Tales From The Punchbowl. The prospect is a mixed blessing for longtime fans, who may simultaneously be excited about the new music and dismayed that Primus’s already tight setlist rotation will start to feature even fewer deep cuts from the classic early ’90s phase.

The band has been mixing things up more than usual on its current tour, however, and Tuesday night’s show in the Eagles Ballroom featured some crowd-pleasing rarities, a brand new track, and a smattering of hits—if Primus can be thought of as having hits.

The opening act on this current tour is Clutch, the long-suffering stoner-rock quartet who’ve never quite reached mainstream stardom despite 26 years and 11 albums without so much as a drummer change. Singer Neil Fallon is an underrated frontman whose voice has held up amazingly well over the years; he’s one of the more overtly blues-influenced singers in the quasi-metal realm, and as evidenced by well-worn nuggets from the band’s self-titled 1995 record, his voice hasn’t lost a bit of grit or soul. He was clearly audible within a fairly well-balanced sound mix, and the sizable crowd was mostly attentive and energized.

It was a somewhat different story for Primus. The band emerged with “Too Many Puppies,” with an interlude of “Sgt. Baker” sandwiched inside, and Claypool’s vocals were washed out almost entirely in a muddy, overdriven mix. In fact, even in between songs, Claypool’s banter was often lost in competing echoes. LaLonde’s guitar didn’t fare much better; Primus’s music is more bass-focused than any other rock band you can think of, but it would never get off the ground without LaLonde’s contrasting high-flying guitar shrieks, the particulars of which were often hard to make out through the sonic haze and oppressive low end.

Claypool, who has played no other indoor venue in Milwaukee since 1997, was audibly frustrated, complaining about the sound and ventilation in the middle of the set, but this show wasn’t the first time he’d griped about The Rave, and he’ll almost certainly forget all about it the next time he’s booking a tour. The fact remains, though, that if the board engineer could wrangle decent sonics for Clutch, the acoustics of the room couldn’t be entirely to blame for how bad Primus sounded.

In terms of performance, the trio cultivated the unique dynamic between their metal and jam-band sensibilities, playing many of their heaviest songs and wedging in lengthy stretches of pre-conceived improvisational themes that often contrasted starkly with the essence of the songs they sprang from. The jams in “Moron TV” and “Candy Man” seemed to flow naturally out of the compositions, but in songs like “American Life” and “Harold Of The Rocks,” for instance, the improv portions were inserted somewhat jarringly. Still, it’s not as though fans traipse across the country following Primus, so even though the jams may have been a little forced at times, almost every song played out radically differently than its studio counterpart.

Fans were treated to the advance track from the band’s forthcoming album, “The Seven,” which sounded surprisingly fresh and yet very much in line with the group’s classic style—much more so than the mellow grooves of 2011’s Green Naugahyde, the most recent album of original Primus music. The biggest surprises stemmed from the oft-neglected Pork Soda: the band has only played “Nature Boy” a handful of times since its 2006 tour, and the rarity got the epic treatment at this show. Following this was the loopy “Welcome To This World,” which, bafflingly, has been played fewer than 10 times in Primus’s history.

Other than the never-necessary inclusion of “Wynona’s Big Brown Beaver” early in the set and the ever-present “Jerry Was A Racecar Driver,” Primus catered more to the diehards than to casual fans, and the encore of “Frizzle Fry” got a particularly enthusiastic response, suggesting that perhaps there are no longer any casual Primus fans. It remains to be seen whether the new album will be a return to form for Claypool’s songwriting or a retread of his glory days, but at least in the live setting, he continues to throw curveballs for his legions.