Metal Alliance Tour a mind-grinding look back at thrash 

With thrash metal, the past is never far from the present. This is true with the various iconic bands still peddling their rapid-fire riffs and torrential rhythms and with younger groups which closely adhere to the examples their forebears set. It's a genre that's formulaic by design, one obsessed with technical precision within its time-tested patterns. Each outfit strives to impress through its own distinct chops and personality, but the wiggle room is minimal.

This spring's Metal Alliance Tour is a perfect opportunity to become better acquainted with the genre's history. Anchored by Exodus and Anthrax, two fundamental pillars from the genre's early days, the bill — which hits Tremont Music Hall on April 13 — is highlighted by heavy-hitting royalty only moderately diminished from their heydays. Given that those glory days are more than two decades in the rearview, anything beyond competence would feel like a feat.

Emerging in 1980, Exodus was an early thrash pioneer, lording over the fledgling style from its Bay Area home base with slashing riffs and snarls paired to its punishing rhythms. The band's prominence was short-lived as Slayer, Megadeth and Metallica — who ended up incorporating Exodus guitarist Kirk Hammett — arrived to exceed the popularity of the trailblazing outfit. Along with those three mainstays, Anthrax rounds out what is typically referred to as thrash metal's "Big Four." Catalyzed by Dan Spitz and Scott Ian's intricately churning guitars, Anthrax's legendary stretch from 1985 to 1990 was a blur of viciously controlled momentum enlivened by a sense of fun which set them apart from the other, more serious members of the Four.

For Ryan Waste, guitarist for Anthrax and Exodus' Richmond-based tourmate Municipal Waste, the groups were key influences.

"I think it's an unconscious effort for us," speaking of his thrash forbears' impact. Though the outfit's style comes naturally and is inflected by other punk and metal strains, he sees Municipal Waste as a torchbearer for such old-school heavy fare. "If it keeps getting people into older bands that we're into, our job is done. We owe them as fans, just growing up with that kind of music. That's why this tour is so important to us, because I might not be playing guitar if I didn't listen to Exodus and Anthrax when I was a kid. It's all come around full circle for me, man, and I can just check it off my life. We're doing it."

Anthrax and Exodus offer insight into thrash's essential foundations, but Municipal Waste paints a clearer picture of the genre's place within the current heavy music landscape. Springing to life in 2000, the band falls in with a long line of crossover bands which blend thrash with hardcore elements. Listen to early albums from Suicidal Tendencies and Raleigh's Corrosion of Conformity, and you'll find that most of Municipal Waste's stylistic markers were established decades before the group began dominating stages and gobbling up rave reviews from critics who recognized its music as a vital reinterpretation and not simple revivalism.

Waste rightly notes that such bandwagon antics — whether they come by way of an old band reforming for a cash grab or a new group seeking to force themselves on a marketable style — harm the overall crossover and thrash image in the eyes of those less familiar with the music.

"You can see by the test of time who's in it for real," he says. "If it's just some phase where someone goes, 'Oh, this is popular. I'm going to try doing a thrash band now,' then it gets oversaturated. [That's] kind of what happened in the late '80s. There were so many bands playing that style. I'm not saying people got sick of it. Times change, and the true metal warriors are here to stay. When I first started the band, I was just playing the kind of music I was listening to, and I still listen to it. As far as older bands getting back together, I think it's great as a fan, being in my 30s and not catching some of these shows when they were happening back in the day. But if they're back just to cash in — if money gets involved with anything, then somebody's going to get upset, and it's probably not going to last."

Even when it's genuine, thrash — especially when it's spattered with the fun-loving gore preferred by Municipal Waste — is somewhat at odds with much of the metal catching attention these days. In America, black metal has gone transcendental with bands like Liturgy and Wolves in the Throne Room espousing complex philosophy over windswept riffs that are more immersive than violent. Where brutality reigns, it often does so with nihilistic menace; see the thunderous bludgeoning of Portland's The Body for a particularly intense example. None of these bands enjoys the popularity thrash titans claimed in the '80s, but the interest surrounding them does throw the genre's future into doubt.

Waste, for one, isn't worried, and it shows on The Fatal Feast, the band's potent 2012 platter. Playing as tight as it ever has, the outfit surges with riffs which are both rapid and concussive, backed by rhythms so swift they flirt with blast beats. Tony Foresta is equally unflinching with his vocals. He growls purposefully about alien abductions and eating brains, having so much fun with B-horror tropes that he makes the common punk tactic seem surprisingly fresh.

"To me, heavy metal and thrash is timeless," Waste says. "It stands the test of time. It could be coming out at any time, and it doesn't seem dated to me. I prefer the classic stuff myself, and I don't think you can even put a date on it. There's just so much honesty to it and rawness that it doesn't matter if it's new or old if you're doing it with your heart in it. You can't stray away from that formula and try to make it appeal to everybody. It's always going to appeal to people who are truly into it and are into it for life. I'm in it for life."