What seemed like a fun idea at the time was one that quickly snowballed out of control. The band that assembled for David Lee Roth’s 1986 album, Eat ‘Em and Smile -- his full-length solo debut -- was a powerful unit that featured guitarist Steve Vai, bassist Billy Sheehan and drummer Gregg Bissonette.

In November 2015, it was announced that the trio would reunite on the eve of the album's 30th anniversary to run through a few songs at Ultimate Jam Night, a weekly event hosted by Quiet Riot bassist Chuck Wright. The former bandmates said that Steel Panther’s Ralph Saenz, who had logged plenty of shows with the Van Halen tribute Atomic Punks, would be standing in for Roth. But things got a little bit crazy -- and then canceled -- once Diamond Dave himself showed up.

"When we got there, they had crammed 1,700 people in a 350-seater, and the line was literally three or four people thick all the way down [the street] and around the block," Vai tells Ultimate Classic Rock. "I’ve never seen anything like it. And then Dave got out of the car, and people just went ape s---.”

Vai recalls plans for the reunion came together casually -- "a very innocent kind of thing" involving an open-mic night. "Billy was telling me about it, and he said, ‘What if we just showed up and played a few songs?’ Like ‘Shyboy’ and ‘Yankee Rose,’ you don’t need to rehearse those,” he explains. “So I said, ‘Yeah, let’s do that.’ And then I thought maybe Dave would be interested. So I just floated it out there and he was. We didn’t do a proper rehearsal, but Dave came over to my house before we went there, and we reviewed it all and we just kind of went over it so that there was a comfort level.”

Plenty of fans were disappointed that the show was shut down, but there was hope that 2016 might bring a second shot. "We tasted a little bit of the forbidden fruit there," Vai says. "We all decided that it would be nice, why not? It was a great era. It was a great record, we were a great band. So it’s on the radar. It’s just a matter of getting everybody’s schedules to align. That’s the tough part.”

In the meantime, the guitar virtuoso is celebrating the 25th anniversary of the album that helped define his solo career, playing for the first time 1990's Passion and Warfare in its entirety. An expanded edition of the album was released in June with four bonus tracks. But Vai went beyond that with another 13 previously unreleased tracks from the era, which he released as Modern Primitive, a companion piece to the reissue.

Vai sees Modern Primitive as a collection of work that reveals what he was up to between Flex-Able, his 1984 solo debut, and the release of Passion and Warfare six years later. “The music on Flex-Able is so vastly different from Passion and Warfare that one could wonder if the same guy actually made both records,” Vai writes in the liner notes. “Modern Primitive is the missing link between these two records. It’s sort of Cro-Magnon Vai.”

The success of Flex-Able gave Vai the confidence he needed as a solo artist, he notes. “I put a band together, and I started writing material and recording basic tracks, and then I was offered an opportunity to join Alcatrazz," he recalls. "So I put everything on the shelf, and while I was with Alcatrazz, I was offered a solo record deal. At that point, I thought, ‘I’m going to start over, because I’ve got all-new musical ideas and I’m going to record a new record.’ That turned into Passion and Warfare.

"If you listen to Flex-Able and Passion and Warfare, there’s just this huge gap in the maturity and the growth. The material that I had written and partially recorded during the in-between period ... I always thought there was something in it. You get a vision for something and a lot of times you have the finished product in your head.”

Listen to Steve Vai's 'Mighty Messengers'

Vai says the music on Modern Primitive has been sitting on the “infinity shelf” for more than 30 years, and the time was just right to finally put it out. “Re-releasing an anniversary edition of Passion and Warfare with bonus tracks and remastered, was a no-brainer, he explains. "But I always like to kind of do more. So I thought, ‘What else can I do?' I thought this is the perfect opportunity to finish [the older material]."

Revisiting and finishing the tracks that appear on Modern Primitive was a task that delayed the Passion and Warfare reissue by a year. A number of the songs --which were recorded with a band called the Classified -- were never properly recorded in full. So Vai brought his old bandmates -- drummer Chris Frazier and bassist Stu Hamm -- into the studio to finish the job.

“They are a great rhythm section," Vai says. "The band had an energy and a groove. Every band has its own sort of personality in the groove. They’re better now than they were back then.”

He says it was easy to revisit that earlier era when the songs were born -- "the state of mind of the guy that wrote and recorded them." "It was one of innocence, naivete, explosion of freedom, just real enjoyment and enthusiasm and the feeling of a song,” he explains. “My feeling was, Who cares? Who really cares what Steve Vai is doing? Almost nobody except Steve Vai. That creates an opening to be wildly creative and [go] as far as you can go.”

Still, Vai notes the differences between the decades, and how he's grown as a recording artist since then. "Back then, I was struggling with technology and with my lack of certain understandings of layering tracks and how out I can really take things," he says. "But I was so happy to see how free I was back then. If you listen to that record or Flex-Able or Passion and Warfare and you look at when they came out, there was no indication why anybody would make a record like those. In that is a great freedom, because when you have no expectations, your creative impulses have an opportunity to just go wild.”

Listen to Steve Vai's 'The Audience Is Listening'

Vai was on tour with Whitesnake when Passion and Warfare landed on the Billboard album chart at No. 18 with a bullet. The album quickly went gold, and at the end of the long touring run with Whitesnake, Vai -- uncomfortable with the idea of fronting a band that was playing instrumental music and more comfortable in the sideman role -- decided to go home. Having recently expanded his family with the arrival of a child, any plans for touring behind Passion and Warfare took a backseat.

Twenty-five years later, Vai is hitting the road in support of the album. “I’m fortunate that record found a very loyal following,” he says. “When you’re inside of something and you’re working on it, you have a perspective unlike anybody else. So I always had a creative critical perspective, not a critic critical perspective.

"Through the years, my perspective on the record has changed, but when I went back to learn it and listen to it, it didn’t really hit me until we were about halfway through the [recent] European leg of the tour," he concludes. "I thought, ‘You know what? You’re really one lucky guy, Vai. You were able to make a record that bold, that long ago.”

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