Don’t freak out, but 50 years ago this weekend, the Mothers of Invention debuted in Pomona.

Frank Zappa and his cohorts weren’t at the Fox Theater or (can you imagine?) the L.A. County Fair, but at a bar named the Broadside Club.

The band was already in existence, by the way, but under a different name. Actually, a few different names.

Before this narrative grows too complicated, let’s back up and start over. There are a lot of threads to pull together.

Zappa moved with his family from the Antelope Valley to Claremont in 1959, briefly attended Chaffey College, rented a house at 315 W. G St. in Ontario and in 1964-65 owned Studio Z, a small recording studio at 8040 Archibald Ave. in Cucamonga.

Give him this, the man got around.

Various combos he was in ranged even farther: to San Bernardino’s Club Sahara, to Montclair’s Saints and Sinners (with a power trio named the Muthers) and to Pomona’s Sportsman Tavern.

It was a 1962 gig at the Sportsman, 1055 E. Holt Ave., that proved pivotal.

Ray Collins was there drinking when an R&B foursome that included Zappa set up and began to perform. Collins, a Pomona native who sang R&B and doo-wop, was delighted by the band’s selection of obscure cover songs.

Collins and Zappa struck up a musical partnership for much of 1963, performing folk song parodies at L.A. clubs, recording novelty numbers at Studio Z and co-writing a doo-wop tribute, “Memories of El Monte,” for the Penguins. Then they fell out of touch.

What proved to be the staging ground for the Mothers was across the street and a block west of the Sportsman.

The Broadside Club, 960 E. Holt Ave., was a popular bar with live music. Here’s a description courtesy of Tom Brown, a former executive with the Rhino record label whose band played there in the late 1960s:

“Netting and various sea-faring apparatus decorated the walls, while waitresses dressed like pirate floozies buzzed the tables and individuals to hawk the cheap beer being offered,” Brown wrote in his 2013 memoir, “Confessions of a Zappa Fanatic.”

In 1964, a bar band named the Soul Giants whose members included bassist Roy Estrada and drummer Jimmy Carl Black formed in Orange County.

“We got this gig at the Broadside in Pomona,” Black recalled in a 2008 video interview shortly before his death.

Collins, the key to this whole story, happened to be doing carpentry work at the Broadside. After hearing the Soul Giants’ singer, the club owner insisted he be replaced by Collins.

And soon the band had a beef with their guitarist, who was sent packing after purposely playing the wrong chords behind Collins.

“We asked Ray, ‘Do you know a guitar player?’” Black recalled. “He said, ‘Yeah, I know a guy. His name is Frank Zappa. He just got out of jail for making these porn films in Studio Z in Cucamonga.’”

This notoriety did not deter the band. Collins phoned Zappa, who auditioned and was accepted in April 1965. The Soul Giants at this point played popular dance numbers like “Louie, Louie,” “Gloria” and “In the Midnight Hour,” but this wasn’t going to get them a record contract, which was Zappa’s goal.

Zappa had barely joined up when he urged his bandmates to let him write their material. The sax player quit, saying Zappa’s music was already killing the band, but the remaining members — Black, Collins and Estrada — agreed to give it a go.

The band, which changed its name first to the Blackouts and then to Captain Glasspack and His Magic Mufflers, performed Zappa’s experimental rock music in front of baffled drinkers at such bars as the Red Flame in Pomona, the Shack in Fontana and the Tom Cat in Torrance, according to Barry Miles’ biography “Zappa.”

“Eventually we went back to the Broadside in Pomona and we called ourselves the Mothers,” Zappa said in an interview quoted by Miles. “It just happened by sheer accident to be Mother’s Day, although we weren’t aware of it at the time. When you are nearly starving to death, you don’t keep track of holidays.”

That was May 9, 1965.

The band’s future was in Hollywood, not Pomona. Zappa moved to Echo Park later that May and within a year the band — which included Black, Collins and Estrada — had a recording contract under the expanded name the Mothers of Invention.

And so Pomona was mother to the Mothers of Invention.

The Broadside and the Sportsman have been out of business for decades, although the buildings still stand, the former as an auto repair shop, the latter cleaned up and ready for lease.

Brown, the Zappa fanatic, had been amazed in 1968 to learn that his favorite musician had gotten his start at the same club at which he was then playing. He visited the former Broadside in 2009 and explained its significance to the mechanic.

It was too bad, Brown wrote, that city fathers, and mothers, haven’t recognized the building’s cultural import.

Cities as disparate as Baltimore, Berlin and the capital of Lithuania have Zappa busts, statues or streets, Brown noted, “and in Pomona, where it all happened, there is nada.”

Zappa died in 1993. Collins had become a fixture in the Claremont Village when a Zappa fan who was working on a documentary approached him in 2012 to say hello.

Tim Corvin hadn’t brought his camera for fear of scaring off the often-irascible Collins, who turned out to be in a sunny mood. When Corvin quizzed him on the precise locations of the Broadside and Sportsman, Collins said that if Corvin drove, he’d point them out.

While there wasn’t much to see, Collins noted the Broadside’s rear parking lot, where the band would hang out between sets.

“He gave me a personal tour, Ray Collins of the Mothers,” Corvin marveled to me on Thursday, recalling his excitement.

Collins died a few months later without ever agreeing to be filmed. Corvin, who is now editing his footage for a projected movie on Zappa’s Inland Valley years, returned to the former bars to film on his own.

“The Broadside is the last part of the film,” Corvin said. “That’s where Zappa’s trail ends here.”

And with that, let me wish you a happy Mother’s Day — and a happy Mothers’ Anniversary.

David Allen lacks invention Sunday, Wednesday and Friday. Contact david.allen@langnews.com or 909-483-9339, visit insidesocal.com/davidallen, like davidallencolumnist on Facebook and follow @davidallen909 on Twitter.